JP5579207B2 - Optical fiber movement regulation structure - Google Patents

Description

  The present invention relates to a structure for restricting movement of an optical fiber.

  Conventionally, a structure for reinforcing a fusion spliced portion of an optical fiber and a structure for fixing a wound optical fiber are disclosed (see Patent Documents 1 to 4). In Patent Literatures 1 to 4, the movement of the optical fiber is regulated by fixing the optical fiber with a resin such as an adhesive.

JP-A-7-209542 JP 2007-271786 A Japanese Patent No. 3909119 Japanese Patent No. 4401540

  However, the conventional structure that restricts the movement of the optical fiber may be adversely affected by the leaked light when high-intensity light leaks from the optical fiber to the outside.

  The present invention has been made in view of the above, and an object of the present invention is to provide an optical fiber movement restricting structure suitable for restricting the movement of an optical fiber through which high-intensity light leaks.

  In order to solve the above-described problems and achieve the object, the movement restriction structure of the optical fiber according to the present invention is a structure that restricts the movement of the optical fiber, and includes a heat dissipator on which the optical fiber is placed, and the heat dissipation. Covering the periphery of the optical fiber placed on the body, transmitting a heat conductive member interposed between the optical fiber and the heat radiating body, leaking light from the optical fiber, and locally on the optical fiber And a transparent member fixed on the heat radiating plate so as to cross.

  In the optical fiber movement restricting structure according to the present invention as set forth in the invention described above, the transparent member has a refractive index greater than or equal to the refractive index of the cladding of the optical fiber.

  In the optical fiber movement restricting structure according to the present invention as set forth in the invention described above, the transparent member is made of glass.

  The optical fiber movement restricting structure according to the present invention is characterized in that, in the above invention, the radiator is formed using a metal member including at least one of aluminum, copper, iron, and nickel. To do.

  In the optical fiber movement restricting structure according to the present invention as set forth in the invention described above, the transparent member is transparent in a wavelength range of 900 nm to 1200 nm.

  According to the present invention, there is an effect that it is possible to realize an optical fiber movement restricting structure that is not adversely affected by light leakage from the optical fiber.

FIG. 1 is a schematic configuration diagram of an optical fiber laser to which the optical fiber movement restricting structure according to the first embodiment can be applied. FIG. 2 is a schematic diagram of an optical fiber movement restricting structure according to the first embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a schematic diagram of an optical fiber movement restricting structure according to a modification of the first embodiment. FIG. 5 is a schematic diagram of an optical fiber movement restricting structure according to the second embodiment. 6 is a cross-sectional view taken along line BB in FIG. FIG. 7 is a diagram showing a modification of the second embodiment. FIG. 8 is a schematic diagram of an optical fiber movement restricting structure according to the third embodiment. FIG. 9 is a schematic diagram of an optical fiber movement restricting structure according to the fourth embodiment.

  Embodiments of an optical fiber movement restricting structure according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Moreover, in each drawing, the same code | symbol is attached | subjected suitably to the same or corresponding element. Furthermore, it should be noted that the drawings are schematic, and dimensional relationships between elements may differ from actual ones. Even between the drawings, there are cases in which portions having different dimensional relationships and ratios are included.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of an optical fiber laser to which the optical fiber movement restricting structure according to the first embodiment can be applied. As shown in FIG. 1, the optical fiber laser 1 includes a plurality of pumping light sources 2, a TFB (Tapered Fiber Bundle) 3 that combines a plurality of pumping lights output from the plurality of pumping light sources 2, and an FBG (Fiber). Bragg Grating) 4a, a double-clad optical fiber 4, a rare-earth-doped optical fiber 5 that is a double-clad optical fiber that functions as an amplification medium with a rare-earth element added to the core, and a double-clad optical fiber 6 that has an FBG 6a. Single mode optical fiber 7. The double clad optical fiber 6 and the single mode optical fiber 7 are fusion-bonded by a fusion-bonding portion 8. An output end 9 is provided at one end of the single mode optical fiber 7. The FBGs 4a and 6a constitute an optical resonator.

  The optical fiber laser 1 has a so-called double clad excitation structure. For example, by supplying excitation light having a wavelength of 915 nm to the rare earth-doped optical fiber 5 in which ytterbium (Yb) is added as a rare earth element to the core, the output end 9 has an intensity of, for example, 300 W to 500 W. .1 μm wavelength band laser light can be output. As described above, since the intensity of the laser beam is very high, for example, even if there is a light loss of only 0.1 dB (about 2%) at the fusion splice 8, the energy lost there is very high. is there.

  The optical fiber movement restricting structure according to the first embodiment described below is applied in the vicinity of the fusion splicing portion 8.

  FIG. 2 is a schematic diagram of an optical fiber movement restricting structure according to the first embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG. As shown in FIGS. 2 and 3, an optical fiber movement restricting structure (hereinafter abbreviated as a movement restricting structure) 20 includes a heat radiating plate 21 that is a heat radiating member and a heat conductive silicone resin 22 that is a heat conductive member. And a transparent member 23 and a silicone adhesive 24.

  The double clad optical fiber 6 includes a core 6a, a clad 6b that covers the core 6a and functions as an inner clad, and a resin coating 6c that covers the clad 6b and also functions as an outer clad. The single mode optical fiber includes a core 7a, a clad 7b that covers the core 7a, and a resin coating 7c that covers the clad 7b.

  In the movement restricting structure 20, the heat radiating plate 21 formed with the V-groove 21 a is a fusion spliced by removing a part of the coatings 6 c and 7 c of the double clad optical fiber 6 and the single mode optical fiber 7 in the longitudinal direction. The incoming connection 8 is placed. Here, the fusion splicing portion 8 indicates a portion including the fusion splicing point 8a from which the coatings 6c and 7c are removed. Further, the heat-conductive silicone resin 22 having a refractive index higher than that of the clads 6 b and 7 b of each optical fiber covers the fusion splicing portion 8. The thermally conductive silicone resin 22 is interposed between the optical fibers 6 and 7 and the heat sink 21.

  Further, the transparent member 23 is disposed so as to locally traverse the fusion splicing portion 8. Both ends of the transparent member 23 are fixed on the heat sink 21 with a silicone adhesive 24. The double clad optical fiber 6 is fixed to the heat sink 21 by directly applying the silicone adhesive 24 to the coating 6c. The transparent member 23 locally crosses the fusion splicing portion 8 to prevent the fusion splicing portion 8 from being lifted, and restricts the movement of the optical fibers 6 and 7 in the Y-axis direction in FIG. ing.

  The light propagating in the clad 6b, 7b of the fusion splicing part 8 and the light leaking from the core 6a to the clad 7b at the fusion splicing point 8a cover the fusion splicing part 8 and are higher than the refractive index of the clad 6b, 7b. The thermally conductive silicone resin 22 having a refractive index is emitted out of the clads 6b and 7b and becomes leaked light L2. A part of the leakage light L2 is absorbed by the heat conductive silicone resin 22 and converted into heat and conducted to the heat radiating plate 21, but most of the light leaks through the heat conductive silicone resin 22 and is absorbed by the heat radiating plate 21 or space. To be released. The heat sink 21 converts the absorbed light into heat and dissipates it to the outside. The heat radiating plate 21 preferably has a high thermal conductivity, and is, for example, a metal member including at least one of aluminum, copper, iron, and nickel.

  Part of the leaked light L2 that has passed through the heat conductive silicone resin 22 is transmitted through the transparent member 23, and further part of the light is reflected by the boundary surface between the transparent member 23 and air, but the transparent member 23 is fused. Therefore, the amount of reflected light at the boundary surface is reduced. For this reason, the leakage light L2 from the fusion splicing part 8 is reflected and does not enter the coating 7c or other components, so that deterioration of the part including the fusion splicing part 8 can be suppressed.

  The transparent member 23 is made of glass such as an optical fiber or a glass plate, and is a member that transmits the leaked light L2 from the fusion splicing portion 8.

  The transparent member 23 can be constituted by, for example, one in which 1 to 6 optical fibers having an outer diameter of 125 to 200 μm are arranged in parallel, or a glass plate having the same width. As a result, the transparent member 23 crosses the fusion splicing portion 8 locally.

  If the transparent member 23 has a refractive index equal to or higher than the refractive indexes of the claddings 6b and 7b, the leakage light L2 is likely to leak into the transparent member 23, which is preferable. As a result, even if the transparent member 23 is disposed across the fusion splicing portion 8, the leaked light L <b> 2 is less likely to stay at the crossing portion, and is thus easily emitted to the outside.

  Note that the transparent member 23 and the thermally conductive silicone resin 22 may leak light L2 even if they are slightly lower than the refractive indexes of the claddings 6b and 7b as long as they are equal to or higher than the refractive indexes of the claddings 6b and 7b. As a factor of the above, it is possible to obtain a component with a small incident angle to the outer peripheral surface of the claddings 6b and 7b caused by the fusion loss and an effect of emitting the cladding mode. That is, by selecting the refractive indexes of the transparent member 23 and the heat conductive silicone resin 22, the degree of diffusion of the leaked light L2 may be adjusted to avoid abrupt diffusion of the leaked light L2.

(Modification)
FIG. 4 is a schematic diagram of an optical fiber movement restricting structure according to a modification of the first embodiment. As shown in FIG. 4, the movement restricting structure 20 </ b> A has a configuration in which the photodetector 25 </ b> A is further provided on the heat radiating plate 21 in the movement restricting structure 20 shown in FIG. 2.

  In the movement restricting structure 20A, a part of the leaked light L3 of the leaked light L2 is detected by the photodetector 25A. As described above, by providing the photodetector 25A on the heat radiating plate 21, the temperature influence on the photodetector 25A can be suppressed, so that the leakage light L3 can be detected stably.

(Embodiment 2)
The optical fiber movement restricting structure according to the second embodiment described below is applied to the rare earth-doped optical fiber 5 of the optical fiber laser 1 shown in FIG.

  FIG. 5 is a schematic diagram of an optical fiber movement restricting structure according to the second embodiment. 6 is a cross-sectional view taken along line BB in FIG. As shown in FIGS. 5 and 6, the movement restricting structure 30 includes a heat radiating plate 31, a heat conductive silicone resin 32, a transparent member 33, a silicone adhesive 34, and a double-sided tape 35.

  The rare earth-doped optical fiber 5 includes a core 5a, a cladding 5b that covers the core 5a and functions as an inner cladding, and a resin coating 5c that covers the cladding 5b and also functions as an outer cladding. In the movement restricting structure 30, the heat radiating plate 31 mounts the rare earth-doped optical fiber 5 in a wound state. A thin double-sided tape 35 sticks the rare earth-doped optical fiber 5 to the heat sink 31. The thermally conductive silicone resin 32 covers the rare earth-doped optical fiber 5. The thermally conductive silicone resin 32 is interposed between the rare earth-doped optical fiber 5 and the heat sink 31.

  Further, a plurality of (for example, four) transparent members 33 are disposed so as to locally traverse the rare earth-doped optical fiber 5. Both ends of the transparent member 33 are fixed on the heat radiating plate 31 with a silicone adhesive 34. The transparent member 33 locally traverses the rare earth-doped optical fiber 5 to prevent the wound rare earth-doped optical fiber 5 from being lifted or displaced. One of the X-axis direction and the Y-axis direction in FIG. The movement of the rare earth-doped optical fiber 5 to both is regulated.

  The light incident on the coating 5c of the rare earth-doped optical fiber 5 is emitted outside the coating 5c by the thermally conductive silicone resin 32 having a refractive index higher than that of the cladding 5b, and becomes leaked light L4. A part of the leaked light L4 is absorbed by the heat conductive silicone resin 32 and converted into heat and conducted to the heat radiating plate 31, but most of the light leaks through the heat conductive silicone resin 32 and the double-sided tape 35 and is absorbed by the heat radiating plate 31. Or released into space. The heat radiating plate 31 converts the absorbed light into heat and dissipates it to the outside. The heat radiating plate 31 preferably has a high thermal conductivity like the heat radiating plate 21 and is, for example, a metal member containing at least one of aluminum, copper, iron, and nickel.

  By interposing the heat conductive silicone resin 32 between the rare earth-added optical fiber 5 and the double-sided tape 35 and the heat radiating plate 31, the heat generated in the rare earth-added optical fiber 5 is thermally conductive silicone resin 32 and the double-sided tape 35. It becomes easy to be transmitted to the heat sink 31 via the. Thereby, efficient heat dissipation can be performed.

  Part of the leaked light L4 that has passed through the thermally conductive silicone resin 32 passes through the transparent member 33, and further part of the light is reflected at the boundary surface between the transparent member 33 and air. Therefore, the amount of reflected light at the boundary surface is reduced. For this reason, the leakage light L4 from the rare earth-added optical fiber 5 is reflected and does not enter the coating 5c or other components, so that the deterioration of the rare earth-added optical fiber 5 can be suppressed.

  Similarly to the transparent member 23, the transparent member 33 is made of glass such as an optical fiber or a glass plate, and is a member that transmits the leakage light L <b> 3 from the rare earth-doped optical fiber 5. The transparent member 33 can be configured by, for example, one in which 1 to 6 optical fibers having an outer diameter of 125 to 200 μm are arranged in parallel, or a glass plate having the same width. As a result, the transparent member 33 locally traverses the rare earth-doped optical fiber 5.

  If the transparent member 33 has a refractive index equal to or higher than the refractive index of the clad 5 b as in the transparent member 23, it is preferable because the leaked light L <b> 3 easily leaks into the transparent member 33. As a result, even if the transparent member 33 is disposed across the rare earth-doped optical fiber 5, the leaked light L4 is less likely to stay at the transverse portion, and is thus easily emitted to the outside.

  The transparent member 33 and the heat conductive silicone resin 32 cause leakage light L4 even if they are slightly lower than the refractive index of the clad 5b as long as the refractive index of the clad 5b is equal to or higher. The effect of emitting the cladding mode can be obtained. That is, by selecting the refractive indexes of the transparent member 33 and the heat conductive silicone resin 32, the degree of diffusion of the leaked light L4 may be adjusted to avoid abrupt diffusion of the leaked light L4.

(Modification)
FIG. 7 is a diagram showing a modification of the second embodiment. In the second embodiment shown in FIGS. 5 and 6, the rare earth-doped optical fiber 5 is wound in a state of being spaced apart from each other. However, as shown in FIG. You may wind so that it may become. The shape of the winding may be a disc shape, a conical shape, an elliptical plate shape, a spiral shape, an annular shape, a torus shape, a column shape, or a shape formed by a combination of all or a part of these shapes.

(Embodiment 3)
The optical fiber movement restricting structure according to the third embodiment described below is applied to any position on the rear stage side (output end 9 side) of the rare earth-doped optical fiber 5 of the optical fiber laser 1 shown in FIG. Is. In this Embodiment 3, the case where it applies to a part of double clad optical fiber 6 as an example is demonstrated.

  FIG. 8 is a schematic diagram of an optical fiber movement restricting structure according to the third embodiment. As shown in FIG. 8, the movement restricting structure 40 is similar to the movement restricting structure 20 according to the first embodiment. The heat radiating plate 21, the thermally conductive silicone resin 22, the transparent member 23, the silicone adhesive 24, and the like. It has.

  In the movement restricting structure 40, the heat radiating plate 21 in which the V-groove 21 a is formed has a coating removing portion 6 d on which the coating 6 c of the double clad optical fiber 6 is removed. Further, the thermally conductive silicone resin 22 having a refractive index higher than that of the clad 6b of the double clad optical fiber 6 covers the coating removal portion 6d. The thermally conductive silicone resin 22 is interposed between the double clad optical fiber 6 and the heat sink 21.

  Further, the transparent member 23 is disposed so as to locally traverse the coating removal portion 6d. Both ends of the transparent member 23 are fixed on the heat sink 21 with a silicone adhesive 24. The double clad optical fiber 6 is fixed to the heat sink 21 by directly applying the silicone adhesive 24 to the coating 6c. The transparent member 23 locally traverses the coating removal portion 6d to prevent the coating removal portion 6d from rising, and restricts the movement of the double clad optical fiber 6 in the direction perpendicular to the paper surface.

  Here, of the pumping light output from the pumping light source 2, pumping light that has not been used for optical amplification in the rare earth-doped optical fiber 5 is output from the rare earth-doped optical fiber 5 as residual pumping light, and then double-clad optical fiber. 6 is propagated. This residual excitation light is confined in the double clad optical fiber 6 by a coating 6 c that functions as an outer clad. Therefore, in the coating removal portion 6d from which the coating 6c has been removed, the heat removal silicone resin 22 covering the coating removal portion 6d and having a refractive index higher than the refractive index of the cladding 6b is emitted out of the cladding 6b and leaked light. L5. A part of the leaked light L5 is absorbed by the heat conductive silicone resin 22 and converted into heat and conducted to the heat radiating plate 21, but most of the light leaks through the heat conductive silicone resin 22 and is absorbed by the heat radiating plate 21. Released into space. Thus, the movement restricting structure 40 can process the residual excitation light so that the residual excitation light is not output from the output end 9.

  In addition, if the transparent member 23 and the heat conductive silicone resin 22 are equal to or higher than the refractive index of the clad 6b, even if it is slightly lower than the refractive index of the clad 6b, it causes the leakage light L5. The effect of emitting the cladding mode can be obtained. That is, by selecting the refractive indexes of the transparent member 23 and the thermally conductive silicone resin 22, the degree of divergence of the leaked light L5 may be adjusted to avoid abrupt divergence of the leaked light L5.

  Part of the leaked light L5 that has passed through the heat conductive silicone resin 22 is transmitted through the transparent member 23, and further part of the light is reflected at the boundary surface between the transparent member 23 and the air. Due to the configuration that traverses locally, the amount of reflected light at the interface is reduced. For this reason, the leakage light L5 from the coating removal part 6d is reflected and does not enter the coating 6c or other components, so that deterioration of the portion including the coating removal part 6d can be suppressed.

(Embodiment 4)
The optical fiber movement restricting structure according to Embodiment 4 described below is applied to the vicinity of the output end 9 of the optical fiber laser 1 shown in FIG.

  FIG. 9 is a schematic diagram of an optical fiber movement restricting structure according to the fourth embodiment. As shown in FIG. 9, the movement restricting structure 50 is similar to the movement restricting structure 20 according to the first embodiment. The heat radiating plate 21, the heat conductive silicone resin 22, the transparent member 23, the silicone adhesive 24, and the like. It has.

  In the movement restricting structure 50, the heat radiating plate 21 in which the V-groove 21 a is formed has a coating removing portion 7 d from which the coating 7 c of the single mode optical fiber 7 is removed. A thermally conductive silicone resin 22 having a refractive index higher than that of the clad 7b of the single mode optical fiber 7 covers a part of the coating removal portion 7d. The thermally conductive silicone resin 22 is interposed between the single mode optical fiber 7 and the heat sink 21. The output end 9 is obtained by obliquely cutting the tip of the coating removing portion 7d of the single mode optical fiber 7.

  Further, the transparent member 23 is disposed so as to locally traverse the coating removal portion 7d. Both ends of the transparent member 23 are fixed on the heat sink 21 with a silicone adhesive 24. The single mode optical fiber 7 is fixed to the heat sink 21 by directly applying a silicone adhesive 24 to the coating 7c. The transparent member 23 locally traverses the coating removal portion 6d to prevent the coating removal portion 7d from rising, and restricts movement of the single mode optical fiber 7 in a direction perpendicular to the paper surface.

  Here, when the laser beam L1 is output from the output end 9, a part thereof is reflected by the output end 9, is confined in the clad 7b as reflected light, and propagates to the left side of the drawing. This reflected light is emitted out of the cladding 7b by the thermally conductive silicone resin 22 that covers the coating removal portion 7d and has a refractive index higher than that of the cladding 7b, and becomes leakage light L6. A part of the leaked light L6 is absorbed by the heat conductive silicone resin 22 and converted into heat and conducted to the heat radiating plate 21, but most of the light leaks through the heat conductive silicone resin 22 and is absorbed by the heat radiating plate 21 or space. To be released. Thus, the movement restricting structure 50 prevents the reflected light from the output end 9 from reaching the coating 7c. This prevents the coating 7c from being burned out by the energy of the reflected light.

  In addition, if the transparent member 23 and the heat conductive silicone resin 22 are equal to or higher than the refractive index of the clad 7b, even if it is slightly lower than the refractive index of the clad 7b, it causes the leakage light L6. The effect of emitting the cladding mode can be obtained. That is, by selecting the refractive indexes of the transparent member 23 and the heat conductive silicone resin 22, the degree of diffusion of the leaked light L6 may be adjusted to avoid abrupt diffusion of the leaked light L6.

  Part of the leaked light L6 that has passed through the heat conductive silicone resin 22 is transmitted through the transparent member 23, and further part of the light is reflected at the boundary surface between the transparent member 23 and the air. Due to the configuration that traverses locally, the amount of reflected light at the interface is reduced. For this reason, since the leaked light L5 from the coating removing part 6d is reflected and does not enter the coating 7c or other components, it is possible to suppress deterioration of the portion including the coating removing part 7d.

  As described above, the movement restricting structure according to each embodiment of the present invention can prevent adverse effects due to leaked light even when high-intensity light leaks from the optical fiber to the outside. Further, since it is a simple structure and is not configured to increase the loss of the optical fiber by applying stress to the optical fiber, it is suitable for regulating the movement of the optical fiber through which high-intensity light leaks.

  Instead of the heat conductive silicone resins 22 and 32, other heat conductive resins or other heat conductive members such as heat conductive grease may be used. By using thermally conductive grease, the heat dissipation effect is further enhanced, and the stress on each of the optical fibers 5, 6, and 7 can be further suppressed. Further, the transparent members 23 and 33 may be made of crystallized glass such as Neoceram (registered trademark). The transparent members 23 and 33 should just be transparent in the wavelength of leakage light, for example, it is preferable that it is transparent in the wavelength range of 900 nm-1200 nm.

  Further, the present invention is not limited by the above embodiment. What was comprised combining each component mentioned above suitably is also contained in this invention. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

1 Optical fiber laser 2 Excitation light source 3 TFB
4, 6 Double clad optical fiber 4a, 6a FBG
DESCRIPTION OF SYMBOLS 5 Rare earth doped optical fiber 5a, 6a, 7a Core 5b, 6b, 7b Clad 5c, 6c, 7c Coating 6d, 7d Coating removal part 7 Single mode optical fiber 8 Fusion splicing part 8a Fusion splicing point 9 Output end 20, 20A , 30, 40, 50 Movement restriction structure 21, 31 Heat sink 21a V groove 22, 32 Thermally conductive silicone resin 23, 33 Transparent member 24, 34 Silicone adhesive 25A Photo detector 35 Double-sided tape L1 Laser light L2, L3, L4, L5, L6 Leakage light

Claims (5)

A structure that regulates the movement of an optical fiber,
A radiator for placing the optical fiber;
Covering the periphery of the optical fiber placed on the radiator, a thermally conductive member interposed between the optical fiber and the radiator,
A transparent member that transmits leakage light from the optical fiber and is fixed on the heat sink so as to cross over the optical fiber over a range of 125 to 1200 μm along the axial direction of the optical fiber;
An optical fiber movement restricting structure characterized by comprising: The optical fiber movement restricting structure according to claim 1, wherein the transparent member has a refractive index equal to or higher than a refractive index of a clad of the optical fiber. The transparent member, movement restriction mechanism of the optical fiber according to claim 1 or 2, characterized in that it consists of glass. The radiator is aluminum, copper, iron, and restriction of the movement of the optical fiber according to any one of claims 1-3, characterized in that it is formed using a metal member including at least one nickel Construction. The transparent member, movement restriction mechanism of the optical fiber according to any one of claims 1-4, characterized in that the transparent in the wavelength range of 900Nm～1200nm.

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