CN113121104B - Optical fiber preform and method for preparing optical fiber preform and optical fiber - Google Patents
Optical fiber preform and method for preparing optical fiber preform and optical fiber Download PDFInfo
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- CN113121104B CN113121104B CN201911421838.7A CN201911421838A CN113121104B CN 113121104 B CN113121104 B CN 113121104B CN 201911421838 A CN201911421838 A CN 201911421838A CN 113121104 B CN113121104 B CN 113121104B
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
- C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
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Abstract
The invention provides an optical fiber preform and a method for preparing the optical fiber preform and an optical fiber, wherein light-transmitting sheets with different refractive indexes are inserted into a sleeve in a staggered way, gaps in the sleeve are filled by a capillary rod, the prepared sleeve is subjected to optical fiber drawing to obtain the optical fiber, wherein the light-transmitting sheets are taken as fiber cores, and the sleeve is taken as a cladding.
Description
Technical Field
The invention belongs to the field of optical fiber preparation, and in particular relates to an optical fiber preform and a method for preparing the optical fiber preform and an optical fiber.
Background
The transmission performance of the optical fiber is determined by the structure of the optical fiber, and the reasonable refractive index distribution can meet the requirements of different types of optical fibers. Most of the existing optical fiber preforms are manufactured by an in-tube chemical vapor deposition method such as MCVD, PCVD, FCVD and an outside deposition method such as OVD and VAD, but in the above method, in order to ensure uniformity of preform materials during chemical vapor deposition, both the tube and the rod are in a uniform rotation process during deposition, so that the preform is circular, and the light-conducting core region is also circular. The preform is then drawn into an optical fiber.
The fiber core of the fiber prepared by the method is generally circular, has good circular symmetry structure, but in specific certain application occasions, the fiber core is not the circular symmetry structure with the refractive index, such as panda-type polarization maintaining fiber, which is a typical stress birefringence fiber, wherein the birefringence is generated by thermal stress in the material and mechanical stress outside the material, and the material is subjected to stress to cause the change of the refractive index of the material, namely, the elastic light effect to generate birefringence. The panda type polarization-maintaining optical fiber fast and slow axes are formed by punching a prefabricated rod and inserting a stress rod with a very high thermal expansion coefficient in the air, and the process is complex in process and high in equipment requirement.
Chinese patent CN103246010B 'an optical fiber with multiple refractive indexes' is characterized in that the optical fiber with different refractive indexes is obtained by sequentially wrapping a fiber core, an inner cladding and an outer cladding from inside to outside, but the refractive indexes of the optical fiber still belong to a circularly symmetrical structure, and the optical fiber is not suitable for preparing a polarization maintaining optical fiber. Chinese patent CN104591534B, a manufacturing method of polarization-maintaining optical fiber, symmetrically cuts a notch on the central line of the inner cavity of the first layer sleeve, fills a stress rod at the notch, embeds an optical fiber preform core rod in the first layer sleeve, embeds a second layer sleeve outside the first layer sleeve to form a polarization-maintaining optical fiber preform, and wire-drawing the polarization-maintaining optical fiber preform into Cheng Bao polarizing optical fiber, but the technology is complex in manufacturing and high in preparation cost, and the polarization-maintaining optical fiber preforms with different refractive indexes cannot be combined at will according to the requirement to obtain the required optical fiber.
Disclosure of Invention
The invention aims to solve the technical problems of complex preparation process of optical fibers with different refractive indexes by providing an optical fiber preform and a method for preparing the optical fiber preform and the optical fiber.
In order to solve the technical problems, the invention adopts the following technical scheme: the optical fiber preform comprises a sleeve, wherein the sleeve is of a hollow structure, a light-transmitting sheet is filled in the sleeve, and a capillary rod is filled between the light-transmitting sheet and the sleeve.
In a preferred embodiment, the light-transmitting sheet is provided with one sheet.
In a preferred embodiment, the light-transmitting sheet is provided with a plurality of sheets.
In the preferred scheme, the light-transmitting sheet is provided with a plurality of light-transmitting sheets, and the plurality of light-transmitting sheets comprise first light-transmitting sheets and second light-transmitting sheets which are arranged in a staggered mode, wherein the thicknesses of the first light-transmitting sheets and the second light-transmitting sheets are the same, and the refractive indexes of the first light-transmitting sheets and the second light-transmitting sheets are different.
In the preferred scheme, the light-transmitting sheet is provided with a plurality of light-transmitting sheets, and the plurality of light-transmitting sheets comprise first light-transmitting sheets and second light-transmitting sheets which are arranged in a staggered mode, wherein the thicknesses of the first light-transmitting sheets and the second light-transmitting sheets are different, and the refractive indexes of the first light-transmitting sheets and the second light-transmitting sheets are the same.
In the preferred scheme, the light-transmitting sheet is provided with a plurality of light-transmitting sheets, the thickness of the light-transmitting sheets is the same, and the refractive indexes of the light-transmitting sheets are different.
In a preferred scheme, the light-transmitting sheets are provided with a plurality of light-transmitting sheets, the thickness of the light-transmitting sheets is different, and the refractive indexes of the light-transmitting sheets are the same.
In a preferred scheme, the light-transmitting sheets are provided with a plurality of light-transmitting sheets, and the light-transmitting sheets are different in thickness and refractive index.
A method for preparing an optical fiber preform and an optical fiber comprises the following steps:
s1, inserting a light-transmitting sheet into a sleeve;
S2, filling gaps in the sleeve by using a capillary rod;
s3, performing optical fiber drawing on the sleeve pipe prepared according to the step S2 to obtain the optical fiber.
In a preferred scheme, the specific implementation steps of the step S3 are as follows:
s31, connecting an extension tube to one side of the sleeve opposite to the tapered tube;
S32, erecting the sleeve, and downwards pulling the tapered end;
s33, installing a plug for wire drawing sealing on the sleeve extension pipe;
s34, erecting the prefabricated rod on a feeding mechanism of a wire drawing tower, enabling the prefabricated rod to enter a furnace, slowly heating, turning around the prefabricated rod, and then opening to vacuumize;
S35, performing yarn control on the optical fiber to prepare the optical fiber.
The invention provides an optical fiber preform and a method for preparing the same, which have the following beneficial effects by adopting the scheme:
1. The invention breaks the conventional circle center symmetrical structure, realizes the change of the refractive index along with the change of the incident light direction, and can realize the polarization maintaining fiber effect without the panda type polarization maintaining fiber manufacturing process with complex process. According to the invention, the optical fiber drawing is carried out by stacking the light-transmitting sheets with different refractive indexes, so that the optical fiber with different refractive indexes is obtained, the refractive index cannot be controlled by the polarization maintaining optical fiber prepared by adding the stress rod in the prior art, but the arrangement and distribution of the light-transmitting sheets with different refractive indexes can be freely combined according to the requirement, and the optical fiber with different refractive indexes can be prepared according to the requirement.
2. The preparation cost of the optical fibers with different refractive indexes is reduced, the preparation process of the optical fibers with different refractive indexes is simplified, the optical fibers with different refractive indexes can be obtained without using a stress rod, and the preparation cost is greatly reduced.
3. The invention has wider material selection, the common adopted MCVD, PCVD, FCVD equipment in the optical fiber industry is only suitable for quartz glass, the doping materials for adjusting the refractive index are limited, and the doping materials are generally germanium, fluorine, phosphorus and other elements.
4. The thickness of the glass sheet is flexibly adjusted, the process of the glass sheet is mature, the size, the thickness and the refractive index uniformity are controllable, the thinner glass sheets can be arranged, the gradient refractive index gradual change effect is formed, and the effect similar to that of multimode optical fibers can be realized. The thinner the glass sheet is, the higher the smoothness of the gradual change of the refractive index is, and the polarization maintaining optical fibers with different refractive indexes are obtained by adjusting the thickness of the glass sheet, so that the technology which cannot be achieved by conventional chemical vapor deposition technologies such as pcvd, mcvd and the like is realized.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
FIG. 1 is a schematic illustration of a stack of light transmitting sheets and capillary rods in accordance with the present invention;
FIG. 2 is a schematic view of a dual-sleeve light transmitting sheet and capillary rod stack according to the present invention;
FIG. 3 is a schematic diagram of an end face of an optical fiber prepared in the present invention;
FIG. 4 is a schematic diagram of an end face of a panda-type polarization maintaining fiber according to the present invention;
FIG. 5 is a graph showing the refractive index profile of the fast axis of the panda-type polarization maintaining fiber according to the present invention;
FIG. 6 is a graph showing the refractive index profile of the slow axis of the panda-type polarization maintaining optical fiber according to the present invention;
FIG. 7 is a graph showing the refractive index profile of light incident into an optical fiber from a direction parallel to the glass sheet in accordance with the present invention;
FIG. 8 is a graph of the refractive index profile of light incident into an optical fiber from perpendicular to the glass sheet in accordance with the present invention;
FIG. 9 is a schematic diagram of an embodiment of the present invention;
FIG. 10 is a schematic diagram of a second embodiment of the present invention;
FIG. 11 is a schematic diagram of a third embodiment of the present invention;
in the figure: a sleeve 1; a light transmitting sheet 2; a first light-transmitting sheet 2-1; 2-2 parts of a second light-transmitting sheet; and a capillary rod 3.
Detailed Description
In the process of preparing the optical fiber, different types of optical fibers or optical fibers with different refractive indexes are obtained by adjusting the number, thickness and refractive index of the light transmitting sheets in the sleeve according to requirements.
Example 1:
as shown in fig. 9, the present embodiment prepares a flat core optical fiber, a rectangular core optical fiber by adjusting the number and thickness of light transmitting sheets. Under the same size, only a single thicker light-transmitting sheet can realize the preparation of flat core optical fibers and rectangular core optical fibers. The present embodiment provides a preform for preparing a flat core optical fiber, a rectangular core optical fiber, and a preparation method.
An optical fiber preform for preparing a flat core optical fiber and a rectangular core optical fiber comprises a sleeve 1, wherein the sleeve 1 is of a hollow structure, a light-transmitting sheet 2 is filled in the sleeve 1, and a capillary rod 3 is filled between the light-transmitting sheet 2 and the sleeve 1. The light-transmitting sheet 2 is provided with one sheet.
A method for preparing a flat core optical fiber, a rectangular core optical fiber preform and an optical fiber comprises the following implementation steps:
S1, drawing one side of the sleeve into a short cone, cleaning and sufficiently drying the material, and inserting a single thicker light-transmitting sheet into the sleeve to form the optical fiber preform.
S2, filling gaps in the sleeve by using capillary rods, wherein the refractive index of the capillary is the same as that of the sleeve.
S3, carrying out optical fiber drawing on the sleeve prepared according to the S2 to obtain an optical fiber, connecting an extension tube on one side of the sleeve relative to the drawing cone, erecting the sleeve, leading the drawing cone end to be downward, installing a plug for sealing the drawing on the extension tube of the sleeve, erecting a prefabricated rod on a feeding mechanism of a drawing tower, feeding the prefabricated rod into a furnace, slowly heating, turning around the prefabricated rod, starting vacuumizing, and drawing the optical fiber to obtain a flat core optical fiber and a rectangular core optical fiber.
Example 2:
as shown in fig. 10, the present embodiment produces an optical fiber without refractive steps by increasing the number and thickness of the transmission sheets.
An optical fiber preform comprises a sleeve 1, wherein the sleeve 1 is of a hollow structure, a light-transmitting sheet 2 is filled in the sleeve 1, and a capillary rod 3 is filled between the light-transmitting sheet 2 and the sleeve 1. The light-transmitting sheets 2 are provided with a plurality of light-transmitting sheets 2, the thickness of the light-transmitting sheets 2 is different, and the refractive indexes are the same. The number of the light-transmitting sheets 2 is 50, and the thickness of the corresponding light-transmitting sheets 2 is thinner under the same fiber core.
With the same core size, the more light transmitting sheets are used, the thinner each light transmitting sheet will be, the smoother will be, and there will be no refractive index steps. Optical fibers prepared by MCVD devices commonly found in the optical fiber industry are difficult to achieve smooth curves.
A method for preparing an optical fiber preform without refractive steps and an optical fiber is realized by the following steps:
S1, drawing one side of a sleeve into a short cone, cleaning and sufficiently drying a material, and sequentially inserting 50 thinner light-transmitting sheets into the sleeve to form an optical fiber preform.
S2, filling gaps in the sleeve by using capillary rods, wherein the refractive index of the capillary is the same as that of the light-transmitting sheet.
S3, carrying out optical fiber drawing on the sleeve prepared according to the S2 to obtain an optical fiber, connecting an extension tube on one side of the sleeve relative to the drawing cone, erecting the sleeve, leading the drawing cone end to be downward, installing a plug for sealing the drawing on the extension tube of the sleeve, erecting a prefabricated rod on a feeding mechanism of a drawing tower, feeding the prefabricated rod into a furnace, slowly heating, opening vacuumizing after the prefabricated rod turns around, and drawing the optical fiber to obtain the optical fiber without a refraction step.
Example 3:
As shown in fig. 11, the present embodiment prepares a polarization maintaining optical fiber by adjusting the thickness and refractive index of a light transmitting sheet.
An optical fiber preform comprises a sleeve 1, wherein the sleeve 1 is of a hollow structure, a light-transmitting sheet 2 is filled in the sleeve 1, and a capillary rod 3 is filled between the light-transmitting sheet 2 and the sleeve 1. The light-transmitting sheets 2 are provided with a plurality of light-transmitting sheets 2, and the light-transmitting sheets 2 are different in thickness and refractive index.
A method for manufacturing a polarization maintaining optical fiber preform and an optical fiber comprises the following implementation steps:
S1, drawing one side of a sleeve into a short cone, cleaning and fully drying a material, and arranging a plurality of light-transmitting sheets in a sequence that the thickness gradually becomes smaller from the middle to the two ends and the refractive index gradually becomes smaller from the middle to the two ends to form the optical fiber preform.
S2, filling gaps in the sleeve by using capillary rods, wherein the refractive index of the capillary is the same as that of a light-transmitting sheet at a filling position.
S3, carrying out optical fiber drawing on the sleeve prepared according to the S2 to obtain an optical fiber, connecting an extension tube on one side of the sleeve relative to the drawing cone, erecting the sleeve, leading the drawing cone end to be downward, installing a plug for sealing the drawing on the extension tube of the sleeve, erecting a prefabricated rod on a feeding mechanism of a drawing tower, feeding the prefabricated rod into a furnace, slowly heating, turning around the prefabricated rod, starting vacuumizing, and drawing the optical fiber to obtain the polarization maintaining optical fiber.
Example 4:
In the embodiment, the polarization maintaining optical fiber with the same effect as panda polarization maintaining optical fiber is prepared by adjusting the refractive index of the light transmitting sheet.
As shown in fig. 1 and 3, an optical fiber preform comprises a sleeve 1, wherein the sleeve 1 has a hollow structure, a light-transmitting sheet 2 is filled in the sleeve 1, and a capillary rod 3 is filled between the light-transmitting sheet 2 and the sleeve 1. The light-transmitting sheet 2 is provided with a plurality of sheets. The plurality of light-transmitting sheets 2 comprise first light-transmitting sheets 2-1 and second light-transmitting sheets 2-2 which are arranged in a staggered mode, wherein the thicknesses of the first light-transmitting sheets 2-1 and the second light-transmitting sheets 2-2 are the same, and the refractive indexes are different.
A method for preparing an optical fiber preform and an optical fiber comprises the following steps:
S1, preparing 9 n1 glass sheets with a refractive index of 1.4695, wherein the thickness is 0.25mm, the length is 300mm, and 8 n2 glass sheets with a refractive index of 1.4575, the thickness is 0.25mm, and the length is 300mm; preparing capillary rods m with refractive indexes 1.4695 and 1.4575 and diameters of 0.2mm as filling materials for manufacturing the prefabricated rod, wherein the refractive indexes of the capillary rods correspond to the refractive indexes of the glass sheets n1 and n 2; preparing a quartz sleeve with D75 x 32 x 300, tapering one end of the sleeve to the end of the extension tube according to the conventional optical fiber preform manufacturing process, cleaning and fully drying the materials. The thickness of the glass sheet can be adjusted according to the optical fibers with different refractive indexes, and the thinner the glass sheet is, the smoother the gradual change is, and the refractive index step is avoided.
According to a capillary rod stacking method similar to the manufacturing of photonic crystal fibers in the fiber industry, sequentially inserting and assembling n 1、n2 glass sheets with different widths into a sleeve in a staggered manner in sequence in a clean environment. A higher refractive index glass sheet may be arranged in the middle region of the fiber cross section and lower refractive index glass sheets may be arranged at the ends to provide a geometric birefringent polarization maintaining fiber, which is difficult to achieve using conventional chemical vapor deposition processes such as pcvd, mcvd, etc. The material of the glass sheet is not only suitable for quartz glass, but also various glass materials such as Schottky glass, heavy metal oxide glass and the like, and is also suitable for light-transmitting polymer materials such as light-transmitting plastic materials.
S2, filling gaps in the sleeve by using capillary rods m, filling the gaps in the sleeve by using the capillary rods m with refractive indexes corresponding to n1 and n2, wherein n1 is filled with n1 glass sheets, n2 is filled with n2 glass sheets, and the capillary rods are made of glass materials corresponding to the glass sheets.
S3, carrying out optical fiber drawing on the sleeve prepared according to the S2 to obtain an optical fiber, drawing one side of the sleeve into a short cone, connecting an extension tube relative to one side of the drawing cone, erecting the sleeve, leading the end of the drawing cone to be downward, installing a plug for drawing and sealing on the extension tube of the sleeve, erecting a prefabricated rod on a feeding mechanism of a drawing tower, leading the prefabricated rod into a furnace, slowly heating to 2250 ℃, preserving heat, turning around, and opening vacuumizing after turning around so as to eliminate gas in the prefabricated rod. The fiber was subjected to filament control to prepare a small-diameter polarization-maintaining fiber having a cladding diameter of 80 μm and an outer coating diameter of 135. Mu.m.
Example 5:
in the embodiment, the polarization maintaining optical fiber with the same effect as panda polarization maintaining optical fiber is prepared by adjusting the refractive index of the light transmitting sheet. . In comparison with embodiment 4, this embodiment provides an inner sleeve for facilitating the assembly of the preform in steps S1 and S2.
As shown in fig. 1 and 3, an optical fiber preform comprises a sleeve 1, wherein the sleeve 1 has a hollow structure, a light-transmitting sheet 2 is filled in the sleeve 1, and a capillary rod 3 is filled between the light-transmitting sheet 2 and the sleeve 1. The light-transmitting sheet 2 is provided with a plurality of sheets. The plurality of light-transmitting sheets 2 comprise first light-transmitting sheets 2-1 and second light-transmitting sheets 2-2 which are arranged in a staggered mode, wherein the thicknesses of the first light-transmitting sheets 2-1 and the second light-transmitting sheets 2-2 are the same, and the refractive indexes are different.
A method for preparing an optical fiber preform and an optical fiber comprises the following steps:
S1, preparing 9 n1 glass sheets with a refractive index of 1.4695, wherein the thickness is 0.25mm, the length is 300mm, and 8 n2 glass sheets with a refractive index of 1.4575, the thickness is 0.25mm, and the length is 300mm; capillary rods m having refractive indexes 1.4695 and 1.4575 and a diameter of 0.2mm were prepared and used as a filler in the preform production, and the refractive indexes of the capillary rods corresponded to the refractive indexes of the glass sheets n1 and n 2.
Thin-walled inner jacket tube T1 of D9 x 2 x 300 is prepared, the refractive index of the inner jacket tube T1 is 1.4575, and a short taper is drawn at one end of the inner jacket tube T1, quartz jacket tube of D75 x 32 x 300 is prepared as outer jacket tube T2, the outer jacket tube T2 is prepared according to the core-to-cladding ratio of the optical fiber, and the dimensions of the fiber core and cladding can be flexibly designed by the dimensional change of the glass sheets, for example, the core-to-cladding ratio is 9:125 to 105:125, etc., the outer jacket tube T2 is tapered at one end to the extension tube according to the conventional optical fiber preform manufacturing process, and the inner jacket tube is used in this embodiment for the purpose of facilitating the assembly of the preform, cleaning and sufficiently drying the above materials.
According to a capillary rod stacking method similar to the manufacturing of photonic crystal fibers in the fiber industry, sequentially inserting and assembling n 1、n2 glass sheets with different widths into a T1 inner sleeve in a staggered manner in sequence in a clean environment. The material of the glass sheet is not only suitable for quartz glass, but also various glass materials such as Schottky glass, heavy metal oxide glass and the like, and is also suitable for light-transmitting polymer materials such as light-transmitting plastic materials.
S2, filling gaps in the T1 inner sleeve by using capillary rods m, filling the gaps in the T1 inner sleeve by using the capillary rods m with refractive indexes corresponding to n1 and n2, filling n1 glass sheets by using n1, filling n2 glass sheets by using n2, and adopting glass materials corresponding to the glass sheets by using the capillary rods.
S3, carrying out optical fiber drawing on the sleeve pipe prepared according to the S2 to obtain an optical fiber, slowly erecting the T1 inner sleeve pipe, pulling the cone end downwards, inserting the T1 inner sleeve pipe into the outer sleeve pipe T2 connected with the extension pipe, installing a plug for wire drawing sealing on the extension pipe of the outer sleeve pipe T2, erecting a prefabricated rod on a feeding mechanism of a wire drawing tower, entering the prefabricated rod into a furnace, slowly heating the prefabricated rod to 2250 ℃, preserving heat, turning around, and opening vacuumizing after turning around so as to eliminate gas in the prefabricated rod. The fiber was subjected to filament control to prepare a small-diameter polarization-maintaining fiber having a cladding diameter of 80 μm and an outer coating diameter of 135. Mu.m.
After the optical fiber is predicted to be drawn, the refractive index difference of the optical fiber core region becomes gentle due to the equal-proportion attenuation and high-temperature diffusion of the multi-layer ribbon-shaped high refractive index material in the preform. As shown in fig. 4 to 8, the panda-type polarization maintaining fiber is a typical stress birefringence fiber, the birefringence of the panda-type polarization maintaining fiber is derived from the thermal stress in the material and the mechanical stress outside the material, the material generates birefringence when the stress causes the change of the refractive index of the material, namely the elasto-optical effect, the refractive index distribution of the fiber end face, the fast axis and the slow axis are as shown in fig. 4, 5 and 6, and the refractive index distribution of the panda-type polarization maintaining fiber is obviously different along different axes, namely the slow axis is the axis with the highest refractive index in the core region, and the fast axis is the axis with the lowest refractive index. The forming of the fast and slow axes is realized by punching the preformed rod and inserting a stress rod with very high thermal expansion coefficient in the air.
Fig. 7 and 8 are estimated equivalent refractive index distributions corresponding to different light incidence angles of the optical fiber prepared according to embodiments 4 and 5, in which fig. 7 is a fast axis of the refractive index distribution corresponding to the light incident into the optical fiber from the direction parallel to the glass sheet, as shown in fig. 5, and fig. 8 is a slow axis of the refractive index distribution corresponding to the polarization maintaining optical fiber from the direction perpendicular to the glass sheet, as shown in fig. 6, because the fast axis and the slow axis have different refractive indexes, the propagation constants βx and βy of the two orthogonal modes are different, thus having polarization maintaining performance, and the actual polarization maintaining effect can be freely designed according to the conditions of the refractive index of the n1 wave plate, the refractive index of the n2 wave plate, the thickness of the wave plate therebetween, and the like.
Mode birefringence B refers to the refractive index difference between the X-axis and Y-axis of the polarization maintaining fiber, and can be expressed as:
B＝nx-ny＝(λ/2π)(βx-βy)
In this example, the average value of n x was 0.006, the average value of n y was 0.0054, and the b value was 0.0006.
Light is transmitted in the polarization maintaining fiber, and the mode is excited due to the mode birefringence of the polarization maintaining fiberAnd coupled modeWhen the phase difference changes by 2 pi, the transmission length of the light in the polarization maintaining optical fiber is the beat length of the polarization maintaining optical fiber, and the beat length of the polarization maintaining optical fiber is in millimeter magnitude. The beat length of the polarization maintaining fiber can be calculated by the following formula:
Lb＝λ/B，
the method comprises the following steps of:
In this example, the average value of n x was 0.006, the average value of n y was 0.0054, and the b value was 0.0006.
In this example 1310nm beat length L b = 2.18mm
The 1550nm beat length L b = 2.58mm in this example
According to the calculation, the mode birefringence B value and the beat length of the optical fiber in the example are equal to those of panda type polarization maintaining optical fibers which are mainstream in the market at present.
The above embodiments are merely preferred embodiments of the present application, and should not be construed as limiting the present application, and the embodiments and features of the embodiments of the present application may be arbitrarily combined with each other without collision. The protection scope of the present application is defined by the claims, and the protection scope includes equivalent alternatives to the technical features of the claims. I.e., equivalent replacement modifications within the scope of this application are also within the scope of the application.
Claims (7)
1. An optical fiber preform, characterized by: the light-transmitting device comprises a sleeve (1), wherein the sleeve (1) is of a hollow structure, a plurality of light-transmitting sheets (2) are filled in the sleeve (1), and capillary rods (3) are filled between the light-transmitting sheets (2) and the sleeve (1); the capillary rod (3) corresponds to the refractive index of the light-transmitting sheets (2), the plurality of light-transmitting sheets (2) comprise first light-transmitting sheets (2-1) and second light-transmitting sheets (2-2) which are arranged in a staggered mode, and the refractive indexes of the first light-transmitting sheets (2-1) and the second light-transmitting sheets (2-2) are different.
2. An optical fiber preform according to claim 1, wherein: the thickness of the plurality of light-transmitting sheets (2) is the same.
3. An optical fiber preform according to claim 1, wherein: the thickness of the plurality of light-transmitting sheets (2) is different.
4. An optical fiber preform, characterized by: including sleeve pipe (1), sleeve pipe (1) is hollow structure, has multi-disc light-transmitting sheet (2) at sleeve pipe (1) intussuseption, light-transmitting sheet (2) are equipped with the multi-disc, and the intermediate zone on sleeve pipe cross section sets up higher refractive index light-transmitting sheet (2), and both ends set up lower refractive index light-transmitting sheet (2), and it has capillary stick (3) to fill between light-transmitting sheet (2) and sleeve pipe (1), and capillary stick (3) correspond with the refractive index of light-transmitting sheet (2), obtains geometrical birefringence polarization-preserving fiber.
5. An optical fiber preform, characterized by: the light-transmitting device comprises a sleeve (1), wherein the sleeve (1) is of a hollow structure, a plurality of light-transmitting sheets (2) are filled in the sleeve (1), and capillary rods (3) are filled between the light-transmitting sheets (2) and the sleeve (1); the light-transmitting sheets (2) are provided with a plurality of light-transmitting sheets, each light-transmitting sheet (2) comprises a first light-transmitting sheet (2-1) and a second light-transmitting sheet (2-2) which are arranged in a staggered mode, the thicknesses of the first light-transmitting sheet (2-1) and the second light-transmitting sheet (2-2) are different, and the refractive indexes are the same.
6. A method for preparing the optical fiber preform according to any one of claims 1 to 5, characterized by: the implementation steps are as follows:
s1, inserting a light-transmitting sheet into a sleeve;
S2, filling gaps in the sleeve by using a capillary rod;
s3, performing optical fiber drawing on the sleeve pipe prepared according to the step S2 to obtain the optical fiber.
7. A method of preparing an optical fiber preform according to claim 6, wherein: the specific implementation steps of the step S3 are as follows:
s31, connecting an extension tube to one side of the sleeve opposite to the tapered tube;
S32, erecting the sleeve, and downwards pulling the tapered end;
s33, installing a plug for wire drawing sealing on the sleeve extension pipe;
s34, erecting the prefabricated rod on a feeding mechanism of a wire drawing tower, enabling the prefabricated rod to enter a furnace, slowly heating, turning around the prefabricated rod, and then opening to vacuumize;
S35, controlling the filament diameter of the optical fiber to prepare the optical fiber.
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