JP6612964B1 - Optical fiber manufacturing method and optical fiber manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber manufacturing method and an optical fiber manufacturing apparatus capable of suppressing a decrease in mechanical strength of an optical fiber while suppressing a deviation in thickness of a resin coating layer. A method of manufacturing an optical fiber 1 includes inserting a bare optical fiber 1N from above the first housing chamber 44 into a first housing chamber 44 in which an upper portion is opened and an inner resin 61 is stored, and a first die port 55H. A first resin coating step P4 that is extracted from the second die chamber 55H in which the inner resin 61 is filled with a predetermined pressure; Resin application process P5, and third resin application process P6 in which the optical fiber bare wire 1N is inserted into the third housing chamber 46 filled with the outer resin 62 at a predetermined pressure from the second die port 56H and extracted from the third die port 57H. And comprising. [Selection] Figure 3

Description

  The present invention relates to an optical fiber manufacturing method and an optical fiber manufacturing apparatus, and more particularly to an optical fiber manufacturing method having a resin coating layer and an optical fiber manufacturing apparatus.

  Conventionally, an optical fiber in which the outer periphery of a core is surrounded by a clad and the outer peripheral surface of the clad is covered with a resin coating layer composed of a plurality of layers is known. An optical fiber manufacturing method is disclosed.

  In the following Patent Document 1, an inner resin is formed by using a die body having a first storage chamber having an upper opening and a lower die opening, and a second storage chamber having an insertion opening and a lower die opening. A method of manufacturing an optical fiber having a resin coating layer composed of a layer and an outer resin layer is disclosed. In such an optical fiber manufacturing method using a die body, an inner resin serving as an inner resin layer is stored in the first housing chamber, and an outer resin serving as an outer resin layer is stored in the second housing chamber at a predetermined pressure. Filled. In this optical fiber manufacturing method, an optical fiber bare wire having no resin coating layer is inserted into the first housing chamber from above and extracted from the die port, and an uncured inner resin is applied to the outer peripheral surface of the optical fiber bare wire. To do. Further, the outer peripheral surface of the bare optical fiber coated with the uncured inner resin is inserted into the second storage chamber through the insertion port and extracted from the die port through the uncured inner resin coated with the uncured inner resin. An uncured outer resin is applied to the substrate. The uncured inner resin and outer resin applied in this way are cured to form the inner resin layer and the outer resin layer.

  Further, in Patent Document 1 below, the upper portion of the first storage chamber is closed and an insertion port for inserting a bare optical fiber is provided above the first storage chamber, and the inner side serving as an inner resin layer. An optical fiber manufacturing method using a die body that is different from the die body in that the resin is filled in the first storage chamber at a predetermined pressure is disclosed.

International Publication No. 99/32415

  When using the die main body with the upper side of the first storage chamber opened as in one manufacturing method described in Patent Document 1, the uncured inner resin is stored in the first storage chamber with the upper side opened. Therefore, convection occurs in the inner resin with the movement of the bare optical fiber passing through the first housing chamber, and a meniscus that is recessed in a concave shape around the bare optical fiber is formed on the liquid surface of the inner resin that contacts the gas. This convection may become unstable due to the viscosity of the inner resin, the extraction speed of the bare optical fiber, or the like. If the convection becomes unstable, the pressure of the uncured inner resin poured out from the die port together with the bare optical fiber will fluctuate, resulting in a deviation in the thickness of the inner resin to be applied and a deviation in the thickness of the inner resin layer. May occur, and as a result, the thickness of the resin coating layer may be biased. For example, when the thickness of the inner resin layer is reduced in an optical fiber having a double clad structure in which the inner resin layer is an outer cladding, excitation light may leak from a portion where the thickness of the inner resin layer is reduced. For this reason, there is a desire to suppress the occurrence of unevenness in the thickness of the resin coating layer.

  On the other hand, when using a die body in which an insertion port is formed above the first storage chamber as in the other manufacturing method described in Patent Document 1, uncured inner resin is applied to the first storage chamber at a predetermined pressure. Filled with. For this reason, it is suppressed that the above meniscus is formed in the inner resin, and the flow of the inner resin is suppressed from becoming unstable. Therefore, in such a manufacturing method, fluctuations in the pressure of the uncured inner resin poured out from the die port together with the bare optical fiber are suppressed, and deviations in the thickness of the inner resin layer are suppressed. Thus, it is possible to suppress the occurrence of unevenness in the thickness of the resin coating layer.

  By the way, in the optical fiber manufacturing method, when forming the bare optical fiber in which the optical fiber preform is drawn and the outer periphery of the core is surrounded by the clad, the optical fiber preform is rotated to rotate the bare optical fiber. May be permanently twisted. For this reason, in the manufacturing method of the optical fiber of the said patent document 1, it is possible to use the optical fiber bare wire formed by drawing, for example, rotating the optical fiber preform. In this case, the optical fiber bare wire may be shaken in the direction perpendicular to the longitudinal direction due to the centrifugal force generated by the rotation of the optical fiber preform. As described above, when the first storage chamber is filled with uncured inner resin at a predetermined pressure, the outer peripheral surface of the bare optical fiber comes into contact with the edge of the insertion port of the first storage chamber in the die body. There is a possibility that the outer peripheral surface of the bare wire is damaged and the mechanical strength of the optical fiber is lowered.

  Accordingly, the present invention provides an optical fiber manufacturing method and an optical fiber manufacturing apparatus capable of suppressing the mechanical strength of the optical fiber from being lowered while suppressing the occurrence of bias in the thickness of the resin coating layer. With the goal.

  In order to achieve the above object, an optical fiber manufacturing method of the present invention includes a core, a clad surrounding the outer peripheral surface of the core, an inner resin layer covering the outer peripheral surface of the clad, and an outer peripheral surface of the inner resin layer. An optical fiber having a resin coating layer including an outer resin layer to be coated, the inner resin serving as a part of the inner resin layer being opened while having an upper opening and a lower first die port. An optical fiber bare wire having the core and the clad is inserted into the first containing chamber from above the first containing chamber, and is extracted from the first die port, and the inner resin is placed on the outer peripheral surface of the bare optical fiber. A first resin application step of applying the inner resin to be a part of the layer; and the inner side to have the first insertion port on the upper side and the second die port on the lower side and to be another part of the inner resin layer. Resin fills at the specified pressure The optical fiber bare wire coated with the inner resin, which is a part of the inner resin layer, is inserted into the second storage chamber and is extracted from the second die port, and the inner resin is removed. A second resin application step of applying the inner resin as another part of the inner resin layer to the outer peripheral surface of the bare optical fiber to which the inner resin as a part of the layer is applied; The inner resin serving as another part of the inner resin layer in a third storage chamber having an insertion port and a third die port below and filled with an outer resin serving as the outer resin layer at a predetermined pressure The optical fiber bare wire coated with the inner resin, which is inserted into the second insertion port and pulled out from the third die port, and becomes the other part of the inner resin layer. 3rd resin application which apply | coats the said outer side resin to the outer peripheral surface of Characterized in that it comprises a degree, the.

  In this optical fiber manufacturing method, the uncured inner resin that becomes the inner resin layer in the first resin application step and the second resin application step is applied to the outer peripheral surface of the bare optical fiber, and the third resin application step An uncured outer resin serving as an outer resin layer is coated on the outer peripheral surface of the bare optical fiber coated with the cured inner resin. The uncured inner resin and outer resin thus applied are cured to form an inner resin layer and an outer resin layer. In this optical fiber manufacturing method, the bare optical fiber is passed through the first storage chamber, the second storage chamber, and the third storage chamber in this order, and the upper portion of the first storage chamber is open. For this reason, compared with the case where the first storage chamber is filled with the uncured inner resin as in the manufacturing method described in Patent Document 1, the bare optical fiber is shaken in the direction perpendicular to the longitudinal direction. Even if it occurs, it is possible to prevent the outer peripheral surface of the bare optical fiber from coming into contact with the member in which the first housing chamber is formed, and to damage the outer peripheral surface of the bare optical fiber. It can suppress that it falls. Further, in this optical fiber manufacturing method, in the second resin coating step, the second housing chamber filled with a predetermined pressure with the inner resin, which is another part of the inner resin layer, becomes a part of the inner resin layer. Pass the bare optical fiber coated with the inner resin. And inner resin used as the other part of an inner side resin layer is apply | coated to the outer peripheral surface of the bare optical fiber with which inner side resin used as a part of inner side resin layer was apply | coated. Since the second storage chamber is filled with the inner resin at a predetermined pressure, it is in an uncured state that is poured out from the second die port together with the bare optical fiber coated with the inner resin that becomes a part of the inner resin layer. Fluctuations in the pressure of the inner resin are suppressed. Therefore, even if a deviation occurs in the thickness of the inner resin applied to the outer peripheral surface of the bare optical fiber in the first resin application step, the inner resin is applied so as to level the deviation in the second resin application step. It is possible to suppress the occurrence of unevenness in the thickness of the inner resin layer. Further, in the third resin coating step, the outer circumference of the bare optical fiber coated with the inner resin by passing the bare optical fiber coated with the inner resin through the third housing chamber filled with the outer resin at a predetermined pressure. Apply the outer resin to the surface. For this reason, it is suppressed that the thickness of the outer side resin layer is uneven. Thus, in this optical fiber manufacturing method, it is possible to suppress the occurrence of unevenness in the thickness of the inner resin layer and the outer resin layer in the resin coating layer, and it is possible to suppress the occurrence of unevenness in the thickness of the resin coating layer.

  In addition, a cylindrical guide member that surrounds the bare optical fiber is disposed at least apart from the outer peripheral surface of the bare optical fiber in the inner resin accommodated in the first accommodating chamber, and the guide member is The inner resin may be allowed to flow into the inner region of the guide member.

  By doing in this way, the convection which arises in the inner side resin stored by the 1st storage chamber can be formed in the area | region of the optical fiber bare wire side rather than a guide member. For this reason, compared with the case where a guide member is not arrange | positioned, the area | region in which this convection arises in this inner side resin can be narrowed, and the meniscus recessed in a concave shape can be made small, and convection can be stabilized. For this reason, it can suppress that the thickness of the inner side resin applied to the outer peripheral surface of the bare optical fiber in the first resin application step is uneven.

  The guide member may be disposed before storing the inner resin in the first storage chamber.

  By doing in this way, a guide member can be arrange | positioned easily compared with the case where a guide member is arrange | positioned after storing inner side resin in a 1st storage chamber.

  In addition, when a guide member is disposed in the first storage chamber, a communication portion that communicates the outer region and the inner region of the guide member in the inner resin is formed on the side surface of the guide member. It is also good.

  By doing in this way, compared with the case where the communication part is not formed on the side surface of the guide member, it is possible to easily flow the inner resin located in the outer region of the guide member into the inner region of the guide member, Convection in the inner resin stored in the first storage chamber can be further stabilized. For this reason, it is possible to further suppress the occurrence of bias in the thickness of the inner resin applied to the outer peripheral surface of the bare optical fiber in the first resin application step.

  The resin constituting the inner resin layer may be a resin having a refractive index lower than that of the clad.

  By doing so, it is possible to manufacture an optical fiber having a double clad structure in which the clad of the bare optical fiber is the inner clad and the inner resin layer is the outer clad.

  The optical fiber manufacturing method may further include a drawing step of forming the bare optical fiber by drawing the optical fiber preform while rotating the optical fiber preform around the central axis of the optical fiber preform. good.

  By doing in this way, permanent twist can be given to an optical fiber bare wire. For example, in an amplification optical fiber having a double-clad structure in which a bare optical fiber is an inner clad and an inner resin layer is an outer clad, a permanent twist is imparted to the bare optical fiber. It is possible to make the light propagating through the inner cladding easier to enter the core while suppressing the light more. For this reason, the absorption efficiency of the excitation light in the amplification optical fiber having the double clad structure can be increased. When the optical fiber preform is drawn while being rotated around the central axis of the optical fiber preform, the bare optical fiber tends to be easily shaken in a direction perpendicular to the longitudinal direction. However, according to the above-described optical fiber manufacturing method, it is possible to suppress a decrease in the mechanical strength of the optical fiber even when the bare optical fiber is shaken in a direction perpendicular to the longitudinal direction. For this reason, this optical fiber manufacturing method is particularly useful when an optical fiber bare wire is formed by drawing the optical fiber preform while rotating it around the central axis of the optical fiber preform. .

  In addition, the pressure of the outer resin filled in the third storage chamber may be smaller than the pressure of the inner resin filled in the second storage chamber.

  The first die port of the first storage chamber may also serve as the first insertion port of the second storage chamber.

  In this manufacturing method, the optical fiber bare wire passes through the first die port, is coated with the inner resin that becomes a part of the inner resin layer, and is inserted into the second storage chamber. Therefore, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, compared to the case where the first die port of the first storage chamber does not serve as the first insertion port of the second storage chamber, It is possible to prevent the inner resin applied to the bare optical fiber from coming into contact with the edge of the first insertion port of the second storage chamber. Therefore, compared to the case where the first die port does not serve as the first insertion port of the second storage chamber, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, It is possible to further suppress the occurrence of unevenness in the thickness of the applied inner resin.

  The second die port of the second storage chamber may also serve as the second insertion port of the third storage chamber.

  By doing in this way, the inner side resin which becomes another part of the inner side resin layer is applied to the bare optical fiber by passing through the second die port, and is inserted into the third storage chamber. For this reason, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, compared to the case where the second die port of the second storage chamber also serves as the second insertion port of the third storage chamber, It is possible to prevent the inner resin applied to the bare optical fiber from coming into contact with the edge of the second insertion port of the third storage chamber. Therefore, compared with the case where the second die port does not serve as the second insertion port of the third storage chamber, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, It is possible to further suppress the occurrence of unevenness in the thickness of the applied inner resin.

  Further, in the above optical fiber manufacturing method, the outer resin is applied to the fourth storage chamber having the third insertion port on the upper side and the fourth die port on the lower side and filled with a predetermined resin at a predetermined pressure. The optical fiber bare wire thus inserted is inserted through the third insertion port and extracted from the fourth die port, and the predetermined resin is applied to the outer peripheral surface of the optical fiber bare wire coated with the outer resin. It is good also as providing the resin application | coating process further.

  By doing in this way, the optical fiber which has the resin coating layer containing three resin layers can be manufactured.

  The optical fiber manufacturing apparatus of the present invention includes a core, a clad surrounding the outer peripheral surface of the core, an inner resin layer covering the outer peripheral surface of the clad, and an outer resin layer covering the outer peripheral surface of the inner resin layer. An optical fiber manufacturing apparatus comprising: a resin coating layer including: a first housing chamber in which an upper resin is opened and has a first die opening at a lower portion, and an inner resin serving as a part of the inner resin layer is stored therein. A second storage chamber having a first insertion port on the upper side and a second die port on the lower side and filled with the inner resin as another part of the inner resin layer at a predetermined pressure; A die body having a second insertion port, a third die port at the bottom, and a third storage chamber filled with an outer resin serving as the outer resin layer at a predetermined pressure; Is an optical fiber having the core and the cladding. A bare wire passes through the first die port from above, and the bare optical fiber that has passed through the first storage chamber passes from the first insertion port to the second die. The optical fiber bare wire that has passed through the second storage chamber is passed through the third storage chamber so as to pass from the second insertion port to the third die port. Features.

  In this optical fiber manufacturing apparatus, the bare optical fiber is passed through the first storage chamber, the second storage chamber, and the third storage chamber in this order, and the upper portion of the first storage chamber is open. For this reason, as described above, even if the optical fiber bare wire shakes in the direction perpendicular to the longitudinal direction, the outer peripheral surface of the bare optical fiber comes into contact with the die body and comes to the outer peripheral surface of the bare optical fiber. Scratches can be suppressed, and a decrease in mechanical strength of the optical fiber can be suppressed. Further, in this optical fiber manufacturing apparatus, the optical fiber bare wire coated with the inner resin that becomes a part of the inner resin layer is filled with the inner resin that becomes the other part of the inner resin layer at a predetermined pressure. 2 Pass through the containment chamber. For this reason, as described above, even if a deviation occurs in the thickness of the inner resin that becomes a part of the inner resin layer applied to the outer peripheral surface of the bare optical fiber, the inner resin layer is made to level the deviation. The other part of the inner resin can be applied, and the occurrence of unevenness in the thickness of the inner resin layer can be suppressed. Further, in this optical fiber manufacturing apparatus, since the bare optical fiber coated with the inner resin passes through the third housing chamber filled with the outer resin at a predetermined pressure, the thickness of the outer resin layer is as described above. It is suppressed that the bias is generated. In this way, the optical fiber manufacturing apparatus can suppress a decrease in the mechanical strength of the optical fiber while suppressing the occurrence of unevenness in the thickness of the resin coating layer.

  The optical fiber manufacturing apparatus further includes a cylindrical guide member that surrounds the bare optical fiber at a distance from the outer peripheral surface of the bare optical fiber in at least the inner resin stored in the first storage chamber. The guide member may be configured to allow the inner resin to flow into a region inside the guide member.

  In the optical fiber manufacturing apparatus, as described above, the convection in the inner resin stored in the first storage chamber is stabilized by the guide member, and the thickness of the inner resin applied to the outer peripheral surface of the bare optical fiber is biased. This can be suppressed.

  When the optical fiber manufacturing apparatus includes a guide member, a side surface of the guide member may be formed with a communication portion that communicates the outer region and the inner region of the guide member in the inner resin. .

  By doing in this way, compared with the case where the communication part is not formed on the side surface of the guide member, it is possible to easily flow the inner resin located in the outer region of the guide member into the inner region of the guide member, Convection in the inner resin stored in the first storage chamber can be further stabilized. For this reason, it can suppress more that the thickness arises in the inner side resin applied to the outer peripheral surface of the bare optical fiber.

  The first die port of the first storage chamber may also serve as the first insertion port of the second storage chamber.

  With such a configuration, the die body can be miniaturized. In this optical fiber manufacturing apparatus, as described above, the bare optical fiber is applied to the inner resin layer as a part of the inner resin layer by passing through the first die port and is inserted into the second storage chamber. The Therefore, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, compared to the case where the first die port of the first storage chamber does not serve as the first insertion port of the second storage chamber, It is possible to prevent the inner resin applied to the bare optical fiber from coming into contact with the edge of the first insertion port of the second storage chamber. Therefore, compared to the case where the first die port does not serve as the first insertion port of the second storage chamber, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, It is possible to further suppress the occurrence of unevenness in the thickness of the applied inner resin.

  The second die port of the second storage chamber may also serve as the second insertion port of the third storage chamber.

  With such a configuration, the die body can be miniaturized. Further, in this optical fiber manufacturing apparatus, as described above, the bare optical fiber is coated with the inner resin that becomes another part of the inner resin layer by passing through the second die port, and in the third storage chamber. Inserted. Therefore, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, the second die port of the second storage chamber is compared with the case where the second insertion port of the third storage chamber does not serve as well. It is possible to prevent the inner resin applied to the bare optical fiber from coming into contact with the edge of the second insertion port of the third storage chamber. Therefore, compared with the case where the second die port does not serve as the second insertion port of the third storage chamber, even if the optical fiber bare wire is shaken in the direction perpendicular to the longitudinal direction, It is possible to further suppress the occurrence of unevenness in the thickness of the applied inner resin.

  As described above, according to the present invention, an optical fiber manufacturing method and an optical fiber manufacturing capable of suppressing the mechanical strength of the optical fiber from being lowered while suppressing the occurrence of unevenness in the thickness of the resin coating layer. An apparatus is provided.

It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the optical fiber which concerns on embodiment of this invention. It is a figure showing roughly the manufacturing device of the optical fiber concerning the embodiment of the present invention. It is a figure which shows schematically the application part shown by FIG. FIG. 4 is a perspective view schematically showing a guide member shown in FIG. 3. It is a flowchart which shows the manufacturing method of the optical fiber which concerns on embodiment of this invention. It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the preform | base_material for optical fibers prepared at a preparation process. It is a figure which shows the guide member which concerns on a modification. It is a figure which shows the application part used in Example 1 similarly to FIG. It is a figure which shows the optical fiber manufactured in Example 1 similarly to FIG. It is a figure which shows the application part used by the comparative example 1 similarly to FIG. It is a figure which shows the application part used by the comparative example 2 similarly to FIG. It is a figure which shows a part of the mode of the bending test of an optical fiber.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an optical fiber manufacturing method and an optical fiber manufacturing apparatus according to the present invention will be described in detail with reference to the drawings. The embodiments exemplified below are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the spirit of the present invention. In the drawings referred to below, the dimensions of the respective members may be changed and shown for easy understanding.

  FIG. 1 is a view showing a cross section perpendicular to the longitudinal direction of an optical fiber according to an embodiment of the present invention. As shown in FIG. 1, the optical fiber 1 mainly includes an optical fiber bare wire 1N and a resin coating layer 12 that includes at least two resin layers and covers the outer peripheral surface of the optical fiber bare wire 1N. The bare optical fiber 1 </ b> N of the present embodiment includes a core 10 and a clad 11 that surrounds the outer peripheral surface of the core 10. The resin coating layer 12 of this embodiment includes an inner resin layer 13 that covers the outer peripheral surface of the clad 11, an outer resin layer 14 that covers the outer peripheral surface of the inner resin layer 13, and a resin that covers the outer peripheral surface of the outer resin layer 14. It consists of a protective layer 15. In the present embodiment, the optical fiber 1 is an amplification optical fiber having a double clad structure in which the clad 11 is an inner clad and the inner resin layer 13 is an outer clad. Therefore, in this embodiment, it can be understood that the clad 11 is an inner clad and the inner resin layer 13 is an outer clad. For this reason, the refractive index of the clad 11 as the inner clad is lower than the refractive index of the core 10, and the refractive index of the inner resin layer 13 as the outer clad is lower than the refractive index of the clad 11 as the inner clad. The core 10 is disposed at the center of the clad 11.

  As a material constituting the core 10 of the present embodiment, silica glass containing an active element such as ytterbium (Yb) that is excited by excitation light can be cited. Examples of the active element include rare earth elements other than ytterbium. Examples of the rare earth element include thulium (Tm), cerium (Ce), neodymium (Nd), europium (Eu), erbium (Er), and the like. Is mentioned. Furthermore, bismuth (Bi) etc. can be mentioned as an active element other than a rare earth element. This active element generally has a property as a dopant that increases the refractive index of the core 10. In addition to the active element, the material constituting the core 10 includes germanium (Ge), phosphorus (P), aluminum (Al), titanium (Ti), chlorine (Cl), boron (for adjusting the refractive index) B), a dopant such as fluorine (F) may be added. Furthermore, an element that lowers the refractive index, such as fluorine (F) or boron (B), may be added to the material constituting the core 10 in order to adjust the refractive index.

  In the present embodiment, the outer periphery of the clad 11 is generally a regular heptagon in a cross section perpendicular to the longitudinal direction. That is, the outer shape of the bare optical fiber 1N in the cross section perpendicular to the longitudinal direction is approximately a regular heptagon. Thus, in this embodiment, since the outer shape of the clad 11 is non-circular, the light propagating through the clad 11 changes the reflection angle on the outer peripheral surface of the clad 11 that is the outer peripheral surface of the bare optical fiber 1N. The reflection can be repeated, and the light propagating through the cladding 11 can be easily incident on the core 10. For this reason, skew light can be suppressed compared with the case where the outer shape of the clad 11 is circular. In the present embodiment, the bare optical fiber 1 </ b> N is given a twist about the central axis of the core 10. For this reason, the outer peripheral surface of the non-circular clad 11 is twisted in the longitudinal direction, and the light propagating through the clad 11 can be easily incident on the core 10 while suppressing the skew light. For this reason, the absorption efficiency of the excitation light in the optical fiber 1 which is an optical fiber for amplification having a double clad structure can be increased.

  Examples of the material constituting the clad 11 as the inner clad include pure silica glass to which no dopant is added. Note that an element such as fluorine (F) that lowers the refractive index may be added to the material constituting the clad 11.

  The inner resin layer 13 as the outer cladding is made of a resin, and examples of the resin include an ultraviolet curable resin and a thermosetting resin.

  The outer resin layer 14 is made of a resin different from the resin constituting the inner resin layer 13, and examples of the resin include an ultraviolet curable resin and a thermosetting resin.

  The resin protective layer 15 is made of a resin different from the resin constituting the outer resin layer 14, and examples of the resin include an ultraviolet curable resin and a thermosetting resin.

  The resin constituting the outer resin layer 14 and the resin protective layer 15 is preferably an ultraviolet curable resin when the inner resin layer 13 is an ultraviolet curable resin, and the inner resin layer 13 is a thermosetting resin. In this case, it is preferable to use a thermosetting resin. By doing in this way, the resin used as the inner side resin layer 13, the resin used as the outer side resin layer 14, and the resin used as the resin protective layer 15 can be hardened at a time, and the productivity of the optical fiber 1 can be improved. .

  Next, an optical fiber manufacturing apparatus according to an embodiment of the present invention will be described.

  FIG. 2 is a diagram schematically showing an optical fiber manufacturing apparatus according to the present embodiment. The optical fiber 1 manufacturing apparatus 100 shown in FIG. 2 mainly includes a base material feeding device 20, a heating furnace 25, a cooling device 30, a coating layer forming device 40, a turn pulley 80, a take-up device 81, and a winding device 82. Prepare. The optical fiber 1 is manufactured by the optical fiber manufacturing apparatus 100.

  The preform feeding device 20 is a device that feeds the optical fiber preform 1P into the heating furnace 25 from the lower end side at a predetermined speed. In the present embodiment, the preform feeding device 20 is attached to the upper end portion of the optical fiber preform 1P that becomes the bare optical fiber 1N, and the optical fiber preform 1P is disposed around the central axis of the optical fiber preform 1P. It is set as the structure which can be sent in in the heating furnace 25, rotating at predetermined speed.

  The heating furnace 25 is a furnace that heats the optical fiber preform 1P fed by the preform delivery apparatus 20. In the present embodiment, the heating furnace 25 includes a furnace core tube 26, a heating element 27, and a heat insulating material 28 as main components, and the optical fiber preform 1 </ b> P fed by the preform feeding apparatus 20 is inserted into the furnace core tube 26. Is done. The heating element 27 is provided so as to heat the core tube 26 from the outer peripheral surface side of the core tube 26, and is, for example, a resistance type heating element. The heating element 27 may be a part of the furnace core tube 26. The core tube 26 and the heating element 27 are surrounded by a heat insulating material 28, and the heat generated by the heating element 27 can be used effectively.

  The maximum temperature in the heating furnace 25 is the size of the optical fiber preform 1P, the target outer diameter of the bare optical fiber 1N drawn from the optical fiber preform 1P, the tension applied to the bare optical fiber 1N, etc. However, the temperature may be as high as about 2000 ° C. Therefore, it is preferable that the material which comprises the core tube 26, the heat generating body 27, and the heat insulating material 28 is carbon, for example.

  The cooling device 30 is a device that is disposed below the heating furnace 25 and cools the optical fiber bare wire 1N formed by drawing the optical fiber preform 1P. An example of the cooling device 30 is a configuration in which the bare optical fiber 1N is surrounded by a member through which cooling water flows.

  The coating layer forming apparatus 40 is an apparatus that forms the resin coating layer 12 that covers the outer peripheral surface of the bare optical fiber 1N. In the present embodiment, the coating layer forming apparatus 40 includes an application unit 41 and a curing unit 42. The application unit 41 includes a first application unit 41F and a second application unit 41S, and the curing unit 42 includes a first curing unit 42F and a second curing unit 42S. In the first application section 41F, the outer peripheral surface of the bare optical fiber 1N is coated with the uncured inner resin that becomes the inner resin layer 13 on the outer peripheral surface of the bare optical fiber 1N, and the uncured inner resin is applied. An uncured outer resin to be the outer resin layer 14 is applied to the outer layer. Thus, the uncured inner resin and outer resin applied to the bare optical fiber 1N by the first application part 41F are cured by the first curing part 42F, and the inner resin layer 13 and the outer resin layer 14 are formed. . In the second application part 41S, an uncured protective resin to be the resin protective layer 15 is applied to the outer peripheral surface of the outer resin layer 14 thus formed. This uncured protective resin is cured by the second cured portion 42S, the protective resin is cured, and the resin protective layer 15 is formed.

  FIG. 3 is a diagram schematically illustrating the application unit illustrated in FIG. 2, and is a diagram schematically illustrating a vertical cross section of the application unit. As shown in FIG. 3, the application part 41 of this embodiment has the 1st application part 41F and the 2nd application part 41S as mentioned above. The first application unit 41F includes a first die body 43 in which a first storage chamber 44, a second storage chamber 45, and a third storage chamber 46 are formed, and a guide member 70 as main components. The first die body 43 has a first block 51, a second block 52, and a third block 53. The 2nd application part 41S is provided with the 2nd die main part 54 in which the 4th storage room 47 is formed as the main composition.

  The first block 51 of the first die body 43 in the first application part 41F has a cylindrical side wall part 51s extending in the vertical direction and a bottom wall part 51b closing the opening on the lower side of the side wall part 51s. The first die 55 is attached to the bottom wall portion 51b. The first die 55 is a substantially cylindrical member, and is fitted into a circular through hole formed in the bottom wall portion 51b and fixed to the bottom wall portion 51b. The lower portion of the first die 55 protrudes downward from the bottom wall portion 51b. The outer peripheral surface of the portion of the first die 55 that protrudes downward from the bottom wall portion 51b is inclined downward toward the center. Further, the inner peripheral surface of the first die 55 is inclined downward toward the center. For this reason, the part where the inner diameter of the first die 55 is minimum is the first die port 55H which is an opening at the lower end of the first die 55, and the diameter of the first die port 55H is outside the bare optical fiber 1N. It is assumed to be larger than the diameter. Such an internal space of the first block 51 serves as the first storage chamber 44. The upper portion of the first storage chamber 44 is opened to form an opening 44H, and the first storage chamber 44 has a first die port 55H below.

  An optical fiber bare wire 1N is passed through the first housing chamber 44 so as to pass through the upper opening 44H to the first die port 55H. The gap between the edge of the opening 44H and the outer peripheral surface of the bare optical fiber 1N is, for example, 10 mm or more. The diameter of the first die port 55H is, for example, larger than the outer diameter of the bare optical fiber 1N, and is not more than twice the outer diameter of the bare optical fiber 1N.

  The first storage chamber 44 is supplied with an uncured inner resin 61 that is a part of the inner resin layer 13 in the resin coating layer 12 from the upper opening 44H, and the inner resin 61 is stored therein. The liquid surface of the inner resin 61 in contact therewith is formed in the first storage chamber 44.

  The second block 52 of the first die body 43 includes a cylindrical side wall portion 52 s that is spaced from the outer peripheral surface of the side wall portion 51 s of the first block 51 and surrounds the side wall portion 51 s, and a bottom wall portion 51 b of the first block 51. A bottom wall portion 52b that is spaced apart from the lower surface and closes the opening on the lower side of the side wall portion 52s, and extends from the entire periphery of the upper end portion of the side wall portion 52s to the side wall portion 51s side of the first block 51 to the side wall portion 51s. And a top wall portion 52t to be connected. A second die 56 is attached to the bottom wall portion 52b. The second die 56 is a substantially cylindrical member, and is fitted into a circular through hole formed in the bottom wall portion 52b so that the center axis of the second die 56 is substantially coincident with the center axis of the first die 55. And fixed to the bottom wall portion 52b. The lower portion of the second die 56 projects downward from the bottom wall portion 52b. The outer peripheral surface of the portion of the second die 56 that protrudes downward from the bottom wall portion 52b is inclined downward toward the center. The inner peripheral surface of the second die 56 is inclined downward toward the center. For this reason, the part where the inner diameter of the second die 56 is minimum is the second die port 56 </ b> H which is an opening at the lower end of the second die 56. A space surrounded by the second block 52 and the first block 51 is the second storage chamber 45. The second storage chamber 45 communicates with the first storage chamber 44 via the first die port 55H and has a second die port 56H below. A resin supply port 64 that communicates with the second storage chamber 45 is formed in the top wall portion 52 t of the second block 52.

  As described above, since the second storage chamber 45 communicates with the first storage chamber 44 via the first die port 55H, the bare optical fiber 1N that has passed through the first die port 55H enters the second storage chamber 45. Inserted. That is, it can be understood that the first die port 55H also serves as a first insertion port for inserting the bare optical fiber 1N into the second storage chamber 45. Then, the bare optical fiber 1N that has passed through the first accommodation chamber 44 is passed through the second accommodation chamber 45 so as to pass from the first die port 55H serving as the first insertion port to the second die port 56H. The diameter of the second die port 56H is, for example, larger than the outer diameter of the bare optical fiber 1N, and is not more than twice the outer diameter of the bare optical fiber 1N.

  The second storage chamber 45 is supplied with an uncured inner resin 61 that is another part of the inner resin layer 13 in the resin coating layer 12 from the resin supply port 64 so that the inner resin 61 has a predetermined pressure. Filled with. For this reason, the inside of the second storage chamber 45 is filled with the inner resin 61, and the liquid surface in contact with the gas of the inner resin 61 is not formed in the second storage chamber 45. In the present embodiment, the pressure of the inner resin 61 filled in the second storage chamber 45 is larger than the pressure in the vicinity of the first die port 55 </ b> H in the inner resin 61 stored in the first storage chamber 44.

  The third block 53 of the first die body 43 includes a cylindrical side wall portion 53 s that is separated from the outer peripheral surface of the side wall portion 52 s of the second block 52 and surrounds the side wall portion 52 s, and a bottom wall portion 52 b of the second block 52. A bottom wall portion 53b that is spaced apart from the lower surface and closes the opening on the lower side of the side wall portion 53s, and extends from the entire periphery of the upper end portion of the side wall portion 53s to the side wall portion 52s side of the second block 52 to the side wall portion 52s. And a top wall portion 53t to be connected. A third die 57 is attached to the bottom wall portion 53b. The third die 57 is a substantially cylindrical member, and is fitted into a circular through hole formed in the bottom wall portion 53b so that the center axis of the third die 57 substantially coincides with the center axis of the second die 56. And fixed to the bottom wall portion 53b. The lower portion of the third die 57 projects downward from the bottom wall portion 53b. The outer peripheral surface of the portion of the third die 57 that protrudes downward from the bottom wall portion 53b is inclined downward toward the center. The inner peripheral surface of the third die 57 is inclined downward toward the center. For this reason, the portion where the inner diameter of the third die 57 is the smallest is the third die port 57 </ b> H that is the opening at the lower end of the third die 57. A space enclosed by the third block 53 and the side wall 52s and the bottom wall 53b of the second block 52 is defined as a third storage chamber 46. The third storage chamber 46 communicates with the second storage chamber 45 through the second die port 56H, and has a third die port 57H below. A resin supply port 65 communicating with the third storage chamber 46 is formed in the top wall portion 53 t of the third block 53.

  As described above, since the third storage chamber 46 communicates with the second storage chamber 45 through the second die port 56H, the bare optical fiber 1N that has passed through the second die port 56H enters the third storage chamber 46. Inserted. That is, it can be understood that the second die port 56H also serves as a second insertion port for inserting the bare optical fiber 1N into the third housing chamber 46. Then, the bare optical fiber 1N that has passed through the second storage chamber 45 is passed through the third storage chamber 46 so as to pass from the second die port 56H as the second insertion port to the third die port 57H. The diameter of the third die port 57H is, for example, larger than the diameter of the second die port 56H, and is not more than twice the diameter of the second die port 56H.

  The third storage chamber 46 is supplied with an uncured outer resin 62 that becomes the outer resin layer 14 in the resin coating layer 12 from the resin supply port 65 and is filled with the outer resin 62 at a predetermined pressure. For this reason, the inside of the third storage chamber 46 is filled with the outer resin 62, and the liquid surface in contact with the gas of the outer resin 62 is not formed in the third storage chamber 46. In the present embodiment, the pressure of the outer resin 62 filled in the third storage chamber 46 is larger than the pressure in the vicinity of the first die port 55 </ b> H in the inner resin 61 stored in the first storage chamber 44. Further, the pressure of the outer resin 62 filled in the third storage chamber 46 is set lower than the pressure of the inner resin 61 filled in the second storage chamber 45.

  The second die body 54 of the second application part 41S is separated from the first die body 43 of the first application part 41F, and is disposed below the first die body 43. The second die body 54 includes a cylindrical side wall 54s extending in the vertical direction, a bottom wall 54b that closes an opening on the lower side of the side wall 54s, and a top that closes an opening on the upper side of the side wall 54s. Wall part 54t. A fourth die 58 is attached to the bottom wall portion 54b, and a nipple 59 is attached to the top wall portion 54t. The fourth die 58 is a substantially cylindrical member, and is fitted into a circular through hole formed in the bottom wall portion 54b so that the central axis of the fourth die 58 is substantially coincident with the central axis of the third die 57. And fixed to the bottom wall portion 54b. The lower portion of the fourth die 58 protrudes downward from the bottom wall portion 54b. The outer peripheral surface of the portion of the fourth die 58 that protrudes downward from the bottom wall portion 54b is inclined downward toward the center. The inner peripheral surface of the fourth die 58 is inclined downward toward the center. For this reason, the portion where the inner diameter of the fourth die 58 is the smallest is the fourth die opening 58H which is the opening at the lower end of the fourth die 58. The nipple 59 is a substantially cylindrical member, and is fitted into a circular through-hole formed in the top wall portion 54t so that the central axis of the nipple 59 substantially coincides with the central axis of the third die 57. It is fixed at 54t. The lower part of such a nipple 59 protrudes downward from the top wall part 54t. The outer peripheral surface of the portion of the nipple 59 that protrudes downward from the top wall portion 54t is inclined downward toward the center. Further, the inner peripheral surface of the nipple 59 is inclined downward toward the center. For this reason, the part where the inner diameter of the nipple 59 becomes the minimum is the third insertion port 59 </ b> H which is an opening at the lower end of the nipple 59. The internal space of the second die main body 54 is a fourth storage chamber 47, and the fourth storage chamber 47 has a third insertion port 59H on the upper side and a fourth die port 58H on the lower side. A resin supply port 66 that communicates with the fourth storage chamber 47 is formed in the top wall portion 54 t of the second die body 54.

  The bare optical fiber 1N that has passed through the third housing chamber 46 is passed through the fourth housing chamber 47 so as to come out from the third insertion port 59H to the fourth die port 58H. In this way, the bare optical fiber 1N sequentially passes through the first storage chamber 44, the second storage chamber 45, the third storage chamber 46, and the fourth storage chamber 47. The diameter of the third insertion port 59H is, for example, larger than the diameter of the third die port 57H, and is not more than 5 times the diameter of the third die port 57H. The diameter of the fourth die port 58H is, for example, larger than the diameter of the third die port 57H, and is not more than twice the diameter of the third die port 57H.

  The fourth storage chamber 47 is supplied with an uncured protective resin 63 that becomes the resin protective layer 15 in the resin coating layer 12 from the resin supply port 66 and is filled with the protective resin 63 at a predetermined pressure. For this reason, the inside of the fourth storage chamber 47 is filled with the protective resin 63, and the liquid surface in contact with the gas of the protective resin 63 is not formed in the fourth storage chamber 47. The protective resin 63 may overflow from the third insertion port 59H of the nipple 59 to the outside of the fourth storage chamber 47. In the present embodiment, the pressure of the protective resin 63 filled in the fourth storage chamber 47 is larger than the pressure in the vicinity of the first die port 55 </ b> H in the inner resin 61 stored in the first storage chamber 44. However, the pressure of the protective resin 63 is not particularly limited.

  FIG. 4 is a perspective view schematically showing the guide member shown in FIG. The guide member 70 of the present embodiment is a cylindrical member extending in the vertical direction. On the side surface of the guide member 70, three slits 71 are formed as communication portions that communicate the outer region and the inner region of the guide member 70. The three slits 71 extend upward from the lower end of the guide member 70 to a predetermined position, and are formed so as to be positioned at approximately equal intervals in the circumferential direction of the guide member 70. As shown in FIG. 3, the guide member 70 has at least the slit 71 in the inner resin 61 stored in the first storage chamber 44 while the lower end is separated from the bottom wall portion 51 b of the first block 51. A part of the optical fiber bare wire 1N is disposed so as to pass through the region inside the guide member 70. The guide member 70 disposed in this manner surrounds the bare optical fiber 1N at a distance from the outer peripheral surface of the bare optical fiber 1N in at least the inner resin 61 stored in the first storage chamber 44. The inner diameter of the guide member 70 is set to a predetermined value between the inner peripheral surface of the guide member 70 and the outer peripheral surface of the bare optical fiber 1N when the bare optical fiber 1N is inserted into a region inside the guide member 70. The diameter is such that a gap, for example, a gap of 5 mm or more is formed. Further, by arranging the guide member 70 in this way, the inner resin 61 can flow into the region inside the guide member 70 from the slit 71 or the opening at the lower end of the guide member 70. That is, the guide member 70 can allow the inner resin 61 to flow into a region inside the guide member 70.

  The curing unit 42 shown in FIG. 2 includes the first curing unit 42F and the second curing unit 42S as described above. The first curing unit 42F is disposed between the first application unit 41F and the second application unit 41S. For example, when the inner resin 61 and the outer resin 62 applied to the bare optical fiber 1N by the first application unit 41F are ultraviolet curable resins, the first curing unit 42F is coated with the inner resin 61 and the outer resin 62. In addition, the optical fiber bare wire 1N is irradiated with ultraviolet rays. On the other hand, when the inner resin 61 and the outer resin 62 applied to the bare optical fiber 1N by the first application part 41F are thermosetting resins, the inner resin 61 and the outer resin 62 are applied to the first cured part 42F. It is set as the apparatus which heats the optical fiber bare wire 1N made. When one of the inner resin 61 and the outer resin 62 applied to the bare optical fiber 1N by the first application part 41F is an ultraviolet curable resin and the other is a thermosetting resin, the first curing part 42F is The optical fiber bare wire 1N coated with the inner resin 61 and the outer resin 62 is irradiated with ultraviolet rays and heated.

  The second curing unit 42S is disposed below the second application unit 41S. For example, when the protective resin 63 applied to the bare optical fiber 1N by the second application unit 41S is an ultraviolet curable resin, the second cured portion 42S is not irradiated to the bare optical fiber 1N coated with the protective resin 63. It is set as the apparatus which irradiates. On the other hand, when the protective resin 63 applied to the bare optical fiber 1N by the second application part 41S is a thermosetting resin, the second cured part 42S is applied to the bare optical fiber 1N to which the protective resin 63 is applied. It is a device that applies heat.

  The take-up device 81 is a device that takes up the optical fiber 1 whose direction has been changed by the turn pulley 80 at a predetermined take-up speed, and the take-up device 82 is a device that winds the optical fiber 1 around a bobbin.

  Next, the manufacturing method of the optical fiber which concerns on embodiment of this invention is demonstrated.

  FIG. 5 is a flowchart showing a method for manufacturing an optical fiber according to an embodiment of the present invention. The optical fiber 1 is manufactured using the optical fiber manufacturing apparatus 100 by the optical fiber manufacturing method of the present embodiment. As shown in FIG. 5, the manufacturing method of the optical fiber 1 of the present embodiment includes a preparation process P1, a drawing process P2, a cooling process P3, a first resin application process P4, and a second resin application process P5. The third resin coating process P6, the first curing process P7, the fourth resin coating process P8, and the second curing process P9 are provided as main processes.

<Preparation process P1>
In this step, first, an optical fiber preform 1P having a core glass body to be the core 10 of the optical fiber 1 and a clad glass body to be the cladding 11 is prepared. FIG. 6 is a view showing a cross section perpendicular to the longitudinal direction of the optical fiber preform 1P prepared in the preparation step P1. As shown in FIG. 6, the optical fiber preform 1 </ b> P has a core glass body 10 </ b> P that becomes the core 10 of the optical fiber 1 and a clad glass body 11 </ b> P that becomes the clad 11. The core glass body 10P is disposed at the center of the clad glass body 11P. In the cross section perpendicular to the longitudinal direction, the outer periphery of the clad glass body 11P is approximately a regular heptagon. That is, the outer shape of the optical fiber preform 1P in a cross section perpendicular to the longitudinal direction is approximately a regular heptagon. The manufacturing method of the optical fiber preform 1P is not particularly limited. For example, an optical fiber base material having a circular outer shape is manufactured by an MCVD method (Modified Chemical Vapor Deposition Method), and the optical fiber base material having a substantially regular heptagonal shape is cut by cutting the optical fiber base material having a circular outer shape. 1P is produced.

  Next, the optical fiber preform 1 </ b> P is installed in the heating furnace 25. As shown in FIG. 2, the upper end portion of the optical fiber preform 1P is fixed to the preform delivery device 20, and the optical fiber preform 1P is inserted into the core tube 26 of the heating furnace 25 from the lower end portion.

<Drawing process P2>
This step is a step of drawing the lower end portion of the optical fiber preform 1P while heating it in the heating furnace 25.

  As described above, the optical fiber preform 1P is installed in the heating furnace 25 in the preparation step P1. In the present embodiment, the optical fiber preform 1P installed in this manner is rotated around the central axis Pa of the optical fiber preform 1P. Further, the heating element 27 of the heating furnace 25 is caused to generate heat to heat the lower end portion of the rotating optical fiber preform 1P. The lower end portion of the optical fiber preform 1P is heated in the heating furnace 25 to be in a molten state, a tapered neck-down ND is formed to reduce the diameter, and the glass fiber is drawn from the heating furnace 25. When the drawn glass wire comes out of the heating furnace 25, it immediately solidifies and becomes a bare optical fiber 1 </ b> N composed of the core 10 and the clad 11. As described above, the core glass body 10P is disposed at the center of the clad glass body 11P, and the optical fiber preform 1P is rotated around the central axis Pa of the optical fiber preform 1P and drawn. For this reason, permanent twist about the central axis of the core 10 is given to this optical fiber bare wire 1N. In addition, since the outer shape of the optical fiber preform 1P in the cross section perpendicular to the longitudinal direction is substantially a regular heptagon as described above, the outer shape of the bare optical fiber 1N in the cross section perpendicular to the longitudinal direction is substantially a regular heptagon. The

  The amount of twist imparted to the bare optical fiber 1N is determined by the take-up speed of the optical fiber 1 by the take-up device 81 and the optical fiber preform 1P by the preform delivery device 20 around the central axis Pa of the optical fiber preform 1P. It is adjusted by adjusting the rotation speed.

<Cooling process P3>
This step is a step of cooling the bare optical fiber 1N to an appropriate temperature. The bare optical fiber 1N is cooled by passing through the cooling device 30. When entering the cooling device 30, the temperature of the bare optical fiber 1 N is about 200 ° C., for example, but when leaving the cooling device 30, the temperature of the bare optical fiber 1 N is, for example, 20 ° C. to 50 ° C. .

<First resin application process P4>
This step is a step of applying the uncured inner resin 61 that becomes a part of the inner resin layer 13 to the outer peripheral surface of the bare optical fiber 1N.

  First, as a preparatory stage for performing the first resin coating process P4, the bare optical fiber 1N sent from the cooling device 30 is applied to the coating section 41 in a state where no resin is stored in each of the storage chambers 44, 45, 46, and 47. Pass through. Specifically, the bare optical fiber 1N is inserted into the first storage chamber 44 from above the first storage chamber 44 and passed through the first die port 55H. At this time, the bare optical fiber 1N is passed through a region inside the guide member 70. Since the first storage chamber 44 and the second storage chamber 45 communicate with each other via the first die port 55H, the bare optical fiber 1N that has passed through the first die port 55H is inserted into the second storage chamber 45. . The bare optical fiber 1N inserted into the second storage chamber 45 is passed through the second die port 56H. Since the second storage chamber 45 and the third storage chamber 46 communicate with each other via the second die port 56H, the optical fiber bare wire 1N that has passed through the second die port 56H is inserted into the third storage chamber 46. . The bare optical fiber 1N inserted into the third storage chamber 46 is passed through the third die port 57H and taken out from the third storage chamber 46. The bare optical fiber 1N that has come out of the third storage chamber 46 is inserted into the fourth storage chamber 47 through the third insertion port 59H, passes through the fourth die port 58H, and exits from the fourth storage chamber 47. In this manner, the fed bare optical fiber 1N passes through the first storage chamber 44, the second storage chamber 45, the third storage chamber 46, and the fourth storage chamber 47 sequentially.

  Moreover, resin is accommodated in each accommodation chamber 44, 45, 46, 47. First, the uncured protective resin 63 serving as the resin protective layer 15 is supplied to the fourth storage chamber 47 in which the die port is located at the lowest position, and the protective resin 63 is filled into the fourth storage chamber 47 with a predetermined pressure. Next, the uncured outer resin 62 that becomes the outer resin layer 14 is supplied to the third housing chamber 46 in which the die port is located above the fourth die port 58H of the fourth housing chamber 47, so that the outer resin 62 is removed. 3 The storage chamber 46 is filled with a predetermined pressure. Next, the uncured inner resin 61 that is another part of the inner resin layer 13 is supplied to the second housing chamber 45 where the die port is located above the third die port 57H of the third housing chamber 46. The inner resin 61 is filled into the second storage chamber 45 with a predetermined pressure. Next, the uncured inner resin 61 that becomes a part of the inner resin layer 13 is supplied to the first housing chamber 44 in which the die port is located above the second die port 56H of the second housing chamber 45 to the inner side. Resin 61 is stored in the first storage chamber 44. In this manner, the resin is accommodated in each of the accommodation chambers 44, 45, 46, 47. In addition, the time which begins to supply resin to each storage chamber 44, 45, 46, 47 is not specifically limited. However, as described above, it is preferable to supply the resin in the order of the third storage chamber 46, the second storage chamber 45, and the first storage chamber 44 from the fourth storage chamber 47 where the die port is located at the lowest position. By doing so, the inner resin 61 flows into the third storage chamber 46 and the inner resin 61 and the outer resin 62 are mixed, or the inner resin 61 and the outer resin 62 flow into the fourth storage chamber 47. Mixing of the inner resin 61 or the outer resin 62 and the protective resin 63 can be suppressed.

  In this manner, as shown in FIG. 3, the bare optical fiber 1N sequentially passes through the first storage chamber 44, the second storage chamber 45, the third storage chamber 46, and the fourth storage chamber 47, and each storage The chambers 44, 45, 46, 47 are made to contain resin. By doing so, the bare optical fiber 1N passes through the first storage chamber 44 in which the uncured inner resin 61 is stored. That is, the optical fiber bare wire 1N is inserted from above the first storage chamber 44 into the first storage chamber 44 in which the uncured inner resin 61 that becomes a part of the inner resin layer 13 is stored. It will be extracted from 55H. As described above, since the diameter of the first die port 55H is larger than the outer diameter of the bare optical fiber 1N, there is a gap between the outer peripheral surface of the bare optical fiber 1N and the edge of the first die port 55H. Is formed. Therefore, by pulling out the bare optical fiber 1N from the first die port 55H, the inner resin 61 is poured out from this gap, and the inner resin 61 is applied to the outer peripheral surface of the bare optical fiber 1N. The thickness of the inner resin 61 applied in this way is approximately the same as the width of the gap, and the outer diameter of the bare optical fiber 1N coated with the inner resin 61 is approximately the same as the diameter of the first die port 55H. Is done. The inner resin 61 is stored in the first storage chamber 44 that opens upward. For this reason, when the bare optical fiber 1N passes through the first housing chamber 44, convection Cf is generated in the inner resin 61 around the bare optical fiber 1N. This convection Cf is a circular flow that goes downward on the bare optical fiber 1N side and goes upward on the opposite side of the bare optical fiber 1N side. Then, a meniscus Me that is recessed in a concave shape around the bare optical fiber 1N is formed on the liquid surface of the inner resin 61. In the present embodiment, as described above, the guide member 70 that surrounds the bare optical fiber 1N in the inner resin 61 is disposed. For this reason, this convection Cf is regulated so as to be formed in the region closer to the bare optical fiber 1N than the guide member 70, and the meniscus Me is also formed in the region closer to the bare optical fiber 1N than the guide member 70. It is regulated to be. For this reason, compared with the case where the guide member 70 is not disposed, the region of the inner resin 61 where the convection Cf is generated can be narrowed to reduce the concave meniscus Me, thereby stabilizing the convection Cf. The slit 71 formed on the side surface of the guide member 70 is located in the inner resin 61 as described above. Therefore, the inner resin 61 can go back and forth between the outer region of the guide member 70 and the inner region of the guide member 70 through the slit 71. Further, the lower end of the guide member 70 is separated from the bottom wall portion 51 b of the first block 51. For this reason, the inner resin 61 can go back and forth between a region outside the guide member 70 and a region inside the guide member 70 through the opening on the lower side of the guide member 70.

<Second resin application process P5>
In this step, the other part of the inner resin layer 13 is formed on the outer peripheral surface of the bare optical fiber 1N coated with the uncured inner resin 61 that becomes a part of the inner resin layer 13 in the first resin application step P4. In this step, the uncured inner resin 61 is applied.

  As described above, the inner resin 61 is filled in the second storage chamber 45 at a predetermined pressure, so that the bare optical fiber 1N coated with the inner resin 61 in the first resin coating step P4 is uncured inner resin. 61 passes through the second storage chamber 45 filled with a predetermined pressure. That is, the bare optical fiber 1N coated with the inner resin 61 in the first resin coating step P4 is filled with the uncured inner resin 61 that is another part of the inner resin layer 13 with a predetermined pressure. 2 Inserted into the storage chamber 45 from the first die port 55H and extracted from the second die port 56H. As described above, the diameter of the second die port 56H is larger than the outer shape of the bare optical fiber 1N. For example, when the diameter of the second die port 56H is larger than the diameter of the first die port 55H, the outer peripheral surface of the bare optical fiber 1N coated with the inner resin 61 in the first resin coating step P4 and the second A gap is formed between the edge of the die port 56H. In FIG. 3, the outer peripheral surface of the bare optical fiber 1N coated with the inner resin 61 in the first resin coating step P4 is indicated by a broken line. Therefore, by pulling out the bare optical fiber 1N from the second die port 56H, the inner resin 61 is poured out from this gap, and the outer peripheral surface of the bare optical fiber 1N coated with the inner resin 61 in the first resin coating step P4. The inner resin 61 is applied to the surface. Thus, the entire thickness of the inner resin 61 applied to the bare optical fiber 1N is substantially the same as the gap between the outer peripheral surface of the bare optical fiber 1N and the edge of the second die port 56H. Adjusted. On the other hand, when the diameter of the second die port 56H is smaller than the diameter of the first die port 55H, a part of the inner resin 61 applied to the outer peripheral surface of the bare optical fiber 1N in the first resin application step P4. Peels off. Here, in the second storage chamber 45, the inner resin 61 is filled with a predetermined pressure. Therefore, the inner resin 61 filled in the second storage chamber 45 is applied to the bare optical fiber 1N, and the entire thickness of the inner resin 61 applied to the bare optical fiber 1N is the outer peripheral surface of the bare optical fiber 1N. And the gap between the second die port 56H and the edge of the second die port 56H. In this manner, the outer diameter of the bare optical fiber 1N coated with the inner resin 61 in this step is made substantially the same as the diameter of the second die port 56H.

<Third resin application step P6>
In this step, the uncured outer resin layer 14 is applied to the outer peripheral surface of the bare optical fiber 1N coated with the uncured inner resin 61 that is another part of the inner resin layer 13 in the second resin coating step P5. In this step, the outer resin 62 is applied.

  As described above, the outer resin 62 is filled into the third storage chamber 46 at a predetermined pressure, so that the bare optical fiber 1N coated with the inner resin 61 in the second resin coating step P5 is uncured outer resin. 62 passes through the third storage chamber 46 filled with a predetermined pressure. That is, the bare optical fiber 1N coated with the inner resin 61 in the second resin coating process P5 is filled in the third storage chamber 46 filled with the uncured outer resin 62 that becomes the outer resin layer 14 with a predetermined pressure. Then, it is inserted from the second die port 56H and extracted from the third die port 57H. Since the diameter of the third die port 57H is larger than the diameter of the second die port 56H as described above, the outer peripheral surface of the bare optical fiber 1N coated with the inner resin 61 in the second resin coating step P5 A gap is formed between the edge of the third die port 57H. Therefore, by pulling out the bare optical fiber 1N from the third die port 57H, the outer resin 62 is poured out from this gap, and the outer peripheral surface of the bare optical fiber 1N coated with the inner resin 61 in the second resin coating step P5. The outer resin 62 is applied to the surface. The thickness of the outer resin 62 applied in this manner is substantially the same as the width of the gap, and the outer diameter of the bare optical fiber 1N to which the outer resin 62 is applied in this process is equal to the diameter of the third die port 57H. It is almost the same.

<First curing step P7>
This step is a step of curing the uncured inner resin 61 and outer resin 62 applied to the bare optical fiber 1N. The uncured inner resin 61 and outer resin 62 applied to the bare optical fiber 1N are cured by the first curing portion 42F, the inner resin 61 becomes the inner resin layer 13, and the outer resin 62 becomes the outer resin layer 14. .

<Fourth resin application process P8>
This step is a step of applying the protective resin 63 that becomes the uncured resin protective layer 15 to the outer peripheral surface of the bare optical fiber 1N in which the inner resin 61 and the outer resin 62 are cured in the first curing step P7.

  As described above, the protective resin 63 is filled in the fourth storage chamber 47 with a predetermined pressure, so that the bare optical fiber 1N in which the inner resin 61 and the outer resin 62 are cured in the first curing process P7 is in an uncured state. The protective resin 63 passes through the fourth storage chamber 47 filled with a predetermined pressure. In other words, in the first curing step P7, the optical fiber bare wire 1N in which the inner resin 61 and the outer resin 62 are cured is filled with the uncured protective resin 63 serving as the resin protective layer 15 with a predetermined pressure. The chamber 47 is inserted from the third insertion port 59H and extracted from the fourth die port 58H. As described above, since the diameter of the fourth die port 58H is larger than the diameter of the third die port 57H, the optical fiber bare wire 1N in which the inner resin 61 and the outer resin 62 are cured in the first curing step P7. A gap is formed between the outer peripheral surface and the edge of the fourth die opening 58H. For this reason, by pulling out the bare optical fiber 1N from the fourth die port 58H, the protective resin 63 is poured from this gap, and the inner resin 61 and the outer resin 62 are cured in the first curing step P7. A protective resin 63 is applied to the outer peripheral surface of the substrate. The thickness of the protective resin 63 applied in this way is approximately the same as the width of the gap, and the outer diameter of the bare optical fiber 1N coated with the protective resin 63 by this process is equal to the diameter of the fourth die port 58H. It is almost the same.

<Second curing step P9>
This step is a step of curing the uncured protective resin 63 applied to the bare optical fiber 1N. The uncured protective resin 63 applied to the bare optical fiber 1N is cured by the second cured portion 42S, the protective resin 63 becomes the resin protective layer 15, and the resin coating layer 12 is formed. As a result, the bare optical fiber 1N becomes the optical fiber 1 shown in FIG.

  The direction of the optical fiber 1 is changed by the turn pulley 80 and is taken up by the take-up device 82.

  As described above, in the method of manufacturing the optical fiber 1 according to the present embodiment, the preparation process P1, the drawing process P2, the cooling process P3, the first resin application process P4, the second resin application process P5, and the third resin application process. The optical fiber 1 shown in FIG. 1 is manufactured through P6, the 1st hardening process P7, the 4th resin application | coating process P8, and the 2nd hardening process P9.

  In the manufacturing method of the present embodiment, the uncured inner resin 61 that becomes the inner resin layer 13 is applied to the outer peripheral surface of the bare optical fiber 1N by the first resin application step P4 and the second resin application step P5. In addition, the uncured outer resin 62 to be the outer resin layer 14 is applied to the outer peripheral surface of the bare optical fiber 1N to which the uncured inner resin 61 has been applied in the third resin application step P6. The uncured inner resin 61 and outer resin 62 applied in this manner are cured to form the inner resin layer 13 and the outer resin layer 14. In the manufacturing method of the present embodiment, the bare optical fiber 1N is passed through the first storage chamber 44, the second storage chamber 45, and the third storage chamber 46 in this order, and the upper portion of the first storage chamber is open. For this reason, as compared with the case where the first storage chamber 44 is filled with the uncured inner resin 61 as in the manufacturing method described in Patent Document 1, the optical fiber bare wire 1N is perpendicular to the longitudinal direction. Even if the fluctuation occurs, it is possible to prevent the outer peripheral surface of the bare optical fiber 1N from coming into contact with the first die body 43 in which the first storage chamber 44 is formed and damage the outer peripheral surface of the bare optical fiber 1N. it can. Therefore, the manufacturing method of this embodiment can suppress that the mechanical strength of the optical fiber 1 falls.

  Further, in the manufacturing method of the present embodiment, in the second resin application step P5, the inner resin layer 13 is filled in the second storage chamber 45 filled with the inner resin 61 that is another part of the inner resin layer 13 at a predetermined pressure. The bare optical fiber 1N coated with the inner resin 61 that is a part of is passed through. Then, the inner resin 61 serving as another part of the inner resin layer 13 is applied to the outer peripheral surface of the bare optical fiber 1N to which the inner resin 61 serving as a part of the inner resin layer 13 is applied. Since the second storage chamber 45 is filled with the inner resin 61 at a predetermined pressure, the second housing chamber 45 is poured from the second die port 56H together with the bare optical fiber 1N coated with the inner resin 61 that becomes a part of the inner resin layer 13. Fluctuations in the pressure of the uncured inner resin 61 that is discharged are suppressed. Therefore, even if a deviation occurs in the thickness of the inner resin 61 applied to the outer peripheral surface of the bare optical fiber 1N in the first resin coating step P4, the inner side is so arranged that the deviation is leveled in the second resin coating step P5. Resin 61 can be applied, and deviation in the thickness of the inner resin layer 13 can be suppressed. In the third resin coating step P6, the inner resin 61 is applied by passing the bare optical fiber 1N coated with the inner resin 61 through the third housing chamber 46 filled with the outer resin 62 at a predetermined pressure. The outer resin 62 is applied to the outer peripheral surface of the bare optical fiber 1N. For this reason, unevenness in the thickness of the outer resin layer 14 is suppressed. Thus, in the manufacturing method of this embodiment, it can suppress that the thickness of the resin coating layer 12 produces unevenness.

  Further, in the manufacturing method of the present embodiment, at least in the inner resin 61 accommodated in the first accommodation chamber 44, a cylindrical guide member 70 that surrounds the optical fiber bare wire 1N while being separated from the outer peripheral surface of the bare optical fiber 1N. Is placed. The guide member 70 can allow the inner resin 61 to flow into a region inside the guide member 70.

  By doing so, as described above, the convection Cf generated in the inner resin 61 stored in the first storage chamber 44 can be formed in the region closer to the bare optical fiber 1N than the guide member 70. . For this reason, compared with the case where the guide member 70 is not disposed, the region of the inner resin 61 where the convection Cf is generated can be narrowed to reduce the concave meniscus Me, thereby stabilizing the convection Cf. For this reason, in the 1st resin application | coating process P4, it can suppress that the thickness of the inner side resin 61 apply | coated to the outer peripheral surface of the optical fiber bare wire 1N arises.

  In the manufacturing method of the present embodiment, the guide member 70 is disposed before the inner resin 61 is stored in the first storage chamber 44. For this reason, compared with the case where the guide member 70 is arrange | positioned after storing the inner side resin 61 in the 1st storage chamber 44, the guide member 70 can be arrange | positioned easily.

  Further, in the manufacturing method of the present embodiment, the side surface of the guide member 70 is formed with a slit 71 as a communication portion that connects the outer region and the inner region of the guide member 70 in the inner resin 61. . For this reason, compared with the case where the slit 71 is not formed on the side surface of the guide member 70, the inner resin 61 positioned in the outer region of the guide member 70 can be easily flown into the inner region of the guide member 70, The convection Cf in the inner resin 61 stored in the first storage chamber 44 can be further stabilized. For this reason, it can suppress more that the thickness of the inner side resin 61 apply | coated to the outer peripheral surface of the optical fiber bare wire 1N in the 1st resin application | coating process P4 arises.

  In the manufacturing method of the present embodiment, the resin constituting the inner resin layer 13 is a resin having a refractive index lower than that of the clad 11. Therefore, the optical fiber 1 having a double clad structure in which the clad 11 of the bare optical fiber 1N is the inner clad and the inner resin layer 13 is the outer clad can be manufactured.

  Moreover, in the manufacturing method of this embodiment, the core 10 consists of silica glass containing the active element excited by excitation light. For this reason, the manufacturing method of this embodiment can manufacture the optical fiber for amplification of a double clad structure.

  Further, the manufacturing method of the present embodiment includes a drawing process P2 in which the optical fiber preform 1P is drawn around the central axis Pa of the optical fiber preform 1P to form the bare optical fiber 1N. . For this reason, permanent twist can be given to the optical fiber bare wire 1N. For example, as in this embodiment, in an optical fiber for amplification having a double clad structure in which the clad 11 of the bare optical fiber 1N is an inner clad and the inner resin 13 layer is an outer clad, the optical fiber bare wire 1N is permanently attached. By imparting a proper twist, it is possible to make the light propagating through the clad 11 as the inner clad easily incident on the core 10 while suppressing the skew light. For this reason, the absorption efficiency of the excitation light in the amplification optical fiber having the double clad structure can be increased. When the optical fiber preform 1P is drawn while being rotated around the central axis Pa of the optical fiber preform 1P, the optical fiber bare wire 1N tends to be easily shaken in a direction perpendicular to the longitudinal direction. is there. However, as described above, according to the optical fiber manufacturing method of the present embodiment, the mechanical strength of the optical fiber is improved even when the bare optical fiber 1N is shaken in the direction perpendicular to the longitudinal direction. It can suppress that it falls. For this reason, the optical fiber manufacturing method of this embodiment forms the bare optical fiber 1N by drawing the optical fiber preform 1P around the central axis Pa of the optical fiber preform 1P in this way. This is especially useful when

  In the manufacturing method of the present embodiment, the outer shape of the bare optical fiber 1N in the cross section perpendicular to the longitudinal direction is non-circular. By making the outer shape of the bare optical fiber 1N non-circular, the light propagating in the cladding 11 can be repeatedly reflected while changing the reflection angle on the outer circumferential surface of the cladding 11 that is the outer circumferential surface of the bare optical fiber 1N. Light propagating through the cladding 11 can be easily incident on the core 10. Therefore, the manufacturing method according to the present embodiment manufactures an optical fiber for amplification having a double clad structure capable of suppressing skew light as compared with the case where the outer shape of the bare optical fiber 1N in a cross section perpendicular to the longitudinal direction is circular. Can do.

  In the manufacturing method of the present embodiment, the first die port 55H of the first storage chamber 44 also serves as a first insertion port for inserting the bare optical fiber 1N into the second storage chamber 45. For this reason, in the manufacturing method of this embodiment, the optical fiber bare wire 1N passes through the first die port 55H and is coated with the inner resin 61 that becomes a part of the inner resin layer 13 and is inserted into the second storage chamber 45. Is done. For this reason, even if the bare optical fiber 1N is shaken in the direction perpendicular to the longitudinal direction, the first die port 55H of the first storage chamber 44 does not serve as the first insertion port of the second storage chamber 45. As compared with the above, it is possible to suppress the inner resin 61 applied to the bare optical fiber 1N from coming into contact with the edge of the first insertion port of the second storage chamber 45. Therefore, as compared with the case where the first die port 55H does not also serve as the first insertion port of the second storage chamber 45, even if the bare optical fiber 1N is shaken in the direction perpendicular to the longitudinal direction, the bare optical fiber It is possible to further suppress the occurrence of unevenness in the thickness of the inner resin 61 applied to the wire 1N.

  In the manufacturing method of the present embodiment, the second die port 56H of the second storage chamber 45 also serves as a second insertion port for inserting the bare optical fiber 1N into the third storage chamber 46. For this reason, in the manufacturing method of this embodiment, the optical fiber bare wire 1N is applied with the inner resin 61 that is another part of the inner resin layer 13 by passing through the second die port 56H and the third storage chamber 46. Inserted into. For this reason, even if the optical fiber bare wire 1N is shaken in the direction perpendicular to the longitudinal direction, the second die port 56H of the second storage chamber 45 may not serve as the second insertion port of the third storage chamber 46. As compared with the above, the inner resin 61 applied to the bare optical fiber 1N can be prevented from coming into contact with the edge of the second insertion port of the third storage chamber 46. Therefore, compared to the case where the second die port 56H does not also serve as the insertion port of the third housing chamber 46, even if the optical fiber bare wire 1N is shaken in the direction perpendicular to the longitudinal direction, the bare optical fiber 1N It is possible to further suppress the occurrence of unevenness in the thickness of the inner resin 61 applied to the substrate.

  When the second die port 56H also serves as the second insertion port of the third storage chamber 46 as in the present embodiment, the pressure of the outer resin 62 filled in the third storage chamber 46 is applied to the second storage chamber 45. The pressure is preferably smaller than the pressure of the inner resin 61 to be filled. By doing in this way, it can suppress that the outer side resin 62 with which the 3rd storage chamber 46 is filled flows into the 2nd storage chamber 45. FIG. In addition, compared with the case where the pressure of the outer resin 62 filled in the third storage chamber 46 is larger than the pressure of the inner resin 61 filled in the second storage chamber 45, it is applied to the bare optical fiber 1N. The thickness of the inner resin 61 can be increased.

  In addition, since the manufacturing method of the present embodiment further includes the fourth resin coating step P8, the optical fiber 1 having the resin coating layer 12 including three resin layers can be manufactured.

  In addition, the manufacturing apparatus 100 for the optical fiber 1 according to this embodiment includes a first die body 43 including a first storage chamber 44, a second storage chamber 45, and a third storage chamber 46. The upper portion of the first storage chamber 44 is opened, and the first storage chamber 44 has a first die port 55H below. The second storage chamber 45 has a first die port 55H as an insertion port on the upper side and a second die port 56H on the lower side. The third storage chamber 46 has a second die port 56H as an insertion port on the upper side and a third die port 57H on the lower side. The first storage chamber 44 stores the inner resin 61 that is a part of the inner resin layer 13, and the second storage chamber 45 is filled with the inner resin 61 that is another part of the inner resin layer 13 at a predetermined pressure. Then, the third storage chamber 46 is filled with the outer resin 62 that becomes the outer resin layer 14 at a predetermined pressure. An optical fiber bare wire 1N is passed through the first housing chamber 44 so as to pass through the first die port 55H from above. The bare optical fiber 1N that has passed through the first accommodation chamber 44 is passed through the second accommodation chamber 45 so as to pass from the first die port 55H serving as an insertion port to the second die port 56H. The bare optical fiber 1N that has passed through the second housing chamber 45 is passed through the third housing chamber 46 so as to pass from the second die port 56H as the insertion port to the third die port 57H.

  In the manufacturing apparatus 100 of the present embodiment, the bare optical fiber 1N passes through the first storage chamber 44, the second storage chamber 45, and the third storage chamber 46 in this order, and the upper portion of the first storage chamber 44 is open. For this reason, as described above, even if the bare optical fiber 1N is shaken in the direction perpendicular to the longitudinal direction, the outer peripheral surface of the bare optical fiber 1N comes into contact with the first die body 43 and the bare optical fiber It is possible to suppress the outer peripheral surface of the wire 1N from being scratched, and to suppress the mechanical strength of the optical fiber 1 from being lowered. Further, in the manufacturing apparatus 100 of the present embodiment, the inner resin 61 in which the bare optical fiber 1N coated with the inner resin 61 that is a part of the inner resin layer 13 is the other part of the inner resin layer 13 is a predetermined amount. It passes through the second storage chamber 45 filled with pressure. Therefore, as described above, even if a deviation occurs in the thickness of the inner resin 61 that becomes a part of the inner resin layer 13 applied to the outer peripheral surface of the bare optical fiber 1N, the deviation is leveled. The inner resin 61 that is another part of the inner resin layer 13 can be applied, and the thickness of the inner resin layer 13 can be prevented from being biased. In addition, in the manufacturing apparatus 100 of the present embodiment, the bare optical fiber 1N coated with the inner resin 61 passes through the third housing chamber 46 filled with the outer resin 62 with a predetermined pressure. The occurrence of unevenness in the thickness of the outer resin layer 14 is suppressed. In this way, the manufacturing apparatus 100 of the present embodiment can suppress a decrease in mechanical strength of the optical fiber 1 while suppressing the occurrence of bias in the thickness of the resin coating layer 12.

  Moreover, since the manufacturing apparatus 100 of this embodiment is provided with the guide member 70, it can suppress that the thickness of the inner side resin 61 apply | coated to the outer peripheral surface of the optical fiber bare wire 1N arises as mentioned above.

  In addition, a slit 71 is formed on the side surface of the guide member 70 as a communication portion that communicates the outer region and the inner region of the guide member 70 in the inner resin 61. For this reason, compared with the case where the slit 71 is not formed on the side surface of the guide member 70, the inner resin 61 positioned in the outer region of the guide member 70 can be easily flown into the inner region of the guide member 70, The convection Cf in the inner resin 61 stored in the first storage chamber 44 can be further stabilized. For this reason, it can suppress more that a bias arises in the thickness of the inner side resin 61 apply | coated to the outer peripheral surface of the optical fiber bare wire 1N.

  In the manufacturing apparatus 100 of the present embodiment, the first die port 55H of the first storage chamber 44 also serves as the first insertion port for inserting the bare optical fiber 1N into the second storage chamber 45. The main body 43 can be downsized. In the manufacturing apparatus 100 of the present embodiment, as described above, the inner optical resin 61 that becomes a part of the inner resin layer 13 is applied to the bare optical fiber 1N through the first die port 55H and the second optical fiber 1N is applied. It is inserted into the storage chamber 45. For this reason, even if the bare optical fiber 1N is shaken in the direction perpendicular to the longitudinal direction, the first die port 55H of the first storage chamber 44 does not serve as the first insertion port of the second storage chamber 45. As compared with the above, it is possible to suppress the inner resin 61 applied to the bare optical fiber 1N from coming into contact with the edge of the first insertion port of the second storage chamber 45. Therefore, compared with the case where the first die port 55H does not also serve as the insertion port of the second storage chamber 45, even if the bare optical fiber 1N is shaken in the direction perpendicular to the longitudinal direction, the bare optical fiber It is possible to further suppress the occurrence of unevenness in the thickness of the inner resin 61 applied to 1N.

  Further, in the manufacturing apparatus 100 of the present embodiment, the second die port 56H of the second storage chamber 45 also serves as the second insertion port for inserting the bare optical fiber 1N into the third storage chamber 46. The main body 43 can be downsized. In the manufacturing apparatus 100 of the present embodiment, as described above, the inner side resin 61 that is another part of the inner side resin layer 13 is applied to the bare optical fiber 1N through the second die port 56H. It is inserted into the third storage chamber 46. For this reason, even if the optical fiber bare wire 1N is shaken in the direction perpendicular to the longitudinal direction, the second die port 56H of the second storage chamber 45 may not serve as the second insertion port of the third storage chamber 46. As compared with the above, the inner resin 61 applied to the bare optical fiber 1N can be prevented from coming into contact with the edge of the second insertion port of the third storage chamber 46. For this reason, even if the optical fiber bare wire 1N is shaken in the direction perpendicular to the longitudinal direction compared to the case where the second die port 56H does not also serve as the insertion port of the third housing chamber 46, the bare optical fiber It is possible to further suppress the occurrence of unevenness in the thickness of the inner resin 61 applied to 1N.

  As mentioned above, although this invention was demonstrated to the example for embodiment, this invention is not limited to these.

  For example, the above embodiment has been described by taking the optical fiber 1 as an amplification optical fiber having a double clad structure as an example. However, the optical fiber includes a core, a clad surrounding the outer peripheral surface of the core, and an inner resin layer covering the outer peripheral surface of the clad and a resin coating layer including an outer resin layer covering the outer peripheral surface of the inner resin layer. As long as it is not particularly limited. For example, the optical fiber may be an optical fiber in which an active element excited by pumping light is not added to the core, may be an optical fiber having a single cladding structure in which the inner resin layer 13 is not an outer cladding, and a plurality of optical fibers may be used. A multi-core fiber having a core may be used. Further, the resin coating layer 12 of the above embodiment has the resin protective layer 15 that covers the outer peripheral surface of the outer resin layer 14. However, the resin coating layer 12 only needs to have at least the inner resin layer 13 and the outer resin layer 14, and the resin coating layer 12 may not have the resin protective layer 15, and is more than the resin protective layer 15. You may have another resin layer on the outer side. For example, when the resin coating layer 12 does not have the resin protective layer 15, the optical fiber manufacturing method does not include the fourth resin coating step P8 and the second curing step P9, and the configuration of the coating unit 41 is the second coating unit. It is set as the structure which does not have 41S, and the structure of the hardening part 42 is set as the structure which does not have the 2nd hardening part 42S.

  Moreover, in the said embodiment, the external shape of the bare optical fiber 1N in the cross section perpendicular | vertical to a longitudinal direction was noncircular, and was made into the regular heptagon. However, the external shape of the bare optical fiber 1N in the cross section perpendicular to the longitudinal direction is not particularly limited, and is a polygon such as a hexagon, a heptagon, an octagon, or a shape with rounded corners. These may be non-circular or circular.

  In the drawing process P2 of the above embodiment, the lower end portion of the optical fiber preform 1P is moved in the heating furnace 25 while rotating the optical fiber preform 1P around the central axis Pa of the optical fiber preform 1P. The drawing process was performed while heating. However, the drawing process P2 may be a process of drawing the lower end portion of the optical fiber preform 1P while heating it in the heating furnace 25 without rotating the optical fiber preform 1P. When the drawing process P2 is such a process, an optical fiber in which no permanent twist is imparted to the bare optical fiber 1N can be manufactured.

  Moreover, in the said embodiment, the 1st application | coating part 41F provided with the 1st die main body 43 in which the 1st storage chamber 44, the 2nd storage chamber 45, and the 3rd storage chamber 46 are formed, and the guide member 70 is demonstrated to an example. did. However, the first application unit 41F may not include the guide member 70. However, from the viewpoint of suppressing the occurrence of unevenness in the thickness of the inner resin layer 13, the first application part 41 </ b> F preferably includes the guide member 70.

  Moreover, in the said embodiment, the cylindrical guide member 70 in which the three slits 71 extended upward from a lower end were demonstrated was demonstrated to the example. However, the guide member is a cylindrical member that is separated from the outer peripheral surface of the bare optical fiber 1N and surrounds the bare optical fiber 1N in at least the inner resin 61 stored in the first storage chamber 44, and There is no particular limitation as long as the inner resin 61 can flow into the inner region of the guide member. In addition, the communication portion formed on the side surface of the guide member 70 is not particularly limited as long as the outer region of the guide member 70 and the inner region in the inner resin 61 communicate with each other. For example, the slit 71 formed on the side surface of the guide member 70 may be a slit extending downward from the upper end. In this case, the guide member 70 is disposed so that at least a part of the slit 71 is positioned in the inner resin 61 stored in the first storage chamber 44. Further, the three slits 71 do not have to be positioned at substantially equal intervals in the circumferential direction of the guide member 70. However, from the viewpoint of stabilizing the convection Cf in the inner resin 61, it is preferable that the three slits 71 are located at substantially equal intervals in the circumferential direction of the guide member 70. The number of slits 71 is not particularly limited, and may be one or two, or four or more. Further, on the side surface of the guide member 70, instead of the slit 71, a through hole as a communication portion penetrating from the outer peripheral surface to the inner peripheral surface may be formed, and the through hole and the slit 71 are formed as the communication portion. May be. When the communication portion is formed on the side surface of the guide member 70, the upper end of the guide member 70 is located above the liquid level of the inner resin 61 and the lower end of the guide member 70 is the bottom wall portion of the first block 51. It may be in contact with 51b. Even in such a guide member 70, the inner resin 61 flows from the communicating portion of the guide member 70 into the inner region of the guide member 70.

  Further, the guide member 70 may be a member as shown in FIG. FIG. 7 is a view showing a guide member according to a modified example, FIG. 7A is a perspective view of the guide member 70 according to the modified example, and FIG. 7B is a guide member 70 according to another modified example. FIG. 7C is a view showing a state in which the guide member 70 according to still another modified example is arranged in the first storage chamber 44.

  A guide member 70 shown in FIG. 7A is a cylindrical member having an outer diameter and an inner diameter reduced from the upper side to the lower side, and the side surface of the guide member 70 serves as a communicating portion in the vertical direction from the upper end to the lower end. One slit 71 extending in the direction is formed. The inner diameter at the lower end that is the minimum inner diameter of the guide member 70 is larger than the outer diameter of the bare optical fiber 1N. Even in such a guide member 70, the convection Cf is stabilized by narrowing the region where the convection Cf occurs in the inner resin 61 and reducing the concave meniscus Me in the same manner as the guide member 70 of the above embodiment. obtain. If the width of the slit 71 is larger than the outer shape of the bare optical fiber 1N, the guide member 70 can be removed even when the bare optical fiber 1N passes through the first housing chamber 44. It can be attached. For this reason, the guide member 70 can be removed or attached without interrupting the drawing of the optical fiber preform 1P.

  A guide member 70 shown in FIG. 7B is a rectangular cylindrical member extending in the vertical direction, and one slit 71 extending in the vertical direction from the upper end to the lower end is formed as a communicating portion on the side surface of the guide member 70. Has been. In the cross section perpendicular to the extending direction of the guide member 70, the diameter of the circle in contact with the inner peripheral surface of the guide member 70 is larger than the outer diameter of the bare optical fiber 1N. Even in such a guide member 70, the convection Cf is stabilized by narrowing the region where the convection Cf occurs in the inner resin 61 and reducing the concave meniscus Me in the same manner as the guide member 70 of the above embodiment. obtain. When the width of the slit 71 is larger than the outer shape of the bare optical fiber 1N, the drawing of the optical fiber preform 1P is interrupted in the same manner as the guide member 70 shown in FIG. Without this, the guide member 70 can be removed or attached. However, from the viewpoint of stabilizing the convection Cf in the inner resin 61, in a cross section perpendicular to the extending direction of the guide member 70, such as the guide member 70 of the above embodiment and the guide member 70 shown in FIG. The shape of the inner periphery of the guide member 70 is preferably a circle.

  The guide member 70 shown in FIG. 7C is different from the guide member 70 in the above embodiment in that the slit 71 is not formed and the length in the vertical direction is short. In FIG. 7C, the description of the second block 52 and the third block 53 of the first die body 43 and the second die body 54 is omitted for easy understanding. Such a guide member 70 is located, for example, entirely in the inner resin 61 stored in the first storage chamber 44, and the lower end of the guide member 70 is separated from the bottom wall portion 51 b of the first block 51. It arrange | positions so that the optical fiber bare wire 1N may pass through the area | region. In the guide member 70 arranged in this way, the inner resin 61 can flow into the region inside the guide member 70 from the opening at the upper end and the opening at the lower end of the guide member 70. Even in such a guide member 70, the convection Cf is stabilized by narrowing the region where the convection Cf occurs in the inner resin 61 and reducing the concave meniscus Me in the same manner as the guide member 70 of the above embodiment. obtain. 7C, when the lower end of the guide member 70 is separated from the bottom wall portion 51b of the first block 51, the upper end of the guide member 70 is located above the liquid level of the inner resin 61. You may do it. When the upper end of the guide member 70 is located below the liquid level of the inner resin 61, the lower end of the guide member 70 may be in contact with the bottom wall portion 51 b of the first block 51. Even in such a guide member 70, the inner resin 61 flows into the region inside the guide member 70 from the opening at the upper end and the opening at the lower end of the guide member 70.

  Further, in the above embodiment, the first die port 55H of the first storage chamber 44 also serves as the first insertion port for inserting the bare optical fiber 1N into the second storage chamber 45, and the second of the second storage chamber 45. The die port 56 </ b> H also served as a second insertion port for inserting the bare optical fiber 1 </ b> N into the third housing chamber 46. However, the first die port 55H may not serve as the first insertion port for inserting the bare optical fiber 1N into the second housing chamber 45, and the second die port 56H is bare to the third housing chamber 46. The second insertion port for inserting the line 1N may not be used. For example, the second block 52 is separated from the first block 51 as the first die body 43 in which the first die port 55H also serves as the first insertion port for inserting the bare optical fiber 1N into the second housing chamber 45. A configuration in which a nipple for inserting the bare optical fiber 1N into the top wall portion 52t is attached so that the inner resin 61 can be filled in the second storage chamber 45 with a predetermined pressure. Further, as the first die body 43 in which the second die port 56H also serves as the second insertion port for inserting the bare optical fiber 1N into the third housing chamber 46, for example, the third block 53 is changed from the first block 51. The structure which attaches the nipple for inserting the optical fiber bare wire 1N in the spaced apart top wall part 53t, and can fill the 3rd storage chamber 46 with the outer side resin 62 with predetermined | prescribed pressure is mentioned. The nipple here is a cylindrical member similar to the nipple 59 attached to the second die body 54. The second block 52 and the third block 53 may be connected to each other while the first block 51 and the second block 52 are separated from each other. Further, the first block 51 and the second block 52 may be connected to each other while the second block 52 and the third block 53 are separated from each other.

  In the above-described embodiment, the uncured inner resin 61 and the outer resin 62 applied to the bare optical fiber 1N by the first curing portion 42F are cured, and applied to the bare optical fiber 1N by the second curing portion 42S. The uncured protective resin 63 thus cured was cured. However, the curing part 42 is not particularly limited as long as the uncured resin applied to the bare optical fiber 1N is cured. For example, these uncured resins 61, 62, and 63 may be cured by one cured portion. For example, the curing unit may be disposed below the second application unit 41S and cure the uncured inner resin 61, outer resin 62, and protective resin 63 applied to the bare optical fiber 1N. good. In this case, the fourth housing chamber is filled with the uncured protective resin 63 serving as the resin protective layer 15 with a predetermined pressure in the bare optical fiber 1N coated with the uncured inner resin 61 and the outer resin 62. 47 is inserted from the third insertion port 59H and extracted from the fourth die port 58H. Then, a protective resin 63 is applied to the outer peripheral surface of the bare optical fiber 1N to which the inner resin 61 and the outer resin 62 are applied. The curing unit cures the uncured inner resin 61, outer resin 62, and protective resin 63 applied to the bare optical fiber 1N in this way. In such a case, the third die port 57H of the third storage chamber 46 may also serve as the third insertion port 59H of the nipple 59 of the second main body, and the first die main body 43 and the second die main body 54 are mutually connected. Will be linked.

  Moreover, in the said embodiment, the optical fiber 1N was formed by the drawing process P2, and the optical fiber 1 was manufactured by forming the resin coating layer 12 in this optical fiber bare wire 1N. However, the optical fiber manufacturing method may not include the drawing step P2. In this case, for example, the bare optical fiber 1N is prepared in the preparation step P1, and the optical fiber 1 is formed by forming the resin coating layer 12 on the bare optical fiber 1N by passing the bare optical fiber 1N through the coating layer forming apparatus 40. May be manufactured.

  Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1
FIG. 8 is a diagram showing the coating section used in Example 1 as in FIG. 3, and FIG. 9 is a diagram showing the optical fiber manufactured in Example 1 as in FIG. 8, components having the same configuration as in FIG. 3 are denoted by the same reference numerals, and in FIG. 9, components having the same configuration as in FIG. The application unit 41 used in Example 1 is different from the application unit 41 illustrated in the above embodiment in that the application unit 41 does not include the second application unit 41S and includes the first application unit 41F. Using the manufacturing apparatus 100 provided with the coating layer forming apparatus 40 having such a coating part 41, as shown in FIG. 9, the point that the outer shape of the bare optical fiber 1N in a cross section perpendicular to the longitudinal direction is circular and the resin The optical fiber 1 different from the optical fiber 1 illustrated in the above embodiment in that the coating layer 12 does not have the resin protective layer 15 was manufactured. Similar to the optical fiber 1 illustrated in the above embodiment, the optical fiber 1 is an amplification optical fiber having a double clad structure in which the clad 11 is an inner clad and the inner resin layer 13 is an outer clad. Specifically, the optical fiber preform 1P having a circular outer shape in a cross section in the direction perpendicular to the longitudinal direction is rotated at 250 rpm around the central axis Pa of the optical fiber preform 1P at 15 m / min. Drawing was performed at a drawing speed of. By this drawing, an optical fiber bare wire 1N having an outer diameter of 250 μm was formed, and this optical fiber bare wire 1N was passed through the coating layer forming apparatus 40, whereby the optical fiber 1 shown in FIG. 9 was manufactured. In this example, 10 lots of the optical fiber 1 having a length of 5 km were manufactured. The pressure of the inner resin 61 filled in the second storage chamber 45 of the coating layer forming apparatus 40 is 0.10 MPa, the pressure of the outer resin 62 charged in the third storage chamber 46 is 0.05 MPa, and the first A stable meniscus Me was formed in the inner resin 61 stored in the storage chamber 44.

(Comparative Example 1)
FIG. 10 is a view showing the application section used in Comparative Example 1 in the same manner as FIG. 8, and in FIG. 10, components having the same configuration as in FIG. The application part 41 used in Comparative Example 1 is different from the application part 41 used mainly in Example 1 above in that the first storage chamber 44 is not formed in the first die body 43. In the second block 52 of the first die main body 43 in Comparative Example 1, the first die 55 is attached to the top wall portion 52t. The first die 55 is fitted into a circular through hole formed in the top wall portion 52t so that the central axis substantially coincides with the central axis of the second die 56, and is fixed to the top wall portion 52t. Such an internal space of the second block 52 serves as the second storage chamber 45.

  Ten lots of the optical fiber 1 having a length of 5 km were manufactured in the same manner as in Example 1 except that the coating part 41 was changed to the coating part 41 shown in FIG.

(Comparative Example 2)
FIG. 11 is a view showing the application part used in Comparative Example 2 in the same manner as in FIG. 8. In FIG. 11, components having the same configuration as in FIG. The application unit 41 used in Comparative Example 2 is different from the application unit 41 used mainly in Example 1 above in that the second storage chamber 45 is not formed in the first die body 43 and the guide member 70 is not arranged. In the third block 53 of the first die main body 43 in this comparative example, the side wall 53s is separated from the outer peripheral surface of the side wall 51s of the first block 51 and surrounds the side wall 51s, and the bottom wall 53b is the first block 51. The opening on the lower side of the side wall portion 53s is closed away from the lower surface of the bottom wall portion 51b, and the top wall portion 53t extends from the entire periphery of the upper end portion of the side wall portion 53s to the side wall portion 51s side of the first block 51. And connected to the side wall 51s. Such an internal space of the third block 53 serves as the third storage chamber 46. Further, the diameter of the first die port 55H in the first block 51 is substantially the same as the diameter of the second die port 56H shown in FIG.

  Ten lots of the optical fiber 1 having a length of 5 km were manufactured in the same manner as in Example 1 except that the coating part 41 was changed to the coating part 41 shown in FIG.

(Proof survival)
Each optical fiber 1 manufactured in this way was rewound while performing a bending test. FIG. 12 is a diagram illustrating a part of the bending test of the optical fiber. In this bending test, the optical fiber 1 is wound around a plurality of pulleys 90 so that the optical fiber 1 is sequentially wound in different directions. FIG. 12 shows an arrow indicating the winding direction. The directions in which the optical fiber 1 is bent are eight radial directions in a cross section perpendicular to the longitudinal direction, and the two adjacent directions are directions shifted by approximately 45 degrees in the circumferential direction. The radius of curvature in bending of the optical fiber 1 was set such that stress applied to the bare optical fiber 1N was applied to the outer peripheral surface of the optical fiber 1 when the bare optical fiber 1N was stretched by 1%. A value obtained by dividing the total length of the optical fiber subjected to the bending test by the number of times the optical fiber was broken during the bending test was calculated as the proof survival length. The proof survival length of the optical fiber 1 of Example 1 is 10 km / time, the proof survival length of the optical fiber 1 of Comparative Example 1 is 0.2 km / time, and the proof survival length of the optical fiber 1 of Comparative Example 2 is It was 10 km / time. The proof lifetime of the optical fiber 1 of Comparative Example 1 is shorter than the proof lifetime of the optical fiber 1 of Example 1 and Comparative Example 2, and the optical fiber 1 of Comparative Example 1 is the optical fiber of Example 1 and Comparative Example 2. The mechanical strength was lower than 1. This is because, in the manufacture of the optical fiber of Comparative Example 1, the optical fiber bare wire 1N is shaken due to the rotation of the optical fiber preform 1P, and the optical fiber bare wire is formed in the first die 55 of the second storage chamber 45. It can be considered that the outer peripheral surface of 1N is in contact and the outer peripheral surface of the bare optical fiber 1N is damaged.

(Light leakage)
For each optical fiber 1 manufactured in this way, it is confirmed whether or not light leakage occurs from the outer peripheral surface of the optical fiber 1 when visible light is incident on the cladding 11 that is the inner cladding from one end of the optical fiber 1. did. The optical fiber 1 of Example 1 and Comparative Example 1 had no light leakage, and the optical fiber 1 of Comparative Example 2 had light leakage. When a portion where light leakage occurred in the optical fiber 1 of Comparative Example 2 was observed, there was a portion where the inner resin layer 13 was hardly formed. This can be considered because the thickness of the inner resin layer 13 is biased in the manufacture of the optical fiber 1 of Comparative Example 2. On the other hand, in the manufacture of the optical fiber 1 of Example 1 and Comparative Example 1, it can be considered that deviations in the thickness of the inner resin layer 13 and the outer resin layer 14 are suppressed.

  As described above, according to the manufacturing method of the present invention, the resin coating layer 12 is formed by suppressing occurrence of bias in the thickness of each resin layer in the resin coating layer 12 having the inner resin layer 13 and the outer resin layer 14. At this time, it was confirmed that the optical fiber 1 capable of suppressing the decrease in the mechanical strength of the optical fiber 1 can be manufactured even if the bare optical fiber 1N is shaken.

  As described above, according to the present invention, an optical fiber manufacturing method and an optical fiber that can suppress the mechanical strength of the optical fiber from decreasing while suppressing the occurrence of bias in the thickness of the resin coating layer. A manufacturing apparatus is provided and is expected to be used in fields such as optical fiber communication and amplification optical fiber.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber 1N ... Optical fiber bare wire 1P ... Optical fiber preform 10 ... Core 11 ... Cladding 12 ... Resin coating layer 13 ... Inner resin layer 14 ... Outer resin layer 15 ... resin protective layer 41 ... application part 41F ... first application part 41S ... second application part 43 ... first die body 44 ... first storage chamber 45 2nd storage chamber 46 ... 3rd storage chamber 47 ... 4th storage chamber 54 ... 2nd die main body 55H ... 1st die port 56H ... 2nd die port 57H ... Third die port 58H ... Fourth die port 59H ... Third insertion port 61 ... Inner resin 62 ... Outer resin 63 ... Protective resin 70 ... Guide member 71 ... Slit P2 ... Drawing step P4 ... First resin application step P5 ... Second resin application step P6 ... Third resin Cloth step P8 · · · fourth resin coating step Cf · · · convection Me · · · meniscus

Claims (16)

An optical fiber comprising: a core; a clad surrounding the outer peripheral surface of the core; an inner resin layer covering the outer peripheral surface of the clad; and a resin coating layer including an outer resin layer covering the outer peripheral surface of the inner resin layer. A manufacturing method comprising:
Light having the core and the clad from above the first storage chamber in the first storage chamber in which the upper side is open and the first die port is formed in the lower side and the inner resin that is a part of the inner resin layer is stored. A first resin coating step in which a bare fiber is inserted and extracted from the first die port, and the inner resin serving as a part of the inner resin layer is applied to an outer peripheral surface of the bare optical fiber;
The inner resin layer is provided in a second storage chamber having a first insertion port on the upper side and a second die port on the lower side and filled with the inner resin as another part of the inner resin layer with a predetermined pressure. The optical fiber bare wire coated with the inner resin to be a part of the inner resin layer is inserted from the first insertion port and is extracted from the second die port, and the inner resin to be a part of the inner resin layer is coated. A second resin application step of applying the inner resin to be another part of the inner resin layer on the outer peripheral surface of the bare optical fiber;
A third housing chamber having a second insertion port on the upper side and a third die port on the lower side and filled with an outer resin serving as the outer resin layer at a predetermined pressure, and another part of the inner resin layer, The optical fiber bare wire coated with the inner resin is inserted from the second insertion port and extracted from the third die port, and the inner resin that is another part of the inner resin layer is coated. A third resin application step of applying the outer resin to the outer peripheral surface of the bare optical fiber;
Equipped with a,
A guide member that is spaced apart from the outer peripheral surface of the bare optical fiber in the inner resin accommodated in at least the first containing chamber and that surrounds the bare optical fiber is disposed;
The guide member can flow the inner resin into a region inside the guide member,
The guide member is formed with one slit extending in the vertical direction from the upper end to the lower end and having a width in a direction perpendicular to the vertical direction larger than the outer diameter of the bare optical fiber. An optical fiber manufacturing method characterized by the above. The method of manufacturing an optical fiber according to claim 1, wherein an outer diameter and an inner diameter of the guide member are reduced from the upper side to the lower side . The method for manufacturing an optical fiber according to claim 1 or 2, wherein the entire guide member is located in the inner resin accommodated in the first accommodation chamber . The method of manufacturing an optical fiber according to any one of claims 1 3, characterized by arranging the guide member prior to storing the inner resin to the first storage chamber. 5. The method of manufacturing an optical fiber according to claim 1, wherein the resin constituting the inner resin layer is a resin having a refractive index lower than that of the clad. 6. The method according to claim 1, further comprising a drawing step of forming the bare optical fiber by drawing the optical fiber preform while rotating the optical fiber preform around the central axis of the optical fiber preform. The manufacturing method of the optical fiber of Claim 1. 7. The pressure according to claim 1, wherein a pressure of the outer resin filled in the third storage chamber is smaller than a pressure of the inner resin filled in the second storage chamber. The manufacturing method of the optical fiber of description. The optical fiber manufacturing method according to any one of claims 1 to 7, wherein the first die port of the first storage chamber also serves as the first insertion port of the second storage chamber. 9. The method of manufacturing an optical fiber according to claim 1, wherein the second die port of the second storage chamber also serves as the second insertion port of the third storage chamber. The bare optical fiber coated with the outer resin is inserted into a fourth housing chamber having a third insertion port on the upper side and a fourth die port on the lower side and filled with a predetermined resin at a predetermined pressure. Further comprising a fourth resin application step of applying the predetermined resin to an outer peripheral surface of the bare optical fiber coated with the outer resin, inserted from the third insertion port and extracted from the fourth die port ;
The first storage chamber, the second storage chamber, and the third storage chamber are formed in a first die body,
The method of manufacturing an optical fiber according to any one of claims 1 to 9, wherein the fourth housing chamber is formed in a second die body that is separated from the first die body. . An optical fiber comprising: a core; a clad surrounding the outer peripheral surface of the core; an inner resin layer covering the outer peripheral surface of the clad; and a resin coating layer including an outer resin layer covering the outer peripheral surface of the inner resin layer. Manufacturing equipment,
A first storage chamber in which the upper part is opened and the lower part has a first die opening and an inner resin that is a part of the inner resin layer is stored, and a second insertion part is provided in the lower part and has a first insertion opening. A second storage chamber in which the inner resin, which is another part of the inner resin layer, is filled with a predetermined pressure, a second insertion port on the upper side, a third die port on the lower side, and the outer side A first die body including a third storage chamber filled with an outer resin serving as a resin layer at a predetermined pressure ;
A guide member;
With
In the first housing chamber, an optical fiber bare wire having the core and the clad is passed through from above to the first die port,
Through the second storage chamber, the bare optical fiber that has passed through the first storage chamber passes through the first insertion port to the second die port,
Through the third storage chamber, the bare optical fiber that has passed through the second storage chamber is passed through the second insertion port to the third die port ,
The guide member surrounds the bare optical fiber at a distance from the outer peripheral surface of the bare optical fiber in at least the inner resin stored in the first storage chamber, and the guide member has a region inside the guide member. The inner resin can flow in,
The guide member is formed with one slit extending in the vertical direction from the upper end to the lower end and having a width in a direction perpendicular to the vertical direction larger than the outer diameter of the bare optical fiber. An optical fiber manufacturing apparatus characterized by the above. The optical fiber manufacturing apparatus according to claim 11, wherein the outer diameter and the inner diameter of the guide member are reduced from the upper side to the lower side . The optical fiber manufacturing apparatus according to claim 11 or 12 , wherein the entire guide member is located in the inner resin accommodated in the first accommodation chamber . The optical fiber manufacturing apparatus according to any one of claims 11 to 13, wherein the first die port of the first storage chamber also serves as the first insertion port of the second storage chamber. The optical fiber manufacturing apparatus according to claim 11, wherein the second die port of the second storage chamber also serves as the second insertion port of the third storage chamber.   A second die body including a fourth storage chamber having a third insertion port on the upper side and a fourth die port on the lower side and filled with a predetermined resin at a predetermined pressure;
  The optical fiber bare wire that has passed through the third storage chamber is passed through the fourth storage chamber so as to come out from the third insertion port to the fourth die port,
  The second die body is separated from the first die body.
The optical fiber manufacturing apparatus according to any one of claims 11 to 15, wherein

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