JP2015132773A - Optical device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make leakage light of residual excitation light or signal light less likely to concentrate on a portion of a resin layer covering a connection part between optical fibers.SOLUTION: An optical device (1) comprises a first optical fiber (11), a second optical fiber (12), and a connection part resin layer (14) covering claddings (22 and 32) at a fusion splicing part (13) of the first and second optical fibers (11 and 12) and containing fillers (15).

Description

  The present invention relates to an optical device having a connection portion between optical fibers for transmitting laser light and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, as an optical device for transmitting laser light, for example, as shown in Patent Document 1, a signal light is amplified in a double clad fiber, and the amplified signal light is transmitted in a single clad fiber (single mode fiber). Things are known.

  Specifically, in the optical device, the double clad fiber has a core to which an active element such as a rare earth element is added, and has a first clad having a lower refractive index than the core around the core. Further, a second cladding having a lower refractive index than the first cladding is provided around the first cladding. Excitation light is introduced from the excitation light source into the first cladding around the core, and the signal light propagates in the core to which the active element is added. Thereby, the signal light is amplified in the double clad fiber, and then introduced into the single clad fiber that is fusion-spliced with the double clad fiber, and transmitted through the single clad fiber.

  Here, in addition to the signal light, the residual excitation light remaining without being absorbed by the active element is also incident from the double clad fiber to the single clad fiber. In this case, the residual excitation light generates heat in the coating in the process of propagating through the clad of the single clad fiber. This heat degrades the coating and, in the worst case, can lead to breakage of the single clad fiber.

  Further, when an axial shift occurs in the fusion spliced portion between the double clad fiber and the single clad fiber, a part of the amplified signal light is incident on the clad as leaked light from the core. In this case, since the leakage light of the signal light propagates through the clad in addition to the residual excitation light, the above problem becomes more remarkable. Such a problem is not limited to the case where the double-clad fiber and the single-clad fiber are connected, but can also occur when other optical fibers are connected.

  In order to deal with the above problems, Patent Documents 1 and 2 describe a technique in which residual excitation light is released outside the clad and is converted into heat in the vicinity of a fusion splicing portion between optical fibers. Specifically, in the configuration described in Patent Document 1, the fusion-bonded portion between the double-clad fibers is disposed in a groove formed in the heat radiating plate in a state where the coating resin layer is peeled off, and the double-clad fiber is disposed in the groove. A transparent resin having a refractive index larger than that of the clad is filled, and the fusion splicing portion is covered with a transparent resin layer (filled resin layer). Thereby, the residual excitation light leaks from the clad through the filling resin layer and is converted into heat in the heat sink.

  In the configuration described in Patent Document 2, the coating resin layer of the single clad fiber is removed and exposed in the vicinity of the fusion spliced portion between the double clad fiber and the single clad fiber. Further, the exposed portion is covered with a resin layer (filled resin layer) having a refractive index larger than that of the cladding, and the resin is covered with an aluminum block. As a result, the residual excitation light leaks from the clad of the single clad fiber through the filling resin layer and is converted into heat in the heat sink.

JP 2011-21220 A (released on October 20, 2011) JP 2008-310277 A (released on December 25, 2008)

  However, the above-described conventional configuration simply has a higher refractive index than the cladding of the optical fiber, and leaks residual excitation light from the cladding to the filling resin layer covering the cladding. For this reason, there is a problem that residual excitation light incident on the filling resin layer from the clad tends to concentrate on a part of the filling resin layer, and local deterioration of the filling resin layer occurs. Although it is known as a prior art to use a resin having a low light absorption rate (transparent resin), an optical device having high output residual excitation light because the light absorption rate cannot be reduced to zero. This local light absorption becomes a reliability bottleneck. This problem also applies to the leakage light of the signal light from the core.

  Therefore, the present invention provides an optical device having a configuration in which residual excitation light incident from the optical fiber cladding and leakage light of signal light from the core are difficult to concentrate on a part of the resin layer covering the connection portion between the optical fibers, and the manufacturing thereof. The purpose is to provide a method.

  The optical device of the present invention includes a first optical fiber having a core coated with a clad, a second optical fiber having a core coated with a clad and connected to the first optical fiber at a connection portion, A connection that covers the clad of the first and second optical fibers in the connection portion and the vicinity region thereof, and includes dispersed particulate scatterers that scatter incident light from the connection portion and the vicinity region. And a partial resin layer.

  According to said structure, the connection part resin layer in which the connection part of a 1st optical fiber and a 2nd optical fiber and the cladding in the area | region vicinity contain the particle-like scatterer which scatters incident light are disperse | distributed Covered with

  Here, in the connection part of the 1st optical fiber and the 2nd optical fiber, when the axis gap of the core of the 1st optical fiber and the core of the 2nd optical fiber has arisen, the signal light transmitted in the core A part of the light becomes leaked light and enters the connecting portion resin layer from the core through the clad. Similarly, residual pumping light propagating through the cladding of the first optical fiber (remaining pumping light used to amplify the signal light in the core) also enters the connecting portion resin layer. The leakage light and residual excitation light of the signal light incident on the connection portion resin layer are scattered in the connection portion resin layer due to the presence of a scatterer in the connection portion resin layer.

  As a result, a situation in which residual excitation light or signal light leakage light proceeds while concentrating on a part of the connecting portion resin layer is avoided. As a result, it is possible to prevent the connection portion resin layer from being deteriorated by the residual excitation light and the leakage light of the signal light, and to improve the reliability of the optical device.

  In the above optical device, the connecting portion resin layer may have a refractive index larger than that of the cladding of the first and second optical fibers.

  According to the above configuration, for example, the residual excitation light propagating through the cladding of the first optical fiber has a refractive index of the connecting portion resin layer larger than that of the first and second optical fibers. Incident. The residual excitation light incident on the connection portion resin layer is scattered in the connection portion resin layer due to the presence of a scatterer in the connection portion resin layer. In addition, the leakage light of the signal light from the connection part enters the connection part resin layer through the clad through the core and the residual excitation light, and the scatterer is present in the connection part resin layer. Scatter in the layer.

  As described above, the residual excitation light and the leakage light of the signal light incident on the connection portion resin layer are scattered in a wide range in the connection portion resin layer and do not concentrate on a part of the connection portion resin layer. As a result, it is possible to reliably prevent the connection portion resin layer from being deteriorated by the residual excitation light and the leakage light of the signal light, and to further improve the reliability of the optical device.

  In the above optical device, the connection resin layer has a refractive index smaller than that of the cladding of the first and second optical fibers, and the scatterer is smaller than the cladding of the first and second optical fibers. It is good also as a structure with a large refractive index.

  According to the above configuration, for example, the residual excitation light propagating through the cladding of the first optical fiber has a refractive index of the connection resin layer that is smaller than the refractive index of the cladding of the first and second optical fibers. It is difficult to directly enter the layer. However, since the refractive index of the scatterer is higher than the refractive index of the cladding of the first and second optical fibers, the residual excitation light easily enters the scatterer that is in contact with the outer peripheral surface of the cladding.

  Therefore, the residual excitation light that has reached the connection resin layer enters the scatterer that is in contact with the outer peripheral surface of the clad while propagating through the clad, and is scattered by the scatterer into the connection resin layer.

  In addition, the leakage light of the signal light from the connection part enters the connection part resin layer through the core through the cladding in the same manner as the residual excitation light, and the connection part resin layer has a scatterer in the connection part resin layer. Scatter in the resin layer.

  As a result, the residual excitation light and the leakage light of the signal light are incident on the connection resin layer in a wide range in the axial direction of the first and second optical fibers, and are concentrated on a part of the connection resin layer. Is definitely avoided. As a result, it is possible to reliably prevent the connection portion resin layer from being deteriorated by the residual excitation light and the leakage light of the signal light, and to further improve the reliability of the optical device.

  In the above optical device, the connection portion resin layer includes a first portion provided so as to cover the connection portion, and a side in a direction in which residual excitation light propagates to the first portion. A second portion provided adjacent to the portion, and the second portion may include more scatterers than the first portion.

  The intensity of the residual pumping light incident on the connection resin layer from the first or second optical fiber becomes stronger on the upstream side in the propagation direction of the residual pumping light propagating through the first optical fiber, and weaker on the downstream side in the propagation direction. Become. Therefore, when the content of the scatterer in the connection portion resin layer is uniform, the intensity of the residual excitation light scattered from the scatterer and emitted from the connection portion resin layer becomes stronger on the upstream side in the propagation direction, It becomes weak downstream in the propagation direction. In this way, when the intensity of the residual excitation light emitted from the connection portion resin layer is biased, for example, a part of the heat dissipation member that covers the outer periphery of the connection portion resin layer is locally heated, and the connection portion around the portion There may be a problem that the deterioration of the resin layer is promoted.

  In order to avoid such a problem, in the above configuration, the content of the scatterer in the connecting portion resin layer is decreased on the upstream side in the propagation direction and increased on the upstream side in the propagation direction. ing. In other words, the content of the scatterer in the connection resin is reduced in the first part where the stronger residual excitation light is incident, and is increased in the second part where the weaker residual excitation light is incident.

  Here, the residual excitation light that is incident on the connecting portion resin and propagates in the connecting portion resin has a vector in the upstream to downstream direction. Therefore, in the second part having a higher content of scatterers than in the first part, the ratio of the residual excitation light converted in the vector direction (from upstream to downstream) is increased, and the residual excitation light directed outward is reduced. To increase. For this reason, the intensity | strength deviation of the residual excitation light radiate | emitted from a connection part resin layer becomes small compared with the case where content of the scatterer in a connection part resin layer is uniform. As a result, for example, a part of the heat radiating member covering the outer periphery of the connection portion resin layer is locally heated, and the problem that the deterioration of the connection portion resin layer around the portion is less likely to occur.

  Said optical device is good also as a structure provided with the thermal radiation member which covers at least one part of the outer periphery of the said connection part resin layer, and converts the leakage light of the said residual excitation light and the said signal light into heat.

  According to said structure, the leakage light of the residual excitation light and signal light which reached the heat radiating member from the connection part resin layer is converted into heat by the heat radiating member. In this case, the residual excitation light and the leaked light of the signal light are scattered in the connecting portion resin layer, so that local heat is not generated by being concentrated on a part of the heat dissipation member. Thereby, the local heat_generation | fever of a heat radiating member arises and the situation where the connection part resin layer of the part deteriorates can be prevented.

  The optical device manufacturing method of the present invention includes a step of connecting a first optical fiber whose core is covered with a clad and a second optical fiber whose core is covered with a clad, and the first optical fiber. Covering the clad of the first and second optical fibers at a connection portion between the first optical fiber and the second optical fiber with a connection portion resin layer containing dispersed particulate scatterers that scatter incident light It is characterized by having.

  According to said structure, the clad in the connection part of a 1st optical fiber and a 2nd optical fiber is covered with the connection part resin layer containing the state which disperse | distributed the particulate scatterer which scatters incident light. .

  Therefore, for example, when the residual excitation light propagating through the cladding of the first optical fiber reaches the region where the connection resin layer is provided, the residual excitation light enters the connection resin layer from the cladding. In this case, if the refractive index of the connecting portion resin layer is larger than the refractive index of the cladding, the residual excitation light is directly incident on the connecting portion resin layer, and the refractive index of the connecting portion resin layer is higher than the refractive index of the cladding. If it is smaller, the light enters the connecting portion resin layer through a scatterer in contact with the outer peripheral surface of the clad. The residual excitation light incident on the connection portion resin layer is scattered in the connection portion resin layer due to the presence of the scatterer.

  In addition, in the connection portion, when the axial deviation between the core of the first optical fiber and the core of the second optical fiber occurs, a part of the signal light transmitted through the core becomes leakage light, and the core In the same manner as the residual excitation light, it enters the connecting portion resin layer through the cladding. Similarly to the residual excitation light, the leakage light of the signal light is also scattered in the connection portion resin layer due to the presence of a scatterer in the connection portion resin layer.

  As a result, a situation in which residual excitation light or signal light leakage light proceeds while concentrating on a part of the connecting portion resin layer is avoided. As a result, it is possible to prevent the connection portion resin layer from being deteriorated by the residual excitation light and the leakage light of the signal light, and to improve the reliability of the optical device.

  According to the configuration of the present invention, it is possible to prevent the connection resin layer that covers the connection portions of the first and second optical fibers from being deteriorated due to residual excitation light and signal light leakage light. Can be improved.

FIG. 1A is a longitudinal sectional view showing an optical device according to an embodiment of the present invention. FIG. 1B is a graph showing an outline of the temperature distribution in the optical device shown in FIG. FIG. 2A is a longitudinal sectional view showing an optical device of a comparative example. FIG. 2B is a graph showing an outline of the temperature distribution in the optical device shown in FIG. It is a longitudinal cross-sectional view which shows the optical device of the modification of the optical device shown to (a) of FIG. FIG. 4A is a longitudinal sectional view showing an optical device according to another embodiment of the present invention. FIG. 4B is a graph showing an outline of the temperature distribution in the optical device shown in FIG. It is a longitudinal cross-sectional view which shows the optical device of the modification of the optical device shown in FIG. It is a longitudinal cross-sectional view which shows the optical device of further another embodiment of this invention. It is a longitudinal cross-sectional view which shows the optical device of the modification of the optical device shown in FIG. It is a longitudinal cross-sectional view which shows the optical device of further embodiment of this invention.

[Embodiment 1]
Embodiments of the present invention will be described below with reference to the drawings.

(Configuration of optical device 1)
FIG. 1A is a longitudinal sectional view showing an optical device 1 according to an embodiment of the present invention. FIG. 1B is a graph showing an outline of the temperature distribution in the optical device 1 shown in FIG.

  As shown to (a) of FIG. 1, the optical device 1 is provided with the 1st optical fiber 11 and the 2nd optical fiber 12, and these 1st optical fiber 11 and the 2nd optical fiber 12 are fusion splicing parts ( The connection part) 13 is fusion-spliced.

  The first optical fiber 11 has a core 21 at the center, the core 21 is covered with a clad 22, and the clad 22 is covered with a coating resin layer 23. The refractive index of the cladding 22 is smaller than the refractive index of the core 21, and the refractive index of the coating resin layer 23 is smaller than the refractive index of the cladding 22. The above-described residual excitation light 17 propagates in the cladding 22.

  The second optical fiber 12 has a core 31 in the center, the core 31 is covered with a clad 32, and the clad 32 is covered with a coating resin layer 33. The refractive index of the cladding 32 is smaller than the refractive index of the core 21, and the refractive index of the coating resin layer 23 is larger than the refractive index of the cladding 32.

  In the first and second optical fibers 11 and 12, the coating resin layers 23 and 33 are peeled off at the fusion splicing portion 13 and the vicinity thereof to expose the clads 22 and 33, and these exposed portions are the connecting portion resin layers. 14 is covered. The connecting portion resin layer 14 is a high refractive index resin layer made of a resin having a higher refractive index than the clads 22 and 33.

  Further, the connecting portion resin layer 14 includes a particulate filler (particulate scatterer) 15. In the present embodiment, the refractive index of the filler 15 may be larger or smaller than that of the connecting portion resin layer 14, but it is necessary that it be different from the refractive index of the connecting portion resin layer 14. The filler 15 is formed in a particulate form, and although the material is not particularly limited, it is desirable that the filler 15 be a material having a low absorptance with respect to a wavelength propagating through the core and the clad. For example, quartz, silica, alumina or the like can be used.

  The periphery of the connecting portion resin layer 14 is covered with a heat radiating frame (heat radiating member) 16. The heat dissipating frame 16 is made of a material having good thermal conductivity, for example, metal.

(Operation of optical device 1)
In the above configuration, in the first optical fiber 11, the residual excitation light 17 is a low refractive index resin layer in which the coating resin layer 23 is smaller than the refractive index of the cladding 22, as shown in FIG. Therefore, it is difficult to leak from the coating resin layer 23 and propagates in the cladding 22. Thereafter, the residual excitation light 17 enters the connection portion resin layer 14 mainly from the clad 22 where the coating resin layer 23 of the first optical fiber 11 is interrupted in the region where the connection portion resin layer 14 is provided.

  Next, a part of the residual excitation light 17 incident on the connection portion resin layer 14 is absorbed by the connection portion resin layer 14 and becomes heat. At this time, since the propagation direction of the residual excitation light 17 incident on the connection portion resin layer 14 is randomized by the filler 15, local heat generation due to the concentration of the residual excitation light 17 in a part does not occur. Further, the residual excitation light 17 that has reached the heat radiating frame 16 without being absorbed by the connecting portion resin layer 14 is concentrated on a part of the heat radiating frame 16 and is not converted into heat, so that The first and second optical fibers 11 and 12 are converted into heat in a wide range in the axial direction. As a result, the temperature distribution (solid line) in the heat dissipating frame 16 is flat and spread over a wide range, as shown in FIG. Note that the temperature distribution indicated by a two-dot chain line in FIG. 1B is that of an optical device 101 of a comparative example described later.

  In addition, in the fusion splicing portion 13, when an axial shift occurs between the core 21 of the first optical fiber 11 and the core 31 of the second optical fiber 12, one of the signal lights transmitted through the cores 21 and 31. The portion becomes leaked light and enters the connecting portion resin layer 14 from the cores 21 and 31 through the clads 22 and 32. Similarly to the residual excitation light 17, the leakage light of the signal light is scattered in the connection portion resin layer 14 due to the presence of the filler 15 in the connection portion resin layer 14, and the first and second in the heat dissipation frame 16. It is converted into heat in a wide range in the axial direction of the optical fibers 11 and 12.

  As a result, it is possible to prevent a situation in which the heat dissipation frame 16 generates heat locally and a part of the connecting portion resin layer 14 is deteriorated by the heat, and the reliability of the optical device 1 can be improved.

(Comparative example)
Next, a comparative example for the optical device 1 of the present embodiment will be described. FIG. 2A is a longitudinal sectional view showing an optical device 101 of a comparative example. FIG. 2B is a graph showing an outline of the temperature distribution in the optical device 101 shown in FIG.

  As shown in FIG. 2A, in the optical device 101, as in the optical device 1, the coating resin layers 23 and 33 of the first and second optical fibers 11 and 12 are formed at the fusion splicing portion 13 and the vicinity thereof. The clad 22 and 33 are exposed by peeling off. These exposed portions are covered with a connecting portion resin layer 111 made of a resin having a higher refractive index than the clads 22 and 33. However, the connecting portion resin layer 111 does not include the filler 15.

  In the optical device 101, as in the case of the optical device 1, the residual excitation light 17 that has entered the connection portion resin layer 111 is directly connected to the connection portion resin layer 111 because the connection portion resin layer 111 does not include the filler 15. Proceed inside. For this reason, the residual excitation light 17 is concentrated on a part of the heat dissipation frame 16 and converted into heat. Thereby, the temperature distribution in the heat radiating frame body 16 becomes steep in a part of the heat radiating frame body 16 as shown in FIG. Similarly, the temperature distribution due to the leakage light of the signal light from the fusion splicing portion 13 is also steep in a part of the heat radiating frame 16.

  As a result, the heat dissipation frame 16 generates heat locally, and the heat causes a part of the connecting portion resin layer 14 to deteriorate, and the reliability of the optical device 1 decreases.

  In the present embodiment, the case where the first optical fiber 11 and the second optical fiber 12 are single clad fibers has been described. However, the present invention is not limited to this. That is, the first optical fiber 11 and the second optical fiber 12 may be a single clad fiber, a double clad fiber, a combination of the same kind of clad fibers among double or more clad fibers, or a combination of different kinds of clad fibers. . This also applies to the following embodiments.

(Modification of optical device 1)
FIG. 3 is a longitudinal sectional view showing an optical device 2 which is a modification of the optical device 1 shown in FIG. In the above description, the optical device of the present embodiment is the optical device 1 in which the connecting portion resin layer 14 is covered with the heat dissipation frame 16, but is not limited thereto, as shown in FIG. It is good also as the optical device 2 in which the connection part resin layer 14 is not covered with the thermal radiation frame 16. FIG.

  In the optical device 2, the connection portion resin layer 14 is a high refractive index resin layer made of a resin having a higher refractive index than the clads 22 and 33, and includes the filler 15, as in the optical device 1.

  In the optical device 2, the residual excitation light 17 incident on the connection portion resin layer 14 is scattered in the connection portion resin layer 14 due to the presence of the filler 15. Further, due to the axial displacement of the cores 21 and 31 at the fusion splicing portion 13, the leakage of the signal light incident on the connection portion resin layer 14 from the fusion splicing portion 13 is also present due to the presence of the filler 15. Scatter in layer 14. The residual excitation light 17 scattered in the connecting portion resin layer 14 and the leaked light of the signal light are then emitted into the air.

  Here, when the residual excitation light 17 or the signal light has a high intensity, if the residual excitation light 17 and the leakage light of the signal light incident on the connection resin layer 14 are concentrated on a part of the connection resin layer 14, the connection The partial resin layer 14 is easily heated and deteriorates. However, in the optical device 2, the residual excitation light 17 and the leaked light of the signal light incident on the connection portion resin layer 14 are scattered due to the presence of the filler 15, so that the deterioration of the connection portion resin layer 14 can be prevented. .

[Embodiment 2]
Another embodiment of the present invention will be described below with reference to the drawings.

(Configuration of optical device 41)
FIG. 4A is a longitudinal sectional view showing the optical device 41 according to the embodiment of the present invention. FIG. 4B is a graph showing an outline of the temperature distribution in the optical device 41 shown in FIG.

  As shown to (a) of FIG. 4, the optical device 41 is provided with the connection part resin layer 51 instead of the connection part resin layer 14 of the optical device 1 (refer (a) of FIG. 1). Other configurations are the same as those of the optical device 1.

  The connecting portion resin layer 51 is a low refractive index resin layer made of a resin having a refractive index smaller than that of the clads 22 and 33. The connection resin layer 51 includes a particulate filler (particulate scatterer) 52. The refractive index of the filler 52 is larger than the refractive indexes of the clads 22 and 33. The material of the filler 52 may be the same as that of the filler 15.

(Operation of optical device 41)
In the above configuration, in the first optical fiber 41, the residual excitation light 17 is a low refractive index resin layer in which the coating resin layer 23 is smaller than the refractive index of the cladding 22, as shown in FIG. Therefore, it is difficult to leak from the coating resin layer 23 and propagates in the cladding 22. Thereafter, the residual excitation light 17 reaches the connecting portion resin layer 51.

  Here, although the refractive index of the connecting portion resin layer 51 is smaller than the refractive index of the clads 22 and 33, the refractive index of the filler 52 is larger than the refractive index of the clads 22 and 33. Therefore, although the residual excitation light 17 does not easily enter the connection portion resin layer 51, the residual excitation light 17 enters the filler 52 that is in contact with the outer peripheral surfaces of the claddings 22 and 33.

  As a result, the residual excitation light 17 that has reached the connecting portion resin layer 51 is incident on the filler 52 that is in contact with the outer peripheral surface of the cladding 22, 33 while propagating through the cladding 22, 33. It is scattered in the connection part resin layer 51. Therefore, the residual excitation light 17 incident on the connecting portion resin layer 51 via the filler 52 is concentrated on a part of the heat dissipation frame 16 and is not converted into heat, and the first and second light in the heat dissipation frame 16 It is converted into heat in a wide range in the axial direction of the fibers 11 and 12. As a result, as shown in FIG. 4B, the temperature distribution (solid line) in the heat dissipation frame 16 of the optical device 41 is flatter and wider than the case of the optical device 1 (dashed line). It becomes.

  Similarly to the residual excitation light 17, the clad 22, 33 is also applied to the leakage light of the signal light from the fusion splicing portion 13 that is generated when the core 21 and the core 31 are misaligned in the splicing splicing portion 13. Is incident on the filler 52 that is in contact with the outer peripheral surface of the optical fiber, is scattered by the filler 52, and is converted into heat in a wide range in the axial direction of the first and second optical fibers 11 and 12 in the heat dissipation frame 16.

  As a result, it is possible to more reliably prevent a situation in which the heat dissipation frame 16 generates heat locally and a part of the connecting portion resin layer 51 deteriorates due to the heat, and the reliability of the optical device 41 is further improved. Can do.

(Modification of optical device 41)
FIG. 5 is a longitudinal sectional view showing an optical device 42 which is a modification of the optical device 41 shown in FIG. As shown in FIG. 5, the optical device 42 may be an optical device 42 in which the connecting portion resin layer 51 is not covered with the heat dissipation frame 16, as in the optical device 2.

  In the optical device 42, the residual excitation light 17 that has reached the connecting portion resin layer 51 is incident on the filler 52 that is in contact with the outer peripheral surfaces of the claddings 22 and 33 while propagating through the claddings 22 and 33. It is scattered in the connection part resin layer 51. Further, the leakage light of the signal light generated due to the axial deviation of the cores 21 and 31 at the fusion splicing portion 13 is also incident on the filler 52 in contact with the outer peripheral surfaces of the clads 22 and 33 and is connected by the filler 52. Scattered into the resin layer 51. The residual excitation light 17 and the leaked light of the signal light scattered in the connecting portion resin layer 51 are then emitted into the air.

  Here, since the connection part resin layer 51 is a low refractive index resin layer including the filler 52 in the optical device 42, the connection part resin layer 14 illustrated in FIG. 3 is a high refractive index resin layer including the filler 15. Compared with the optical device 2, it is possible to further promote the scattering of the residual excitation light 17 and the leakage light of the signal light in the connection portion resin layer 51. Thereby, it is possible to prevent the deterioration of the connection portion resin layer 51 due to the concentration of the residual excitation light 17 and the leakage light of the signal light in a part.

[Embodiment 3]
Still another embodiment of the present invention will be described below with reference to the drawings.

(Configuration of optical device 43)
FIG. 6 is a longitudinal sectional view showing the optical device 43 according to the embodiment of the present invention. As shown in FIG. 6, the optical device 43 includes a first resin layer (first portion) 53 and a resin layer (first layer) instead of the connection resin layer 14 of the optical device 1 (see FIG. 1A). 2 part) 54. Other configurations are the same as those of the optical device 1.

  The first resin layer 53 is provided so as to cover the fusion splicing portion 13 and the vicinity thereof, and the second resin layer 54 is disposed on the side of the first resin layer 53 in the direction in which the residual excitation light 17 propagates. 53 is provided adjacent.

  The first and second resin layers 53 and 54 are low refractive index resin layers made of a resin having a smaller refractive index than the clads 22 and 33. The first and second resin layers 53 and 54 include a particulate filler (particulate scatterer) 52, and the second resin layer 54 includes more filler 52 than the first resin layer 53. Yes. The refractive index of the filler 52 is larger than the refractive indexes of the clads 22 and 33. The material of the filler 52 may be the same as that of the filler 15. For example, the content of the filler 52 (% by weight in the connecting portion resin layer) is 10% for the first resin layer 53 and 20% for the second resin layer 54.

(Operation of optical device 43)
In the above configuration, in the first optical fiber 43, the residual excitation light 17 is a low-refractive-index resin layer whose coating resin layer 23 is smaller than the refractive index of the cladding 22, as shown in FIG. Propagates from the layer 23 and propagates in the cladding 22. Thereafter, the residual excitation light 17 reaches the first resin layer 53.

  Here, although the refractive indexes of the first and second resin layers 53 and 54 are smaller than the refractive indexes of the claddings 22 and 33, the refractive index of the filler 52 is larger than the refractive indexes of the claddings 22 and 33. Therefore, although the residual excitation light 17 is difficult to enter the first and second resin layers 53 and 54, the residual excitation light 17 enters the filler 52 that is in contact with the outer peripheral surfaces of the claddings 22 and 33.

  As a result, the residual excitation light 17 that has reached the first resin layer 53 propagates through the portions of the claddings 22 and 33 that are covered by the first and second resin layers 53 and 54, while the outer periphery of the claddings 22 and 33. The light enters the filler 52 in contact with the surface and is scattered by the filler 52 into the first and second resin layers 53 and 54. Therefore, the residual excitation light 17 incident on the first and second resin layers 53 and 54 via the filler 52 is concentrated on a part of the heat dissipation frame 16 and is not converted into heat, and thus the light in the heat dissipation frame 16. It is converted into heat in a wide range in the axial direction of the fibers 11 and 12.

  Here, a part of the residual excitation light 17 enters the first resin layer 53 via the filler 52 of the first resin layer 53, and the remaining part of the residual excitation light 17 passes through the filler 52 of the second resin layer 54. Is incident on. In this case, since the second resin layer 54 contains more filler 52 than the first resin layer 53, the amount of residual excitation light 17 incident on the heat dissipation frame 16 from the first and second resin layers 53 and 54 is Easy to equalize. Thereby, the temperature distribution in the heat dissipation frame 16 of the optical device 43 becomes flatter and wider than the case of the optical device 41 shown in FIG. 4B (solid line).

  Similarly to the residual excitation light 17, the clad 22, 33 is also applied to the leakage light of the signal light from the fusion splicing portion 13 that is generated when the core 21 and the core 31 are misaligned in the splicing splicing portion 13. Is incident on the filler 52 in contact with the outer peripheral surface of the optical fiber 11 and is scattered by the filler 52 and converted into heat in a wide range in the axial direction of the optical fibers 11 and 12 in the heat dissipation frame 16.

  As a result, it is possible to more reliably prevent a situation where the heat radiating frame 16 generates heat locally and a part of the connecting portion resin layer 14 deteriorates due to the heat, thereby further improving the reliability of the optical device 43. Can do.

  In addition, the structure provided with the 1st and 2nd resin layers 53 and 54 of this Embodiment is applicable also to the optical device of other embodiment.

(Modification of optical device 43)
FIG. 7 is a longitudinal sectional view showing an optical device 44 which is a modification of the optical device 43 shown in FIG. As shown in FIG. 7, the optical device 43 may be an optical device 44 in which the first and second resin layers 53 and 54 are not covered with the heat dissipation frame 16, as in the optical device 42.

  In the optical device 44, the residual excitation light 17 that has reached the first resin layer 53 is in contact with the outer peripheral surfaces of the claddings 22 and 33 while propagating through the claddings 22 and 33 covered by the first resin layer 53. The filler 52 is incident on the filler 52 and scattered by the filler 52 into the first and second resin layers 53 and 54. Further, the leakage light of the signal light generated due to the axial deviation of the cores 21 and 31 at the fusion splicing portion 13 is also incident on the filler 52 that is in contact with the outer peripheral surfaces of the claddings 22 and 33, and is Further, the light is scattered in the second resin layers 53 and 54. The residual excitation light 17 and the leaked light of the signal light scattered in the first and second resin layers 53 and 54 are then emitted into the air.

  Here, in the optical device 44, the first resin layer 53 having a relatively small filler 52 content and the second resin layer 54 having a relatively large filler 52 content are adjacent to each other in the direction in which the residual excitation light 17 propagates. Therefore, the amount of residual excitation light 17 emitted from the first and second resin layers 53 and 54 can be made uniform as compared with the optical device 42. Thereby, a part of members arranged around the first and second resin layers 53 and 54 are locally heated, and the heat prevents the first and second resin layers 53 and 54 from being deteriorated. can do.

[Embodiment 4]
Still another embodiment of the present invention will be described below with reference to the drawings.

(Configuration of optical device 45)
FIG. 8 is a longitudinal sectional view showing the optical device 45 according to the embodiment of the present invention. As shown in FIG. 8, the optical device 45 includes a heat radiating member 55 instead of the heat radiating frame 16 of the optical device 41 (see FIG. 4). Other configurations are the same as those of the optical device 41.

  The heat dissipation member 55 provided in the optical device 45 has a structure in which, for example, an upper side portion of the heat dissipation frame 16 is removed and an upper portion of the connection portion resin layer 51 is opened.

  In the first optical fiber 45, the residual excitation light 17 propagates through the cladding 22 without leaking from the coating resin layer 23 because the coating resin layer 23 is a low refractive index resin layer smaller than the refractive index of the cladding 22. . Thereafter, the residual excitation light 17 reaches the connecting portion resin layer 51. The residual excitation light 17 that has reached the connecting portion resin layer 51 enters the filler 52 that is in contact with the outer peripheral surfaces of the claddings 22 and 33 while propagating through the claddings 22 and 33. Scattered into the layer 51.

  A part of the residual excitation light 17 incident on the connecting portion resin layer 51 via the filler 52 is emitted into the air from the upper part where the heat radiating member 55 does not exist, and the rest is converted into heat by the heat radiating member 55. In this case, the residual excitation light 17 is not concentrated on a part of the heat radiating member 55 and converted into heat, but is converted into heat in a wide range in the axial direction of the first and second optical fibers 11 and 12 in the heat radiating member 55. Converted. Thereby, the temperature distribution in the heat dissipation member 55 of the optical device 45 is flat and spread over a wide range.

  Further, in the fusion splicing portion 13, the leakage light of the signal light from the fusion splicing portion 13 that is generated when the core 21 and the core 31 are misaligned is also partially radiated in the same manner as the residual excitation light 17. The light is emitted into the air from the upper portion where the member 55 does not exist, and the remainder is converted into heat by the heat dissipation member 55. As a result, it is possible to more reliably prevent the heat radiation member 55 from locally generating heat and causing a part of the connecting portion resin layer 51 to deteriorate due to the heat.

  Note that the configuration of the present embodiment can be applied not only to the optical device 41 (see FIG. 4) but also to the optical device 1 (see FIG. 1A) and the optical device 43 (see FIG. 6).

  The present invention can be used in an apparatus that connects optical fibers and amplifies signal light by pumping light.

1-2 Optical Device 11 First Optical Fiber 12 Second Optical Fiber 13 Fusion Splicing Portion (Connection Portion)
14 Connection part resin layer 15 Filler (scattering body)
16 Heat dissipation frame (heat dissipation member)
17 Residual excitation light 21 Core 22 Cladding 23 Coating resin layer 31 Core 32 Cladding 33 Coating resin layer
42 to 45 Optical device 51 Connection portion resin layer 52 Filler 53 First resin layer (first portion)
54 Second resin layer (second portion)

Claims (6)

A first optical fiber having a core coated with a cladding;
A second optical fiber having a core coated with a clad and connected to the first optical fiber at a connecting portion;
Covers the clad of the first and second optical fibers in the connection portion and the vicinity region thereof, and includes in a dispersed state a particulate scatterer that scatters incident light from the connection portion and the vicinity region. An optical device comprising a connecting portion resin layer.   The optical device according to claim 1, wherein the connecting portion resin layer has a refractive index larger than that of the clad of the first and second optical fibers.   The connecting portion resin layer has a refractive index smaller than that of the cladding of the first and second optical fibers, and the scatterer has a refractive index larger than that of the cladding of the first and second optical fibers. The optical device according to claim 1.   The connecting portion resin layer is provided adjacent to the first portion on the side of the first portion provided to cover the connecting portion and the direction in which residual excitation light propagates to the first portion. The second part includes a larger amount of the scatterer than the first part. 4. The second part according to claim 1, wherein the second part contains more scatterers than the first part. Optical device.   5. The optical device according to claim 1, further comprising a heat dissipation member that covers at least a part of the outer periphery of the connection portion resin layer. Connecting a first optical fiber whose core is covered with a clad and a second optical fiber whose core is covered with a clad;
A connecting portion including the cladding of the first and second optical fibers in a connecting portion between the first optical fiber and the second optical fiber in a state where particulate scatterers that scatter incident light are dispersed. And a step of covering with a resin layer.

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