JP5366488B2 - Optical fiber reel and optical device - Google Patents

Description

  The present invention relates to an optical fiber reel that accommodates an optical fiber and an optical device using the optical fiber reel.

Conventionally, a rare earth doped optical fiber amplifier using a rare earth doped optical fiber doped with rare earth ions such as erbium (Er) and yttrium (Yb) in the core is known. In such a rare earth-doped optical fiber amplifier, an optical fiber reel is used to accommodate the optical fiber (see, for example, Patent Document 1).
JP-A-8-337361

  By the way, although a circular reel is generally used as the optical fiber reel, the size of the reel is limited by the minimum bending radius of the wound optical fiber. That is, in order to suppress macrobend loss due to bending of the optical fiber, the radius of the reel needs to be designed to be greater than the minimum bending radius of the optical fiber. Since an optical fiber of several meters to several tens of meters must be accommodated in such a radius reel, there is a problem that it is difficult to reduce the size of the optical fiber reel.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a small optical fiber reel and an optical device using an optical fiber for the optical fiber reel.

  In order to solve the above-described problems, an optical fiber reel according to an aspect of the present invention is an optical fiber reel that accommodates an optical fiber, and includes a first surface and a second surface opposite to the first surface. Penetrating the base portion, the first convex portion projecting on the first surface of the base portion, the second convex portion projecting on the second surface of the base portion, A through hole communicating with the first surface and the second surface; When the optical fiber is accommodated, a part of the optical fiber is spirally wound on the first surface along the first convex part, and the other part of the optical fiber is along the second convex part. A portion of the optical fiber between the part of the optical fiber and the other part of the optical fiber is inserted into the through hole.

  According to this aspect, since the optical fiber can be wound separately on the first surface and the second surface of the base part, compared with the case where the optical fiber is wound only on one surface in a spiral shape. Thus, the size of the optical fiber reel in the radial direction can be reduced. Further, the size of the optical fiber reel in the height direction can be reduced as compared with the case where the optical fiber is spirally wound.

  Moreover, according to this aspect, the both ends of an optical fiber can be pulled out from the outer peripheral side of an optical fiber reel. Thereby, even after the optical fiber is completely stored in the optical fiber reel, the length of the fiber drawn from the optical fiber reel can be easily changed at both ends of the optical fiber.

  Furthermore, when the optical fiber reel is used for a high-power fiber laser or the like, the stored fiber generates heat, so it is necessary to cool the generated heat. According to this aspect, the stored optical fiber is Since it is in contact with the first surface or the second surface of the base portion, the heat generated in the optical fiber can be efficiently cooled by the base portion.

  You may further provide the 1st cover and 2nd cover which respectively cover the upper part of a 1st surface and a 2nd surface so that an optical fiber may be contact | connected. In this case, the stored optical fiber is in contact with not only the first surface and the second surface but also the first cover and the second cover, so that the generated heat can be cooled more efficiently.

  The first surface and / or the second surface may be formed such that the surface thereof has light absorption. The base portion may be formed of a light-absorbing material such as stainless steel, or a light-absorbing coating such as black alumite may be applied to the surfaces of the first surface and the second surface. In this case, for example, even if the optical fiber coating has some scratches, leakage of light to the outside of the optical fiber reel can be prevented.

  The outer diameter of the first convex portion and / or the second convex portion may be an outer diameter that attenuates the higher-order mode of the wound optical fiber and propagates the fundamental mode to the center. In this case, when the optical fiber reel is used for an optical fiber amplifier, the emitted laser light becomes a single mode, and the beam quality can be improved.

  A guide portion for preventing the optical fiber from floating may be further provided above the first surface and / or the second surface. In this case, workability when winding the optical fiber around the optical fiber reel can be improved.

  The first convex portion and / or the second convex portion may be formed in a bowl shape having one or more constricted portions. In this case, an inflection point is generated in the optical fiber wound around the optical fiber reel. When an optical fiber reel is used for an optical fiber amplifier, the bias of the light distribution in the optical fiber is corrected at the inflection point of the optical fiber, so that the absorption efficiency of the pumping light in the core is increased, and the optical fiber having a high amplification factor. An amplifier can be configured.

  Another aspect of the present invention is an optical device. This optical device is an optical device in which an optical fiber is accommodated in the above-described optical fiber reel, and the optical fiber wound on the first surface and the second surface is fixed by an elastic resin.

  According to this aspect, since the optical fiber is fixed with the elastic resin, even after the fixing, by pulling the end of the optical fiber, the resin is relatively easily broken, and the optical fiber having a necessary length can be taken out. .

  The optical fiber wound around the optical fiber reel may be a double clad fiber, and the elastic resin may be an elastic resin having a refractive index lower than that of the first clad of the double clad fiber. In this case, for example, even if the optical fiber coating has some scratches, leakage of light to the outside of the optical fiber reel can be prevented.

  According to the present invention, a small-sized optical fiber reel and an optical device using the optical fiber reel can be provided.

  FIG. 1 is a diagram for explaining a Fabry-Perot type optical amplifying apparatus 100 in which an optical fiber reel according to an embodiment of the present invention is used. The Fabry-Perot type optical amplifying apparatus 100 includes a non-reflection terminator 101, a plurality of pumping semiconductor lasers 102, a pump combiner 104, a high reflectivity FBG (Fiber Bragg Grating) 106, and a rare earth doped light that is a double clad fiber. A fiber 108, a low reflectivity FBG 110, and an isolator 112 are provided.

  In the Fabry-Perot optical amplifier 100, multimode light emitted from a plurality of pumping semiconductor lasers 102 is coupled to the first cladding of the rare earth-doped optical fiber 108 via the high reflectivity FBG 106 by the pump combiner 104.

  When pump light is introduced into the first cladding of the rare earth-doped optical fiber 108, when the pump light propagating through the first cladding crosses the core, the rare earth ions absorb the energy of the pump light, and the rare earth-doped optical fiber 108 Light having a wavelength in the reflection band of the high reflectivity FBG 106 and the low reflectivity FBG 110 disposed at both ends is amplified by the stimulated emission phenomenon, and is output as laser light through the isolator 112.

  The rare earth doped optical fiber 108 is an optical fiber having a core doped with rare earth ions. The rare earth ions to be doped are not particularly limited, and may be erbium (Er), praseodymium (Pr), thulium (Tm), yttrium (Yb), or the like. In particular, an optical fiber doped with yttrium is often used for a high-power fiber laser device. In the case of using an optical fiber doped with yttrium, an optical fiber having a length of several tens of meters is used in consideration of a technique for adding yttrium to the core and high efficiency. Further, in order to introduce high-intensity excitation light into the rare earth-doped optical fiber 108, an optical fiber having a cladding diameter of about 400 μm is often used.

  FIG. 2 is a perspective view of the optical fiber reel 10 according to the embodiment of the present invention. FIG. 3 is an exploded perspective view of the optical fiber reel 10. As shown in FIGS. 2 and 3, the optical fiber reel 10 includes a base portion 12, a first cover 14, a second cover 16, a first guide portion 18, and a second guide portion 20. The optical fiber reel 10 has a structure in which a base portion 12 is sandwiched between a first cover 14 and a second cover 16.

  FIG. 4 is a side view of the base portion 12. As shown in FIG. 4, the base portion 12 is formed in a disc shape and has a first surface 26 and a second surface 28 opposite to the first surface 26. On the 1st surface 26, the 1st convex-shaped part 22 is protrudingly provided by the annular | circular shape. About half of the rare earth-doped optical fiber 108 is spirally wound on the first surface 26 along the first convex portion 22. The first convex portion 22 is provided with first groove portions 30 for fitting the first guide portions 18 at intervals of 90 degrees in the circumferential direction. On the second surface 28, the second convex portion 24 is provided in an annular shape. The remaining half of the rare-earth-doped optical fiber 108 is spirally wound on the second surface 28 along the second convex portion 24. The second convex portion 24 is provided with second groove portions 32 for fitting the second guide portions 20 at intervals of 90 degrees in the circumferential direction. The annular first convex portion 22 and the second convex portion 24 have the same outer diameter and are concentric with the base portion 12.

  The outer diameters of the annular first convex portion 22 and the second convex portion 24 are set according to the rare earth doped optical fiber 108. Specifically, the outer diameters of the first convex portion 22 and the second convex portion 24 are such that the higher-order mode of the wound rare-earth doped optical fiber 108 is attenuated and the fundamental mode propagates to the center. Is set. As a result, the laser light emitted from the Fabry-Perot type optical amplifying apparatus 100 becomes a single mode, and the beam quality can be improved. In addition, when the output light of a single mode is not requested | required, the outer diameter of the 1st convex part 22 and the 2nd convex part 24 is not limited above.

  As shown in FIGS. 3 and 4, the base portion 12 is provided with a through hole 34 that penetrates the base portion 12 and communicates the first surface 26 and the second surface 28. The through hole 34 is a long arc-shaped hole that extends along the outer walls of the first convex portion 22 and the second convex portion 24. A portion between the portion wound on the first surface 26 and the portion wound on the second surface 28 in the rare earth-doped optical fiber 108 is inserted into the through hole 34. The circumferential wall surface 36 in the through hole 34 is formed in a slope shape inclined with respect to the axial direction of the base portion 12. Thereby, the fiber can be smoothly inserted from the first surface 26 side of the base portion 12 to the second surface 28 side.

  The first surface 26 and the second surface 28 of the base portion 12 are preferably formed so that the surfaces thereof have light absorption. This can be realized by forming the base portion 12 with a light-absorbing material such as stainless steel, or by applying a light-absorbing coating such as black alumite on the surfaces of the first surface 26 and the second surface 28. . In this case, for example, even if the coating of the rare earth-doped optical fiber 108 has some scratches, the light leaking from the scratch of the rare earth doped optical fiber 108 is applied to the first surface 26 and the second surface 28 in the vicinity of the scratch. Therefore, the leakage of light to the outside of the optical fiber reel 10 can be prevented.

  Above the first surface 26 and the second surface 28 of the base portion 12, a first guide portion 18 and a second guide portion 20 which are plate-like members formed in a cross shape are provided. When the rare-earth doped optical fiber 108 is wound on the first surface 26 and the second surface 28, the first guide portion 18 and the second guide portion 20 are perpendicular to the first surface 26 or the second surface 28. Provided to prevent overlapping in direction. Accordingly, the distance between the first surface 26 and the first guide portion 18 and the distance between the second surface 28 and the second guide portion 20 are slightly larger than the outer diameter of the rare earth-doped optical fiber 108 and are rare earth. The value is set to be smaller than twice the outer diameter of the doped optical fiber 108. For example, when the outer diameter of the rare-earth doped optical fiber 108 including the coating is 500 μm, the distance between the first surface 26 and the first guide portion 18 and the distance between the second surface 28 and the second guide portion 20. Is set to about 550 μm. The distance between the first surface 26 and the first guide portion 18 and the distance between the second surface 28 and the second guide portion 20 are the first groove portion 30 formed in the first convex portion 22, the first It can be adjusted by changing the depth of the second groove 32 formed in the two convex portions 24.

  The first cover 14 and the second cover 16 are provided so as to cover the first surface 26 and the second surface 28 of the base portion 12, respectively. The distance between the first cover 14 and the first surface 26, the distance between the second cover 16 and the second surface 28, the distance between the first surface 26 and the first guide portion 18, the second surface 28 is set to be smaller than the distance between the second guide portion 20 and the first cover 14 is provided so as to press the rare earth-doped optical fiber 108 wound on the first surface 26 against the base portion 12. The second cover 16 is provided so as to press the rare earth-doped optical fiber 108 wound on the second surface 28 against the base portion 12. Even if the rare earth-doped optical fiber 108 is pressed against the base portion 12, the contact area is large, so that the coating of the rare earth-doped optical fiber 108 is not damaged, and heat dissipation is performed efficiently. The first cover 14 and the second cover 16 are groove portions 38 for fitting the first convex portion 22 and the second convex portion 24 of the base portion 12, the first guide portion 18, and the second guide portion 20. , 40 are formed.

  FIG. 5 is a diagram illustrating a state in which the rare earth-doped optical fiber 108 is accommodated in the optical fiber reel 10. FIG. 5 shows a state where the first cover 14 and the second cover 16 are removed. About half of the rare earth-doped optical fiber 108 is spirally wound on the first surface 26 along the first convex portion 22. Although not shown in FIG. 5, the remaining half of the rare earth-doped optical fiber 108 is spirally wound on the second surface 28 along the second convex portion. A portion between the portion wound on the first surface 26 and the portion wound on the second surface 28 in the rare earth-doped optical fiber 108 is inserted into the through hole 34.

  When housing the rare earth doped optical fiber 108 in the optical fiber reel 10, first, about half of the rare earth doped optical fiber 108 is passed through the through hole 34. Then, the rare earth-doped optical fiber 108 is wound around the first convex portion 22 and the second convex portion 24 on the first surface 26 side and the second surface 28 side of the base portion 12, respectively.

  When the rare earth doped optical fiber 108 is wound, the rare earth doped optical fiber 108 is wound between the first surface 26 and the first guide portion 18 and between the second surface 28 and the second guide portion 20. . The first guide portion 18 and the second guide portion 20 prevent the fiber from being lifted, and the rare-earth doped optical fiber 108 is suppressed from being double-tripled in the height direction of the optical fiber reel 10. Can be improved. Further, it is possible to prevent the rare earth doped optical fiber 108 from being damaged.

  After the rare earth doped optical fiber 108 is wound on the first surface 26 and the second surface 28, the rare earth doped optical fiber 108 is aligned by applying a certain amount of tension. Thereafter, a low refractive index resin is dropped on the side surface of the rare earth-doped optical fiber 108 and applied to the entire side surface. The low refractive index resin is preferably, for example, a two-component mixed silicone elastic resin having a lower refractive index than the first cladding of the rare earth-doped optical fiber 108. The applied resin has a role of fixing the fiber by filling a space formed between the fibers. By using an elastic resin, even after fixing, the resin can be relatively easily broken by pulling the end of the optical fiber, and an optical fiber having a required length can be taken out. Further, by using an elastic resin having a refractive index lower than that of the first cladding of the rare earth-doped optical fiber 108, for example, even if the optical fiber coating has some scratches, the rare earth doped optical fiber 108 leaks from the scratches. Since the light is reflected by the elastic resin and returned to the rare earth-doped optical fiber 108, the leakage of light to the outside of the optical fiber reel 10 can be prevented.

  After the resin is applied to the entire side surface of the rare earth-doped optical fiber 108, the first cover 14 and the second cover 16 are attached on the first surface 26 and the second surface 28 of the base portion 12, respectively, and the resin is cured. You may remove the 1st guide part 18 and the 2nd guide part 20 after resin hardening.

  As described above, according to the optical fiber reel 10 according to the present embodiment, the rare earth-doped optical fiber 108 can be wound separately on the first surface 26 and the second surface 28 of the base portion 12. As compared with the case where the optical fiber is wound only on one surface in a spiral shape, the size of the optical fiber reel in the radial direction can be reduced. Further, the size of the optical fiber reel in the height direction can be reduced as compared with the case where the optical fiber is spirally wound. Thus, since the optical fiber reel 10 can be reduced in size, the Fabry-Perot type optical amplifying apparatus 100 can be reduced in size.

  Further, according to the optical fiber reel 10, as shown in FIG. 5, both ends of the rare earth doped optical fiber 108 can be pulled out from the outer peripheral side of the optical fiber reel 10. Thereby, even after the rare earth doped optical fiber 108 is completely stored in the optical fiber reel 10, the length of the fiber drawn from the optical fiber reel 10 can be easily changed at both ends of the rare earth doped optical fiber 108.

  Further, according to the optical fiber reel 10, the stored rare earth doped optical fiber 108 is in contact with the first surface 26 and the second surface 28 of the base portion 12, so that the heat generated in the rare earth doped optical fiber 108 is the base. It is cooled efficiently by the part. Furthermore, in the present embodiment, since the rare earth doped optical fiber 108 is also in contact with the first cover 14 and the second cover 16, the generated heat can be cooled more efficiently.

  FIG. 6 is a plan view showing an optical fiber reel 200 according to another embodiment of the present invention. The optical fiber reel 200 is also used in the Fabry-Perot optical amplifier 100 shown in FIG. The optical fiber reel 200 differs from the optical fiber reel 10 described in FIGS. 2 to 5 in the shapes of the first convex portion 222 and the second convex portion (not shown).

  In the optical fiber reel 200, a first convex portion 222 and a second convex portion having a bowl shape are provided on the first surface 226 and the second surface (not shown) of the base portion 212, respectively. As shown in FIG. 6, the first convex portion 222 and the second convex portion are formed to have two constricted portions 227. The base portion 212 is provided with a through hole 234 that penetrates the base portion 212 and communicates the first surface 226 and the second surface.

  In the optical fiber reel 200, the rare earth-doped optical fiber 108 is spirally wound on the first surface 226 along the first convex portion 222 having a bowl shape, and the other half of the rare-earth doped optical fiber 108 has a bowl shape. It is wound in a spiral shape on the second surface along the two convex portions. Further, a portion between the portion wound on the first surface 226 and the portion wound on the second surface in the rare earth-doped optical fiber 108 is inserted into the through hole 234.

  In the optical fiber reel 200 according to the present embodiment, the first convex portion 222 and the second convex portion are formed in a bowl shape, so that an inflection point is generated in the wound rare earth-doped optical fiber 108. Since the deviation of the light intensity distribution in the cross section perpendicular to the light propagation direction in the rare earth-doped optical fiber 108 is corrected at this inflection point, the absorption efficiency of the pumping light in the core is increased, and the Fabry-Perot type optical amplifier 100 The amplification factor can be increased. Other effects such as downsizing and improvement in cooling efficiency are the same as those of the optical fiber reel 10 described with reference to FIGS.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  For example, in the above-described embodiment, the convex portion formed on the base portion has an annular shape or a hook shape, but is not limited thereto, and may be, for example, an elliptical shape.

  In the above-described embodiment, the case where the optical fiber reel is used in the Fabry-Perot type optical amplifying apparatus has been described. be able to.

  In the optical fiber reel shown in FIG. 6, the first convex portion and the second convex portion are formed in a hook shape with two constricted portions. However, if the hook shape has one or more constricted portions, it is changed to an optical fiber. Since the inflection point exists, the light absorption efficiency in the core can be increased.

It is a figure for demonstrating the Fabry-Perot type | mold optical amplifier with which the optical fiber reel which concerns on embodiment of this invention is used. 1 is a perspective view of an optical fiber reel according to an embodiment of the present invention. 1 is an exploded perspective view of an optical fiber reel according to an embodiment of the present invention. It is a side view of a base part concerning an embodiment of the invention. It is a figure which shows a mode that the rare earth doped optical fiber was accommodated in the optical fiber reel which concerns on embodiment of this invention. It is a top view which shows the optical fiber reel which concerns on another embodiment of this invention.

Explanation of symbols

  10, 200 Optical fiber reel, 12, 212 Base part, 14 First cover, 16 Second cover, 18 First guide part, 20 Second guide part, 22, 222 First convex part, 24 Second convex part , 26, 226 First surface, 28 Second surface, 34, 234 Through hole, 100 Fabry-Perot type optical amplifier, 102 Pumping semiconductor laser, 104 Pump combiner, 106 High reflectivity FBG, 108 Rare earth doped optical fiber, 110 Low reflectivity FBG, 112 isolator.

Claims (7)

An optical fiber reel for storing an optical fiber,
A flat base portion having a first surface and a second surface opposite to the first surface;
A first convex portion projecting on the first surface of the base portion;
A second convex portion protruding on the second surface of the base portion;
A through-hole penetrating the base portion and communicating the first surface and the second surface;
When the optical fiber is stored, a part of the optical fiber is spirally wound on the first surface along the first convex part, and the other part of the optical fiber is the second convex part. And a portion of the optical fiber between the part of the optical fiber and the other part of the optical fiber is inserted into the through hole ,
The optical fiber floats above the first surface and / or the second surface when the optical fiber is spirally wound along the first convex portion and / or the second convex portion. A first guide part and / or a second guide part for preventing,
The distance between the first surface and the first guide portion and / or the distance between the second surface and the second guide portion is larger than the outer diameter of the optical fiber and the outer diameter of the optical fiber. Is set to be a value smaller than twice,
An optical fiber reel characterized by that.   2. The optical fiber reel according to claim 1, further comprising a first cover and a second cover that cover the upper sides of the first surface and the second surface so as to contact the optical fiber, respectively.   3. The optical fiber reel according to claim 1, wherein the first surface and / or the second surface is formed so that a surface thereof has light absorption. 4.   The outer diameter of the first convex portion and / or the second convex portion is an outer diameter that attenuates a higher-order mode of the wound optical fiber and propagates the fundamental mode to the center. The optical fiber reel according to any one of claims 1 to 3. The optical fiber reel according to any one of claims 1 to 4 , wherein the first convex portion and / or the second convex portion are formed in a bowl shape having one or more constricted portions. . An optical device the optical fiber is accommodated in the optical fiber reel according to any one of claims 1 to 5,
An optical device, wherein the optical fiber wound on the first surface and / or the second surface is fixed by an elastic resin. The optical fiber wound around the optical fiber reel is a double clad fiber, and the elastic resin is an elastic resin having a refractive index lower than that of the first clad which is a clad positioned inward when viewed from the center of the double clad fiber. The optical device according to claim 6 , wherein:

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