JP2007271786A - Optical fiber protection body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a fusion splicing part between double clad fibers or between a double clad fiber and an SMF, to maintain high reliability in the fusion splicing part over a long term, or to protect the terminal end part of the double clad fiber, and to maintain high reliability in the terminal end part over a long term. <P>SOLUTION: A protection body 5 is provided to the fusion splicing part of double clad fibers 4, 6, a protection body 7 is provided to a fusion slicing part between the double clad fiber 6 and a CPF 8 and a protection body 9 is provided to a fusion splicing part between the CPF 8 and the SMF 10. The protection bodies 5, 7 protect the fusion splicing part between the double clad fibers and diffuse heat caused by excitation light leaked from the fusion splicing part to the outside. The protection body 9 protects the fusion splicing part between the CPF 8 and the SMF 10 and diffuses residual excitation light removed from the fusion splicing part to the outside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical fiber protector that protects a fusion splicing part or a terminal part of an optical fiber.

  Conventionally, an optical fiber laser using a double clad fiber has been proposed. This optical fiber laser generally includes a resonator having an amplifying medium in which a rare earth element is added to the core of a double clad fiber, and a pumping light source for introducing pumping light into the amplifying medium. The resonator of this optical fiber laser is formed, for example, by connecting an optical fiber in which an optical fiber Bragg grating (hereinafter referred to as FBG) is formed at both ends of the amplification medium.

  When forming such an optical fiber laser, for example, a double-clad fiber that guides pumping light oscillated from a pumping light source and a double-clad fiber such as an amplifying medium are fused and connected, and a single laser that guides laser light is formed. A mode fiber (hereinafter referred to as “SMF”) and a double clat fiber such as an amplification medium are fusion-spliced. As described above, when the double clad fibers or the double clad fiber and the SMF are fusion-spliced, the covering member at the connection end of the optical fiber is removed to remove the bare fiber (the bare optical fiber not covered by the covering member). Each end of the bare fiber is exposed and fusion-bonded to each other, and then the bare fiber thus fusion-bonded is covered again with a coating member such as a UV curable resin (see, for example, Patent Documents 1 to 3). .

  The double-clad fiber has a core that guides light in a single mode (single-mode core), an inner cladding that covers the outer periphery of the single-mode core, and an outer cladding that covers the outer periphery of the inner cladding. In this case, the refractive index of the inner cladding is lower than that of the single mode core and higher than that of the outer cladding. On the other hand, the SMF is an optical fiber having a single mode core and a clad covering the outer periphery of the single mode core. In this case, the refractive index of the single mode core is higher than that of the clad.

JP 2004-272026 A Japanese Patent Laid-Open No. 2005-4128 JP 2005-129863 A

  By the way, when the double clad fibers are fusion-connected as described above, there is a possibility that a part of the multi-mode excitation light propagating through the double-clad fibers leaks from the fusion-splice portion between the double clad fibers. Thus, the excitation light partially leaked from the fusion splicing portion is absorbed by the covering member covering the fusion splicing portion and converted into heat, thereby thermally deteriorating the covering member. That is, due to the heat generated by the excitation light, the covering member generates heat and deteriorates or breaks. As a result, there is a problem that reliability of the fusion splicing portion is deteriorated.

  The excitation light partially leaked from the fusion splicing portion is high before being introduced into the above-described amplification medium (that is, multimode excitation light before being consumed for excitation of the rare earth element). Has optical power. Accordingly, the optical power of the excitation light partially leaked in this way is not at a level that can be ignored even when the connection loss of the fusion splicing portion is reduced.

  On the other hand, when the double-clad fiber and the SMF are fused and connected as described above, the residual pumping light propagating through the double-clad fiber (that is, pumping light whose optical power is consumed for pumping the rare earth element) is doubled. It propagates through the fusion spliced part between the clad fiber and the SMF. In this case, the residual excitation light propagates through the SMF with the connection end of the fusion splicing portion as a boundary, and sequentially leaks from the SMF. The residual excitation light leaking out from the SMF in this way is sequentially absorbed by the covering member covering the fusion splicing part and converted into heat, almost as in the case of the fusion splicing part between the double clad fibers described above. This covering member is thermally deteriorated. That is, due to the heat generated by the residual excitation light, the covering member generates heat and deteriorates or breaks. As a result, there is a problem that the reliability of the fusion splicing portion deteriorates.

  Further, when a backward pumping type optical fiber laser that introduces pumping light into the amplification medium from the laser light output end side of the resonator having the above-described amplification medium is formed, a double that forms such a backward pumping type optical fiber laser is formed. Residual excitation light leaks from the end of the clad fiber. In this case, the residual excitation light leaking from the terminal portion is sequentially absorbed by the covering member at the terminal portion and converted into heat, and the covering member is thermally deteriorated. That is, due to the heat generated by the residual excitation light, the terminal portion generates heat and deteriorates or breaks, resulting in a problem that reliability of the terminal portion deteriorates.

  The present invention has been made in view of the above circumstances, and protects the fusion-bonded portion between the double-clad fibers or between the double-clad fiber and the SMF and maintains the high reliability of the fusion-bonded portion over a long period of time. Another object of the present invention is to provide an optical fiber protector that can protect the end portion of a double-clad fiber and maintain high reliability of the end portion over a long period of time.

  In order to solve the above-mentioned problems and achieve the object, an optical fiber protector according to claim 1 is an optical fiber protector that protects a fusion spliced portion in which double clad fibers are fusion-connected, An accommodation groove for accommodating the fusion splicing portion and a support groove for supporting the optical fiber coating portion in the vicinity of the fusion splicing portion are formed to convert light leaked from the fusion splicing portion into heat and to transmit the heat to the outside. And a resin member that covers at least the fusion splicing part, fixes the fusion splicing part in the housing groove, and transmits light leaked from the fusion splicing part. It is characterized by.

  An optical fiber protector according to claim 2 is an optical fiber protector that protects a fusion spliced portion in which a double clad fiber and a single mode fiber are fusion spliced, and accommodates the fusion spliced portion. A groove and a support groove that supports the optical fiber coating portion in the vicinity of the fusion splicing portion, and a heat radiating plate that converts light leaked from the fusion splicing portion into heat and dissipates the heat to the outside, and at least And a resin member that covers the fusion splicing portion, fixes the fusion splicing portion in the receiving groove, and transmits light leaked from the fusion splicing portion.

  An optical fiber protector according to claim 3 is an optical fiber protector that protects a terminal portion of a double clad fiber, and supports an accommodation groove that accommodates the terminal portion and an optical fiber coating portion in the vicinity of the terminal portion. And a heat sink that converts light leaked from the end portion into heat and dissipates the heat to the outside, and at least covers the end portion and fixes the end portion in the receiving groove. And a resin member that transmits light leaked from the end portion.

  The optical fiber protector according to claim 4 is characterized in that, in the above invention, the resin member has a refractive index lower than that of the clad of the double clad fiber.

  The optical fiber protector according to claim 5 is characterized in that, in the above invention, the resin member has a higher refractive index than the clad of the double clad fiber.

  An optical fiber protector according to a sixth aspect of the present invention covers the housing groove in which the fusion splicing portion or the terminal portion is accommodated and the support groove in which the optical fiber coating portion is disposed, It further comprises a lid that converts light leaked from the fusion splicing part or the terminal part into heat and dissipates the heat to the outside.

  The optical fiber protector according to claim 7 is characterized in that, in the above invention, the lid fixes the optical fiber covering portion in the support groove.

  The optical fiber protector according to claim 8 is characterized in that, in the above invention, the resin member further covers the optical fiber coating portion and fixes the optical fiber coating portion in the support groove. .

  An optical fiber protector according to a ninth aspect is characterized in that, in the above invention, the resin member is transparent at a wavelength within a range of 910 to 980 nm.

  The optical fiber protector according to claim 10 is characterized in that, in the above-mentioned invention, the receiving groove is formed wider and deeper than the support groove.

  The optical fiber protector according to claim 11 is characterized in that, in the above invention, the support groove is formed in a V shape.

  The optical fiber protector according to claim 12 is characterized in that, in the above invention, the resin member is a UV curable resin.

  According to a thirteenth aspect of the present invention, in the optical fiber protector according to the present invention, the heat sink is formed using a metal member including at least one of aluminum, copper, iron, and nickel. .

  The optical fiber protector according to claim 14 is characterized in that, in the above invention, the lid is formed using a metal member containing at least one of aluminum, copper, iron, and nickel.

  An optical fiber protector according to a fifteenth aspect is an optical fiber protector for protecting a fusion spliced portion in which double clad fibers are fusion-spliced together, and an accommodation groove for accommodating the fusion spliced portion and the fusion splicer. And a support groove for supporting the optical fiber coating portion in the vicinity of the splicing connection portion, and comprising a heat radiating plate that converts light leaked from the splicing connection portion into heat and dissipates the heat to the outside, and at least the fusing The connection portion is substantially sealed and fixed in the housing groove, and light leaked from the fusion connection portion is transmitted to the heat radiating plate.

  According to the present invention, it is possible to reduce the power density in the fusion splicing portion between the double clad fibers, and to maintain the fusion splicing portion at an appropriate temperature, thereby preventing the deterioration of the fusion splicing portion. As a result, it is possible to realize an optical fiber protector that protects the fusion spliced portion between the double clad fibers from external force or the like to prevent the breakage and can maintain the high reliability of the fusion spliced portion over a long period of time. There is an effect.

  Further, according to the present invention, the power density in the fusion spliced portion between the double clad fiber and the SMF can be reduced, and the fusion spliced portion can be maintained at an appropriate temperature, thereby deteriorating the fusion spliced portion. Can be prevented. As a result, an optical fiber protector capable of protecting the fusion spliced portion between the double clad fiber and the SMF from an external force and preventing the damage and maintaining the high reliability of the fusion spliced portion over a long period of time is realized. There is an effect that can be done.

  Furthermore, according to the present invention, the power density at the end portion of the double clad fiber can be reduced, and the end portion can be maintained at an appropriate temperature, whereby deterioration of the end portion can be prevented. As a result, it is possible to realize an optical fiber protector that protects the end portion of the double-clad fiber from external force and the like and prevents its breakage and can maintain the high reliability of the end portion for a long period of time.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Preferred embodiments of an optical fiber protector according to the invention (hereinafter sometimes simply referred to as a protector) will be described in detail below with reference to the accompanying drawings. The embodiment according to the present invention is an example embodying the present invention, and does not limit the technical scope of the present invention.

(Embodiment 1)
FIG. 1 is a schematic diagram illustrating a configuration example of an optical fiber laser using the optical fiber protector according to the first embodiment of the present invention. As shown in FIG. 1, an optical fiber laser 1 includes a pumping light source group 2 that oscillates pumping light, a TFB (Tapered Fiber Bundle) 3 that combines a plurality of pumping lights oscillated by the pumping light source group 2, A double clad fiber 4 that propagates the pumping light combined by the TFB 3 in multimode, a double clad fiber 6 formed with an FBG 6a, and a CPF (Cladding Fiber) that is a double clad fiber that functions as an amplifying medium with rare earth added to the core. Pumped Fiber) 8 and SMF 10 formed with FBG 10a. In this case, the double clad fiber 4 is fusion spliced to one end of the double clad fiber 6, the other end of the double clad fiber 6 is fusion spliced to one end of the CPF 8, and the other end of the CPF 8 is fusion spliced to one end of the SMF 10. The Such an optical fiber laser 1 includes a protector 5 that protects a fusion spliced portion of the double clad fibers 4 and 6, a protector 7 that protects a spliced splice between the double clad fiber 6 and the CPF 8, and a CPF 8. And a protector 9 that protects the fusion spliced portion with the SMF 10.

  The excitation light source group 2 oscillates excitation light that excites the rare earth element added to the CPF 8. Specifically, the excitation light source group 2 includes a plurality of excitation light sources 2a that oscillate using laser light having a predetermined wavelength as excitation light. The excitation light source 2a is realized using a laser diode that oscillates laser light of a predetermined wavelength, and optical fibers 2b that propagate this laser light (that is, excitation light) in multimode are connected to each other. For example, when the optical fiber laser 1 oscillates laser light having a wavelength in the range of 1030 to 1130 nm, the excitation light source 2a oscillates excitation light having a wavelength in the range of 910 to 980 nm. Such a plurality of excitation light sources 2a oscillate laser beams having the same wavelength (for example, 915 nm or 975 nm).

  The TFB 3 functions as an optical multiplexer and multiplexes a plurality of pump lights oscillated by the pump light source group 2 into one optical fiber. Specifically, the TFB 3 is obtained by fusion-connecting the above-described plurality of optical fibers 2b to the double clad fiber 4 with low loss. Such a TFB 3 multiplexes a plurality of pump lights propagating through the plurality of optical fibers 2 b into the double clad fiber 4. In this case, the plurality of pumping lights oscillated by the plurality of pumping light sources 2a are input to the double clad fiber 4 in multimode via the optical fibers 2b and TFB3.

  The double clad fiber 4 has a function of guiding light in a single mode and a function of guiding light in a multimode. Specifically, as shown in FIG. 2, for example, the double clad fiber 4 includes a core 4a that functions as a single mode core, a clad 4b that also functions as a core that guides multimode excitation light, and the core 4a. And a clad 4c that also functions as a covering portion that covers the clad 4b. In this case, the clad 4b is disposed in the radial direction of the core 4a and covers the outer periphery of the core 4a. The clad 4c is disposed in the radial direction of the clad 4b and covers the outer periphery of the clad 4a. The refractive index of the cladding 4b is lower than that of the core 4a and higher than that of the cladding 4c. Such a double-clad fiber 4 guides the pumping light (that is, the pumping light oscillated by the pumping light source group 2) input through the TFB 3 in a multimode, and transmits the multi-mode pumping light to the double-clad fiber 6. To enter.

  The double clad fiber 6 has substantially the same cross-sectional structure as the double clad fiber 4 described above, and an FBG 6a is formed in the core. The FBG 6a periodically changes the refractive index of the core of the double clad fiber 6 along the light traveling direction, thereby reflecting light in a predetermined wavelength band with a high reflectance (for example, a reflectance of 99% or more). . Such a double-clad fiber 6 propagates pump light of a predetermined wavelength input through the above-described double-clad fiber 4 in a multimode, and inputs the multimode pump light to the CPF 8. In this case, the FBG 6a transmits the excitation light having the predetermined wavelength (for example, 915 nm or 975 nm).

  The protector 5 functions as an optical fiber protector that protects the fusion spliced portion between the double clad fibers that are fusion spliced together. Specifically, one end of the double clad fiber 6 is fusion-bonded to the end of the double clad fiber 4 as described above. The protector 5 protects the double-clad fibers 4 and 6 by covering the fusion spliced portion, and prevents the fusion spliced portion from being damaged. Further, the protector 5 converts the multimode excitation light partially leaked from the fusion splicing portion into heat, and externally transfers heat caused by the partially leaked excitation light (leakage excitation light). Dissipate. Accordingly, the protector 5 can reduce the power density of the leaked excitation light and can maintain the fusion spliced portion at an appropriate temperature (that is, a temperature at which deterioration does not proceed). As a result, the protector 5 can prevent deterioration of the fusion splicing portion.

  The CPF 8 functions as an amplification medium for the resonator of the optical fiber laser 1. Specifically, the CPF 8 has substantially the same cross-sectional structure as the above-described double clad fiber 4, and a rare earth element such as yttrium (Yb) is added to the core. Such a CPF 8 guides multimode excitation light input through the double clad fiber 6 and excites the rare earth element of the core to emit fluorescence of a predetermined wavelength. For example, when 915 nm or 975 nm excitation light is input to the CPF 8, the excitation light propagates in a multimode through the inner cladding of the CPF 8 and crosses the core of the CPF 8, so that a rare earth element (for example, Yb ) To the excited state. In this case, fluorescence of 1080 nm is generated. Further, the rare earth element (for example, Yb) added to the core of the CPF 8 can be stimulated emission by inputting light having a predetermined wavelength (for example, 1080 nm) generated in this way. That is, the CPF 8 amplifies light having a predetermined wavelength that repeats reflection between the FBGs 6a and 10a functioning as reflectors forming the resonator of the optical fiber laser 1, and as a result, laser light having a predetermined wavelength (for example, 1080 nm) is amplified. Oscillates.

  The rare earth element added to the core of the CPF 8 is, for example, erbium when the optical fiber laser 1 oscillates laser light in the 1.55 μm band (1530 to 1565 nm), and has a wavelength in the range of 1030 to 1130 nm. It is yttrium when oscillating a laser beam having. The rare earth element may be one containing erbium and yttrium (Er-Yb).

  The protector 7 functions as an optical fiber protector that protects the fusion spliced portion between the double clad fibers that are spliced together. Specifically, the other end of the double clad fiber 6 is fusion-connected to one end (end portion on the pumping light input side) of the CPF 8 as described above. The protective body 7 protects the double-clad fiber 6 and the CPF 8 by covering the fusion-bonded portion, and prevents the fusion-bonded portion from being damaged. Further, the protector 7 converts the multi-mode excitation light partially leaking from the fusion splicing portion into heat, and dissipates heat caused by the leakage excitation light from the fusion splicing portion to the outside. Accordingly, the protector 7 can reduce the power density of the leaked excitation light and can maintain the fusion spliced portion at an appropriate temperature (that is, a temperature at which deterioration does not proceed). As a result, the protective body 7 can prevent the deterioration of the fusion splicing portion.

  The SMF 10 is an optical fiber that guides light (for example, laser light) in a single mode, and includes a single mode core and a clad having a refractive index lower than that of the single mode core. In this case, the cladding is disposed so as to cover the outer periphery of the single mode core. A polymer (covering member) having a higher refractive index than that of the cladding is disposed on the outer periphery of the cladding. An FBG 10a is formed in the core of the SMF 10 as described above. The FBG 10a periodically changes the refractive index of the core of the SMF 10 along the light traveling direction, and thereby reflects light in a predetermined wavelength band with a predetermined refractive index (for example, a refractive index of 90% or less). Such an FBG 10a also functions as an output coupler.

  The protector 9 functions as an optical fiber protector that protects the fusion spliced portion between the double clad fiber and the SMF that are fusion spliced together. Specifically, the other end (the end portion on the laser beam output side) of the CPF 8 is fusion-bonded to one end of the SMF 10 as described above. The protector 9 protects the CPF 8 (that is, a double clad fiber) and the SMF 10 by covering the fusion spliced portion and prevents the fusion spliced portion from being damaged. Further, the protector 9 converts the multi-mode residual excitation light leaking (excluded) from the fusion splicing portion into heat, and dissipates the heat caused by the residual excitation light excluded from the fusion splicing portion to the outside. To do. Thereby, the protector 9 can reduce the power density of the residual excitation light and can maintain the fusion spliced portion at an appropriate temperature (that is, a temperature at which deterioration does not proceed). As a result, the protector 9 can prevent the deterioration of the fusion splicing portion.

  Note that the resonator of the optical fiber laser 1 is formed by the above-described CPF 8 and the FBGs 6 a and 10 a disposed on both sides of the CPF 8. When the multimode pumping light oscillated by the pumping light source group 2 is introduced, the resonator emits light having a predetermined wavelength by the input of the pumping light. The light thus emitted (spontaneously emitted light) is repeatedly reflected between the FBGs 6a and 10a and is amplified by the CPF 8. As a result, such a resonator oscillates laser light having a predetermined wavelength with high output. For example, such a resonator oscillates a 1080 nm laser beam with a high output of 10 to 100 W, for example, when 915 nm or 975 nm excitation light is input to the CPF 8.

  The laser light oscillated by the resonator propagates through the SMF 10 in a single mode while passing through the FBG 10 a and is output from the output end 11. Here, by connecting various devices using laser light, such as a laser marking device, a medical laser knife, or an optical communication device, to the output end 11, the optical fiber laser 1 is connected to the device connected to the output end 11. It functions as a suitable laser light source.

  Next, the configuration of the protectors 5, 7, and 9 according to the first embodiment of the present invention will be described. In the following, the protectors 5 and 7 that protect the fusion spliced portion between the double clad fibers will be described first, and then the protector 9 that protects the spliced splice between the double clad fiber and the SMF will be described.

  FIG. 3 is a perspective view schematically showing a configuration example of the protectors 5 and 7 of the first embodiment for protecting the fusion spliced portion between the double clad fibers. As shown in FIG. 3, the protector 5 includes a heat sink 15 formed with a groove 15a that accommodates the fusion spliced portion C1 of the double clad fibers 4 and 6 and the vicinity thereof, and the fusion spliced connection. A portion C1 and the vicinity thereof are covered, and a transparent resin 16 is provided for fixing them in the groove 15a.

  The heat sink 15 absorbs multimode excitation light (the leakage excitation light described above) partially leaked from the fusion splicing portion C1 of the double clad fibers 4 and 6 accommodated in the groove 15a and converts it into heat. , Heat due to the leaked excitation light is dissipated to the outside. In addition, the metal member which forms this heat sink 15 is a thing with high heat conductivity, for example, is a metal member containing at least one of aluminum, copper, iron, and nickel. One example is stainless steel.

  The groove 15a formed in the heat radiating plate 15 includes, for example, an accommodation groove 15d for accommodating the fusion splicing portion C1 of the double clad fibers 4 and 6, and optical fiber coating portions on both sides located in the vicinity of the fusion splicing portion C1. Support grooves 15b and 15c. Specifically, the support grooves 15b and 15c are formed at the mutually opposing edge portions of the heat radiating plate 15, and when the fusion splicing portion C1 is accommodated in the accommodation groove 15d, both sides of the fusion splicing portion C1 are provided. The optical fiber coating portions are respectively supported. On the other hand, the accommodating groove 15d is formed in the region between the support grooves 15b and 15c inside the edge of the heat radiating plate 15, and accommodates at least the fusion splicing portion C1. In this case, the fusion splicing part C1 is accommodated in a non-contact state with respect to the inner wall of the accommodation groove 15d. The inner wall of the housing groove 15d is desirably colored in a color that easily absorbs light (for example, black). This is because the heat dissipation plate 15 can efficiently absorb, for example, leakage excitation light from the fusion splicing portion C1.

  Note that such a fusion splicing portion C1 between the double clad fibers refers to the entire bare fiber exposed when the splicing is performed. That is, the fusion splicing section C1 includes, for example, both bare fibers exposed by removing the covering member (including the outer clad) when the double clad fibers 4 and 6 are fusion spliced, and both of these bare fibers. Connection end. Moreover, the optical fiber coating | coated part mentioned above says the part which is the vicinity of this bare fiber and was coat | covered with the coating | coated member.

  The transparent resin 16 covers the fusion splicing portion C1 accommodated in the accommodation groove 15d and the optical fiber covering portions respectively disposed in the support grooves 15b and 15c, and fixes the fusion splicing portion C1 in the accommodation groove 15d. And this optical fiber coating | coated part is fixed in the support grooves 15b and 15c. Such a transparent resin 16 is, for example, a UV curable resin, and is a transparent resin that transmits leakage excitation light from the fusion splicing portion C1. That is, the transparent resin 16 is transparent at the wavelength of the laser light oscillated by the above-described excitation light source 2a (for example, a wavelength in the range of 910 to 980 nm). In this case, the transparent resin 16 hardly absorbs the leakage excitation light leaked from the fusion splicing portion C1. Therefore, the transparent resin 16 transmits the leakage excitation light without substantially generating heat and absorbs it by the heat radiating plate 15.

  Further, the transparent resin 16 has a lower refractive index than the clad of the double clad fibers 4 and 6 (for example, the inner clad 4b illustrated in FIG. 2) in the fusion splicing portion C1. Therefore, the excitation light propagating in the multi-mode through the fusion splicing portion C1 of the double clad fibers 4 and 6 does not propagate to the transparent resin 16 having a low refractive index as described above, and is not contained in the clad of the fusion splicing portion C1. Be trapped.

  The protector 7 that protects the fusion splicing portion C1 between the double clad fiber 6 and the CPF 8 is configured in substantially the same manner as the protector 5 described above. That is, as shown in FIG. 3, the protector 7 includes the heat dissipation plate 15 and the transparent resin 16 described above, and instead of the double clad fibers 4 and 6, the double clad fiber 6 and the fusion splicing portion C <b> 1 of the CPF 8 are provided. It is accommodated in the groove 15a. In this case, the transparent resin 16 covers the fusion splicing portion C1 between the double clad fiber 6 and the CPF 8, fixes the fusion splicing portion C1 in the accommodation groove 15d, and each of the vicinity of the fusion splicing portion C1. While covering the optical fiber covering portion, these are fixed in the support grooves 15b and 15c, respectively.

  Next, the heat sink 15 of the protectors 5 and 7 will be described. FIG. 4 is a schematic top view illustrating the top surface of the heat dissipation plate 15 viewed from the direction A1 shown in FIG. FIG. 5 is a schematic side view illustrating the side surface of the heat sink 15 viewed from the direction A2 shown in FIG. FIG. 6 is a schematic side cross-sectional view illustrating a side cross section of the heat dissipation plate 15 viewed from the direction A3 shown in FIG.

  As shown in FIGS. 4 to 6, the above-described support grooves 15 b and 15 c are formed in the opposing edges of the heat sink 15, respectively, and the inner side of the edge of the heat sink 15 and the support grooves 15 b and 15 c. An accommodation groove 15d is formed in the area between them. Specifically, the support grooves 15b and 15c are, for example, V-shaped grooves (see FIG. 5) formed in a V shape, and are slightly larger openings than the optical fiber coating portion in the vicinity of the fusion splicing portion C1. It has a width W1. In this case, the support grooves 15b and 15c are formed so that each bottom portion (that is, each V-shaped bottom side) is aligned on a straight line. By supporting and fixing the optical fiber covering portion in such support grooves 15b and 15c, the heat radiating plate 15 can accommodate the fusion splicing portion C1 in the accommodation groove 15d with almost no slack and bending.

  As shown in FIG. 6, the depth D1 of the support grooves 15b and 15c is such that the optical fiber coating part (for example, the coating part of the double clad fibers 4 and 6) can be accommodated in the support grooves 15b and 15c. Is desirable. The support grooves 15b and 15c having such a depth D1 can support the optical fiber covering portion without protruding from the surface of the heat sink 15. As a result, breakage and deterioration of the optical fiber covering portion fixed in the support grooves 15b and 15c can be prevented.

  On the other hand, the accommodation groove 15d is formed wider and deeper than the above-described support grooves 15b and 15c. Specifically, as shown in FIGS. 4 and 6, the receiving groove 15d has an inner wall having a width W2 larger than the opening width W1 of the support grooves 15b and 15c, and a depth D1 of the support grooves 15b and 15c. It is formed by the bottom face which makes depth D2 large compared with. By forming the fusion splicing portion C1 in the wide and deep bottom receiving groove 15d, the heat radiating plate 15 can be welded to the fusion splicing portion C1 (that is, the The fusion splicing portion C1 can be accommodated in the accommodating groove 15d without contacting the fiber). As a result, when the fusion splicing portion C1 is accommodated in the accommodation groove 15d or after it is accommodated, the fusion splicing portion C1 can be prevented from being damaged and deteriorated.

  Next, the protector 9 that protects the fusion spliced portion between the CPF 8 and the SMF 10 will be described. FIG. 7 is a perspective view schematically showing a configuration example of the protector 9 according to the first embodiment for protecting the fusion spliced portion between the CPF 8 and the SMF 10. As shown in FIG. 7, the protector 9 includes a transparent resin 17 having a high refractive index instead of the transparent resin 16 of the protectors 5 and 7 (see FIG. 3) described above. In this case, the protective body 9 is formed by, for example, replacing the double-clad fibers 4 and 6 with a transparent resin 17 in the fusion-bonded portion C2 between the CPF 8 (that is, the double-clad fiber) and the SMF 10 and the optical fiber coating portion in the vicinity. Secure in 15a. Other configurations are the same as those of the protectors 5 and 7 illustrated in FIG. 3, and the same components are denoted by the same reference numerals.

  The transparent resin 17 covers the fusion splicing portion C2 accommodated in the accommodation groove 15d and the optical fiber covering portions respectively disposed in the support grooves 15b and 15c, and is similar to the transparent resin 16 described above. The connecting portion C2 is fixed in the accommodation groove 15d, and the optical fiber coating portion is fixed in the support grooves 15b and 15c. Such a transparent resin 17 is, for example, a UV curable resin, and is a transparent resin that transmits residual excitation light leaked (excluded) from the fusion splicing portion C2. That is, the transparent resin 17 is transparent at the wavelength of the laser light oscillated by the above-described excitation light source 2a (for example, a wavelength in the range of 910 to 980 nm). In this case, the transparent resin 17 hardly absorbs the residual excitation light leaked from the fusion splicing part C2. Therefore, the transparent resin 17 transmits the residual excitation light without substantially generating heat and absorbs it by the heat radiating plate 15.

  Further, the transparent resin 17 has a higher refractive index than the cladding of the CPF 8 and the SMF 10 in the fusion splicing portion C2. Therefore, the residual excitation light propagating in the multi-mode through the fusion splicing part C2 between the CPF 8 and the SMF 10 propagates from the fusion splicing part C2 (that is, the bare fiber of CPF 8 or SMF 10) to the transparent resin 17 having a high refractive index. As a result, the residual excitation light is excluded from the fusion splicing portion C2 and absorbed by the heat radiating plate 15.

  In addition, the fusion splicing part C2 of such a double clad fiber and SMF means the whole bare fiber exposed at the time of fusion splicing similarly to the above-mentioned fusion splicing part C1. That is, the fusion splicing portion C2 includes both bare fibers exposed by removing the covering member (including the outer clad) when the CPF 8 and the SMF 10 are fusion spliced, and the connection end portions of both the bare fibers. Including.

  Moreover, the heat sink 15 of the protection unit 9 absorbs the residual excitation light excluded from the above-described fusion splicing part C2 and converts it into heat, and dissipates the heat caused by the residual excitation light to the outside. The support grooves 15b and 15c formed in the heat dissipation plate 15 of the protective part 9 are substantially the same as the protective bodies 5 and 7 described above, and the optical fiber coating parts on both sides located in the vicinity of the fusion splicing part C2. Support. Further, the housing groove 15d formed in the heat dissipation plate 15 of the protection portion 9 is provided with the fusion splicing portion C2 in a non-contact state with respect to the inner wall and the bottom surface, as in the case of the protection bodies 5 and 7 described above. Accommodate. That is, the heat radiating plate 15 of the protection unit 9 enjoys substantially the same effect as that of the protection units 5 and 7 described above.

  Next, the heat radiation action of the above-described protectors 5, 7, 9 will be described. FIG. 8 is a schematic cross-sectional view illustrating the heat radiation action of the protectors 5 and 7 that protect the fusion splicing portion C1 between the double clad fibers. FIG. 9 is a schematic cross-sectional view illustrating the heat dissipation action of the protector 9 that protects the fusion splicing portion C2 between the double clad fiber and the SMF.

  As shown in FIG. 8, for example, when multi-mode pumping light propagates from the double-clad fiber 4 to the double-clad fiber 6, the multi-mode pumping light scatters, for example, at the bare fiber connection end in the fusion splicer C1. A part of the multimode excitation light leaks from the bare fiber connection end of the fusion splice C1. The protector 5 converts the leakage excitation light partially leaked from the fusion splicing part C1 of the double clad fibers 4 and 6 into heat, and dissipates this heat to the outside.

  Specifically, the heat radiating plate 15 and the transparent resin 16 are protected from an external force or the like by covering the fusion splicing portion C1 in the housing groove 15d, and prevent the fusion splicing portion C1 from being damaged. Further, the transparent resin 16 confines the multimode excitation light (for example, laser light having a wavelength in the range of 910 to 980 nm) propagating in the fusion splicing portion C1 in both bare fibers, and the fusion splicing portion. Leakage excitation light partially leaked from C1 (specifically, the connection end of both bare fibers) is transmitted. The leaked excitation light transmitted through the transparent resin 16 is absorbed by the heat radiating plate 15 and converted into heat. The heat sink 15 dissipates the heat absorbed in this way to the outside.

  The protector 5 having such a heat radiation plate 15 and the transparent resin 16 can reduce the power density of the leakage excitation light and set the fusion splicing portion C1 at an appropriate temperature (that is, a temperature at which deterioration does not proceed). As a result, deterioration of the fusion splicing portion C1 can be prevented. The protector 7 having the heat radiating plate 15 and the transparent resin 16 protects the fusion splicing portion C1 between the double clad fiber 6 and the CPF 8 from an external force or the like, as in the protector 5 described above. The heat resulting from the leaked excitation light from the incoming connection C1 is dissipated to the outside. That is, the protector 7 enjoys the same effects as the protector 5 described above. The protectors 5 and 7 having such a configuration can protect the fusion splicing portion C1 between the double clad fibers, and can maintain the high reliability of the fusion splicing portion C1 over a long period of time.

  On the other hand, when laser light oscillated by the resonator of the optical fiber laser 1 (for example, laser light having a wavelength in the range of 1030 to 1130 nm) propagates from the CPF 8 to the SMF 10, the fusion connection C2 between the CPF 8 and the SMF 10 is used. The residual excitation light propagates along with the laser light. As shown in FIG. 9, the protector 9 described above excludes the residual excitation light from the fusion splicing portion C2 and converts it into heat, and dissipates the heat resulting from the residual excitation light to the outside.

  Specifically, the heat radiating plate 15 and the transparent resin 17 are protected from an external force or the like by covering the fusion splicer C2 in the accommodation groove 15d, and prevent the fusion splice C2 from being damaged. In addition, the transparent resin 17 excludes the multimode residual excitation light propagating in the fusion splicing portion C2 from the bare fiber (that is, leaks from the fusion splicing portion C2). The residual excitation light excluded from the bare fiber is transmitted. The residual excitation light transmitted through the transparent resin 17 is absorbed by the heat radiating plate 15 and converted to heat. The heat sink 15 dissipates the heat absorbed in this way to the outside.

  The protector 9 having such a heat radiating plate 15 and the transparent resin 17 can reduce the power density of the residual excitation light and set the fusion splicing portion C2 to an appropriate temperature (that is, a temperature at which deterioration does not proceed). As a result, deterioration of the fusion splicing portion C2 can be prevented. The protector 9 having such a configuration can protect the fusion splicing portion C2 between the double clad fiber and the SMF, and can maintain high reliability of the fusion splicing portion C2 over a long period of time.

  For example, as shown in FIG. 10, the fusion splicer C2 is not protected by the protector 9 (no protective body), that is, the bare fiber portion of the splicer splice C2 is covered only by a known covering member. In this state, about 8 minutes after the optical fiber laser 1 started to oscillate the laser beam, the optical fiber was disconnected at the fusion splicing portion C2, and the output of the laser beam was greatly reduced. On the other hand, in the state where the protector 9 protects the fusion splicing part C2 as described above (the state where the protector is present), when 5 hours have passed since the optical fiber laser 1 started to oscillate laser light. Even in such a case, the output of the laser beam was not significantly reduced, and the characteristics of the optical fiber laser 1 were stable. In this case, the optical fiber laser 1 can maintain high reliability over a long period of time.

  As described above, in the first embodiment of the present invention, the fusion splicing portion between the double clad fibers is accommodated in the groove formed in the heat sink, and the fusion splicing portion is covered with the transparent resin. The fusion splicing part is fixed in the groove of the heat radiating plate, and the leakage excitation light partially leaked from the fusion splicing part is transmitted through the transparent resin and absorbed by the heat radiating plate and converted into heat. The heat radiation plate is configured to dissipate heat caused by the leaked excitation light to the outside. For this reason, while being able to reduce the power density of the leakage excitation light in the fusion splicing part of the double clad fibers, the fusion splicing part can be maintained at an appropriate temperature, thereby preventing the deterioration of the fusion splicing part. . As a result, an optical fiber protector capable of protecting the fusion spliced portion between the double clad fibers from an external force or the like to prevent the breakage and maintaining high reliability of the fusion spliced portion over a long period of time. Can do.

  Further, since the refractive index of the transparent resin covering the fusion spliced portion between the double clad fibers is set to be lower than that of the clad of the double clad fiber (specifically, the inner clad), the double clad fiber Multi-mode excitation light propagating through the fusion splicing portion can be confined in the bare fiber (that is, in the clad) of the fusion splicing portion. As a result, it is possible to reduce the loss of excitation light at the fusion splicing portion.

  Further, in the first embodiment of the present invention, the fusion-bonded portion of the double clad fiber and the SMF is accommodated in the groove formed in the heat sink, and the fusion-bonded portion is covered with the transparent resin and is disposed in the groove of the heat sink. The residual excitation light excluded from the fusion splicing portion passes through the transparent resin and is absorbed by the heat radiating plate and converted into heat, and the heat radiating plate absorbs the heat caused by the residual excitation light. It was configured to dissipate to the outside. As a result, the power density of the residual pumping light at the fusion spliced portion between the double clad fiber and the SMF can be reduced, and the fusion spliced portion can be maintained at an appropriate temperature. Can be prevented. As a result, an optical fiber protector capable of protecting the fusion spliced portion between the double clad fiber and the SMF from an external force and preventing the damage and maintaining the high reliability of the fusion spliced portion over a long period of time is realized. can do.

  Further, since the refractive index of the transparent resin covering the fusion spliced portion between the double clad fiber and the SMF is set higher than that of the double clad fiber and the SMF clad, the fusion between the double clad fiber and the SMF is increased. Residual excitation light propagating through the spliced connection can be leaked out (ie excluded) from the bare fiber at the spliced splice. As a result, it is possible to prevent the residual excitation light from propagating to the SMF downstream of the fusion splicing portion.

  Furthermore, by flowing the transparent resin into the groove formed in the heat radiating plate, the fusion spliced portion and the optical fiber covering portion in the vicinity thereof can be covered and fixed in the groove. Compared to the conventional recoating operation in which the coating member is coated again on the fusion spliced portion in accordance with the outer diameter of the optical fiber, the fusion spliced portion can be easily recoated.

  By providing the optical fiber protector according to the first embodiment of the present invention at the fusion spliced portion between the double clad fibers or the spliced splice between the double clad fiber and the SMF, the laser oscillation characteristics can be stabilized over a long period of time. And an optical fiber laser capable of maintaining high reliability for a long time can be realized.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. In the optical fiber protector according to the second embodiment, a lid that covers the support grooves 15b and 15c and the housing groove 15d is further attached to the heat dissipation plate 15 of the optical fiber protector according to the first embodiment described above. Also configured to dissipate heat.

  FIG. 11 is a schematic diagram illustrating a configuration example of an optical fiber laser using the optical fiber protector according to the second embodiment of the present invention. As shown in FIG. 11, this optical fiber laser 20 has a protective body 25 instead of the protective body 5 of the optical fiber laser 1 of the first embodiment described above, and has a protective body 27 instead of the protective body 7. In place of the protector 9, a protector 29 is provided. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  The protector 25 protects the fusion spliced portion of the double clad fibers 4 and 6 in substantially the same manner as the protector 5 according to the first embodiment described above. The protector 27 is the same as that of the first embodiment described above. The fusion spliced portion between the double clad fiber 6 and the CPF 8 is protected in the same manner as the protector 7. On the other hand, the protector 29 protects the fusion spliced portion between the CPF 8 and the SMF 10 in substantially the same manner as the protector 9 according to the first embodiment described above.

  FIG. 12 is a perspective view schematically showing a configuration example of the protectors 25 and 27 of the second embodiment for protecting the fusion spliced portion between the double clad fibers. FIG. 13 is a schematic side cross-sectional view illustrating a side cross-section of the protectors 25 and 27 viewed from the direction A3 shown in FIG. As shown in FIGS. 12 and 13, in the protectors 25 and 27 according to the second embodiment, a lid 18 that covers the support grooves 15 b and 15 c and the accommodation groove 15 d is further attached to the heat radiating plate 15. Other configurations are the same as those of the protectors 5 and 7 according to the first embodiment, and the same components are denoted by the same reference numerals.

  The lid 18 is formed of a metal member containing at least one of aluminum, copper, iron, and nickel, for example. One example is stainless steel. The lid 18 uses the transparent resin 16 to fix the fusion splicing portion C1 between the double clad fibers in the accommodation groove 15d, and to fix the optical fiber covering portion near the fusion splicing portion C1 in the support grooves 15b and 15c. It attaches with respect to the heat sink 15 of a state in the aspect which covers this accommodation groove | channel 15d and support groove | channels 15b and 15c. In this case, the lid 18 is fixed to the heat radiating plate 15 using screws 19, for example, as shown in FIG.

  Such a lid 18 confines the fusion splicing portion C1 and the optical fiber covering portion in the vicinity thereof in the accommodation groove 15d and the support grooves 15b and 15c, respectively, and leaks the leakage excitation light leaked from the fusion splicing portion C1. It absorbs and converts it into heat, and dissipates this heat to the outside. In this case, the heat dissipation plate 15 and the lid 18 in which the fusion splicing portion C1 is confined in the housing groove 15d and the optical fiber covering portion in the vicinity of the fusion splicing portion C1 is confined in the support grooves 15b and 15c are fused. The portion C1 and the optical fiber covering portion in the vicinity thereof and the transparent resin 16 covering them are protected from external force and the like, and the damage is prevented. Further, the lid 18 attached to the heat sink 15 in this way prevents the fusion splicing portion C1 or the transparent resin 16 covering it from peeling off from the housing groove 15d, and the light near the fusion splicing portion C1. The fiber covering portion or the transparent resin 16 covering the fiber covering portion is prevented from peeling off from the support grooves 15b and 15c.

  The surface of the lid 18 on the side facing the housing groove 15d is preferably colored in a color that easily absorbs light (for example, black). This is because the lid 18 can efficiently absorb the leakage excitation light from the fusion splicing portion C1, for example.

  On the other hand, the protector 29 is obtained by further attaching a lid 18 to the heat radiating plate 15 in a state where the fusion splicing portion C2 between the CPF 8 (that is, the double clad fiber) and the SMF 10 is fixed in the groove 15a. FIG. 14 is a schematic side sectional view showing a configuration example of the protector 29 according to the second embodiment for protecting the fusion spliced portion between the double clad fiber and the SMF. As shown in FIG. 14, the protector 29 according to the second embodiment has a lid 18 that covers the support grooves 15 b and 15 c and the accommodation groove 15 d in addition to the heat sink 15 in substantially the same manner as the protectors 25 and 27 described above. It is attached. Other configurations are the same as those of the protector 9 according to the first embodiment, and the same components are denoted by the same reference numerals.

  The lid 18 of the protector 29 uses the transparent resin 17 to fix the fusion splicing part C2 between the CPF 8 and the SMF 10 in the housing groove 15d and to support the optical fiber covering part near the fusion splicing part C2 as the support grooves 15b, It attaches with respect to the heat sink 15 fixed in 15c in the aspect which covers this accommodation groove | channel 15d and support groove | channels 15b and 15c. In this case, the lid 18 of the protector 29 is fixed to the heat radiating plate 15 using, for example, screws 19 in the same manner as the protectors 25 and 27 described above (see FIG. 12).

  The lid 18 of the protector 29 confines the fusion splicing portion C2 and the optical fiber covering portion in the vicinity thereof in the housing groove 15d and the support grooves 15b and 15c, respectively, and also removes the residual excitation excluded from the fusion splicing portion C2. It absorbs light and converts it into heat, and dissipates this heat to the outside. In this case, the heat dissipation plate 15 and the lid 18 in which the fusion splicing portion C2 is confined in the housing groove 15d and the optical fiber covering portion in the vicinity of the fusion splicing portion C2 is confined in the support grooves 15b and 15c are fused. The portion C2 and the optical fiber coating portion in the vicinity thereof and the transparent resin 17 covering them are protected from external force and the like, and damage to these is prevented. Further, the lid 18 attached to the heat sink 15 in this way prevents the fusion splicing portion C2 or the transparent resin 17 covering it from peeling off from the housing groove 15d, and the light near the fusion splicing portion C2. The fiber coating portion or the transparent resin 17 covering the fiber coating portion is prevented from peeling off from the support grooves 15b and 15c.

  Next, the heat radiation action of the above-described protectors 25, 27, and 29 will be described. FIG. 15 is a schematic cross-sectional view illustrating the heat dissipation action of the protective bodies 25 and 27 with lids that protect the fusion splicing portion C1 between the double clad fibers. FIG. 16 is a schematic cross-sectional view illustrating the heat dissipation action of the protective body 29 with a lid that protects the fusion splicing portion C2 between the double clad fiber and the SMF.

  As shown in FIG. 15, when multimode excitation light propagates from the double clad fiber 4 to the double clad fiber 6, the protector 25 partially leaks from the fusion splicing part C <b> 1 of the double clad fibers 4 and 6. The leakage excitation light is converted into heat, and this heat is dissipated to the outside.

  Specifically, leakage excitation light (for example, laser light having a wavelength in the range of 910 to 980 nm) leaked from the fusion splicing portion C1 passes through the transparent resin 16 and reaches the heat radiating plate 15 and the lid 18. In this case, the heat sink 15 absorbs the leaked excitation light and converts it into heat, and dissipates this heat to the outside. Further, the lid 18 absorbs the leaked excitation light and converts it into heat, and dissipates this heat to the outside. The protector 25 including the heat radiating plate 15 and the lid 18 can dissipate more heat than the protector 5 of the first embodiment described above.

  The protector 25 having such a configuration can further reduce the power density of the leakage excitation light, and can maintain the fusion splicer C1 at an appropriate temperature (that is, a temperature at which deterioration does not proceed). Deterioration of the fusion splicing portion C1 can be prevented. In addition, the protector 27 dissipates the heat resulting from the leaked excitation light from the fusion splicing portion C1 between the double clad fiber 6 and the CPF 8 in the same manner as the protector 25 described above. That is, the protector 27 enjoys the same effects as the protector 25 described above. The protectors 25 and 27 having such a configuration can protect the fusion splicing portion C1 between the double clad fibers and can maintain the high reliability of the fusion splicing portion C1 for a longer period of time.

  On the other hand, the protector 29 described above causes the residual pumping light that propagates in the fusion splicer C2 from the fusion splicer C2 when the laser light oscillated by the resonator of the optical fiber laser 20 propagates from the CPF 8 to the SMF 10. It is excluded and converted into heat, and the heat resulting from this residual excitation light is dissipated to the outside.

  Specifically, residual excitation light (for example, laser light having a wavelength in the range of 910 to 980 nm) excluded (leaked) from the fusion splicing portion C2 passes through the transparent resin 17 and reaches the heat radiating plate 15 and the lid 18. . In this case, the heat sink 15 absorbs the residual excitation light and converts it into heat, and dissipates this heat to the outside. Further, the lid 18 absorbs the leaked excitation light and converts it into heat, and dissipates this heat to the outside. The protector 29 including the heat radiating plate 15 and the lid 18 can dissipate more heat than the protector 9 of the first embodiment described above.

  The protector 29 having such a configuration can further reduce the power density of the residual excitation light, and can maintain the fusion splicer C2 at an appropriate temperature (that is, a temperature at which deterioration does not proceed). Deterioration of the fusion splicing part C2 can be prevented. Therefore, the protector 29 can protect the fusion splicing portion C2 between the double clad fiber and the SMF, and can maintain the high reliability of the fusion splicing portion C2 for a longer period of time.

  As described above, in the second embodiment of the present invention, with respect to the heat dissipation plate of the optical fiber protector according to the first embodiment described above, the housing groove in which the fusion splicing portion is accommodated and the vicinity of the fusion splicing portion. A lid is further attached in such a manner as to cover the support groove in a state of supporting the optical fiber coating portion, and this lid dissipates heat due to leakage excitation light or residual excitation light from the fusion splicing portion together with the heat sink. Configured. For this reason, while enjoying the effect of Embodiment 1 mentioned above, the optical fiber protector which further improved heat dissipation is realizable.

  Further, the lid is attached to the heat radiating plate, so that the fusion splicing portion and the optical fiber covering portion in the vicinity thereof are confined in the groove of the heat radiating plate. Therefore, it is possible to protect the fusion splicing part and the optical fiber covering part in the groove and the transparent resin covering them from external force, etc., and to prevent the breakage thereof, and also to prevent the fusion splicing part, the optical fiber covering part, or these Can be prevented from peeling from the groove of the heat sink.

  By providing the optical fiber protector according to the second embodiment of the present invention at the fusion spliced portion between the double clad fibers or the spliced splice between the double clad fiber and the SMF, the laser oscillation characteristics can be stabilized over a long period of time. Thus, an optical fiber laser capable of maintaining high reliability for a longer period can be realized.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. In the third embodiment, a backward pumping type optical fiber laser is constructed in which pumping light is introduced from the laser light output end side of the resonator into the CPF (that is, the amplifying medium of the resonator). The optical fiber protector according to the present invention is provided in the fusion splicing portion.

  FIG. 17 is a schematic diagram illustrating a configuration example of a backward-pumped optical fiber laser using the optical fiber protector according to the third embodiment of the present invention. As shown in FIG. 17, this backward pumping type optical fiber laser 30 includes the pumping light source group 2, the TFB 3, the double clad fiber 4, the double clad fiber 6 formed with the FBG 6a, the protectors 5, 7, 9 and It has CPF8. The optical fiber laser 30 includes an SMF 31, 32, a band pass filter (BPF) 33, a photodiode (PD) 34, a control circuit 35, a double clad fiber 36 that forms an FBG 36a, and a double clad fiber. It further has a protector 37 that protects the fusion splicing portion C1.

  In such an optical fiber laser 30, the TFB 3 melt-connects the other end of the optical fiber 2 b whose one end is connected to each pumping light source 2 a and one end of the SMF 32 to the double clad fiber 4 with low loss. In this case, the other end of the SMF 32 serves as the laser light output end 11 described above. The other end of the double clad fiber 4 is fusion spliced to one end of the double clad fiber 36, the other end of the double clad fiber 36 is fusion spliced to one end of the CPF, and the other end of the CPF 8 is the double clad fiber 6. It is fusion spliced to. Further, the other end of the double clad fiber 6 is fusion-connected to one end of the SMF 31, and the other end of the SMF 31 is connected to the BPF 33. The BPF 33 is connected to the PD 34 via an optical fiber. In this case, the protector 5 protects the fusion splice C1 of the double clad fibers 4 and 36, the protector 7 protects the fusion splice C1 between the CPF 8 and the double clad fiber 6, and the protector 9 is a double clad. The fusion splicing part C2 between the fiber 6 and the SMF 31 is protected. The protector 37 is configured in the same manner as the protectors 5 and 7 described above, and protects the fusion splicing portion C1 between the double clad fiber 36 and the CPF 8. On the other hand, the control circuit 35 is electrically connected to the excitation light source group 2 and the PD 34.

  The resonator of the optical fiber laser 30 is formed by the CPF 8 and the FBGs 6 a and 36 a of the double clad fibers 6 and 36 that are fusion-bonded to both ends of the CPF 8. In this case, the FBG 36a transmits excitation light having a predetermined wavelength (for example, laser light having a wavelength in the range of 910 to 980 nm) oscillated by the excitation light source group 2, and is emitted or amplified by the CPF 8 (for example, 1030). The light having a wavelength in the range of ˜1130 nm is reflected at a predetermined low reflectance (for example, a reflectance of 90% or less). The FBG 36a also functions as an output coupler that outputs laser light having a predetermined wavelength (for example, a wavelength in the range of 1030 to 1130 nm) oscillated by the resonator. On the other hand, as described above, the FBG 6a reflects light having a predetermined wavelength (for example, a wavelength within a range of 1030 to 1130 nm) with a predetermined high reflectance (for example, a reflectance of 99% or more).

  Specifically, a plurality of pump lights oscillated by the pump light source group 2 are combined in the double clad fiber 4 in the TFB 3 and then propagate in the double clad fiber 4 in multimode. Such multimode excitation light sequentially propagates through the double clad fiber 4 and the double clad fiber 36 on which the FBG 36 a is formed, and is introduced into the CPF 8. In this case, the protector 5 confines the multi-mode excitation light in the bare fiber of the fusion splicing portion C1 of the double clad fibers 4 and 36, and also results from leakage excitation light from the fusion splicing portion C1. Dissipate heat to the outside. Further, the protector 37 confines the multimode excitation light in the bare fiber of the fusion splicing portion C1 between the double clad fiber 36 and the CPF 8, and also originates from leakage pumping light from the fusion splicing portion C1. Dissipate heat to the outside.

  The excitation light input to the CPF 8 brings the rare earth element (for example, Yb) added to the core of the CPF 8 into an excited state. In this case, the CPF 8 emits fluorescence having a predetermined wavelength (for example, a wavelength in the range of 1030 to 1130 nm). The light emitted by the CPF 8 is repeatedly reflected between the above-described FBGs 6a and 36a and amplified by the CPF 8. As a result, the resonator of the optical fiber laser 30 oscillates laser light having a predetermined wavelength (for example, a wavelength in the range of 1030 to 1130 nm). In this case, the protector 7 converts the light leaked from the fusion splicing portion C1 between the CPF 8 and the double clad fiber 6 into heat and dissipates this heat to the outside.

  Laser light of a predetermined wavelength oscillated by such a resonator mainly passes through the FBG 36 a, and then propagates through the double clad fibers 36 and 4 sequentially, and is input to the SMF 32 via the TFB 3, and from the output end 11 of the SMF 32. Is output. On the other hand, a part of the laser light having a predetermined wavelength is transmitted through the FBG 6 a, and then propagates through the double clad fiber 6 and the SMF 31 in order to be input to the BPF 33. In this case, the protector 9 excludes the residual pumping light propagating through the double clad fiber 6 together with the laser light having the predetermined wavelength from the fusion splicing part C2 between the double clad fiber 6 and the SMF 31, and the fusion splicing part C2. The residual excitation light excluded from the heat is converted into heat and the heat is dissipated to the outside.

  The BPF 33 transmits laser light having a predetermined wavelength (for example, laser light having a wavelength in the range of 1030 to 1130 nm) oscillated by the resonator of the optical fiber laser 30 and excludes the above-described residual excitation light. The BPF 33 inputs only the laser beam having the predetermined wavelength to the PD 34.

  The PD 34 is for detecting the power (light intensity) of laser light oscillated by the resonator of the optical fiber laser 30. Specifically, the PD 34 receives and photoelectrically converts laser light with a predetermined wavelength input via the BPF 33, and transmits an electrical signal corresponding to the power of the laser light with the predetermined wavelength to the control circuit 35. In this way, the PD 34 detects the power of the laser light having the predetermined wavelength and notifies the control circuit 35 of the detection result of the laser light power.

  The control circuit 35 controls the pumping light output of each pumping light source 2a of the pumping light source group 2 based on the detection result of the laser beam power notified by the PD 34. Specifically, the control circuit 35 is electrically connected to the PD 34 and the plurality of excitation light sources 2 a of the excitation light source group 2. The control circuit 35 receives an electrical signal corresponding to the laser light power detected by the PD 34 from the PD 34, and controls each pump light output of the plurality of pump light sources 2a to be constant based on the electrical signal. By the ALC control (constant output control) of the control circuit 35, the plurality of excitation light sources 2a each output excitation light with a constant output power. As a result, the laser oscillation characteristic of the resonator of the optical fiber laser 30 is stabilized.

  The control circuit 35 can achieve the above-described ALC control even when the protectors 5, 7, 9, and 37 are not used in the optical fiber laser 30. The optical fiber laser 30 may include the protectors 25 and 27 according to the second embodiment described above instead of the protectors 5, 7, and 37, or the second embodiment described above instead of the protector 9. You may provide the protector 29 concerning. In this case, the optical fiber laser 30 provided with the protectors 25, 27, 29 further enjoys the operational effects of the second embodiment described above.

  As described above, in the thirtieth embodiment of the present invention, as in the first embodiment described above, the protectors 5, 7, and 37 are provided in the fusion splicing portion C1 between the double clad fibers, and the double clad Since the protector 9 is provided in the fusion splicing portion C2 between the fiber and the SMF, a backward pumping type optical fiber laser that can enjoy the same effects as those of the first embodiment described above can be realized.

  Further, the power of the laser light oscillated by the resonator of the optical fiber laser is detected, and the pump light output of the pump light source group is controlled to be constant based on the detection result of the laser light power. . Therefore, each pump light output of the pump light source group can be controlled so that the power of the laser light oscillated by the resonator of the optical fiber laser is constant, and the laser oscillation characteristics of the resonator can be stabilized.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, a part of the laser light oscillated to the output end side by the backward pumping type optical fiber laser is extracted, the power of the extracted laser light is detected, and the laser light power is detected. Based on the result, the excitation light output of the excitation light source group is controlled to be constant. Further, an optical fiber protector that protects the terminal end portion is further provided at the terminal end portion of the backward pumping type optical fiber laser.

  FIG. 18 is a schematic diagram illustrating a configuration example of a backward-pumped optical fiber laser using the optical fiber protector according to the fourth embodiment of the present invention. As shown in FIG. 18, this backward pumping type optical fiber laser 40 has the end portion of the double clad fiber 6 fused to the SMF 31 in the optical fiber laser 30 of the third embodiment described above as a termination portion, The BPF 33 is connected to the end of the remaining optical fiber 42 connected to the double clad fiber 4 by the TFB 3, and the PD 34 is connected to the BPF 33 through the optical fiber. In this case, the optical fiber laser 40 is provided with a protective body 41 at the end portion of the double clad fiber 6 instead of the protective body 9 of the optical fiber laser 30 of the third embodiment described above. Other configurations are the same as those of the third embodiment, and the same components are denoted by the same reference numerals.

  The TFB 3 of the optical fiber laser 40 has one end connected to the other end of the plurality of optical fibers 2b whose one ends are connected to the plurality of pumping light sources 2a, the other end of the SMF 32 that forms the output end 11 described above, and one end to the BPF 33. The other end of the optical fiber 42 is fused and connected to the double clad fiber 4 with low loss. The TFB 3 demultiplexes a part of laser light having a predetermined wavelength oscillated by the resonator of the optical fiber laser 40 to the optical fiber 42. In this case, the BPF 33 excludes residual excitation light and the like, and inputs only laser light having a predetermined wavelength extracted in the TFB 3 to the PD 34.

  Next, an optical fiber protector according to Embodiment 4 of the present invention will be described. The optical fiber protector (that is, the protector 41) according to the fourth embodiment protects the end portion of the optical fiber laser 40. Specifically, the protector 41 is provided at the end of the double clad fiber 6 that forms the end of the optical fiber laser 40, and protects the end of the double clad fiber 6.

  FIG. 19 is a schematic side sectional view showing a configuration example of the protector 41 that protects the end portion of the double clad fiber 6. As shown in FIG. 19, the protector 41 includes a heat radiating plate 45 formed with a groove 45a for accommodating the terminal end E1 of the double clad fiber 6 and an optical fiber covering portion in the vicinity thereof, and the above-described high refractive index transparent resin. 17 and a lid 46 covering the groove 45a. The end portion E1 of the double clad fiber 6 is a bare fiber portion exposed by removing a covering member (including the outer clad of the double clad structure).

  The heat radiating plate 45 absorbs the residual excitation light leaked (excluded) from the terminal end E1 accommodated in the groove 45a and converts it into heat, and dissipates the heat caused by the residual excitation light to the outside. In addition, the metal member which forms this heat sink 45 is a thing with high heat conductivity, for example, is a metal member containing at least one of aluminum, copper, iron, and nickel. One example is stainless steel.

  The groove 45a formed in the heat radiating plate 45 includes an accommodation groove 45c that accommodates the end portion E1, and a support groove 45b that supports the optical fiber coating portion located in the vicinity of the end portion E1. Specifically, the support groove 45b is formed at the edge of the heat radiating plate 45, and supports the optical fiber coating portion in the vicinity of the terminal end E1 when the terminal end E1 is stored in the storage groove 45c. The support groove 45b is formed in, for example, a V shape like the support grooves 15b and 15c formed in the heat dissipation plate 15, and is larger than the outer diameter of the optical fiber coating portion of the double clad fiber 6. The opening width W1 is slightly large, and the depth D1 is such that the optical fiber coating portion of the double clad fiber 6 can be accommodated in the groove.

  On the other hand, the accommodation groove 45c is formed in the inner region of the edge of the heat radiating plate 45 and accommodates at least the terminal end E1. Such a housing groove 45c has a bottom depth (depth D2) and a width wider than that of the support groove 45b in substantially the same manner as the relationship between the support grooves 15b and 15c formed in the heat dissipation plate 15 and the housing groove 15d. (Width W2). In this case, the terminal end E1 can be accommodated without contacting the inner wall of the accommodation groove 45c. Note that the inner wall of the accommodation groove 45c is preferably colored in a color that easily absorbs light (for example, black). This is because the heat radiating plate 45 can efficiently absorb the residual excitation light from the terminal end E1.

  Here, the transparent resin 17 of the protector 41 covers the end portion E1 housed in the housing groove 45c and the optical fiber coating portion disposed in the support groove 45b, and the end portion E1 is placed in the housing groove 45c. And fixing the optical fiber coating portion in the support groove 45b. Further, the transparent resin 17 has a higher refractive index than the clad (inner clad) of the double clad fiber 6 at the terminal end E1. Therefore, the residual excitation light propagating through the terminal end E1 propagates from the terminal end E1 (that is, the bare fiber portion of the double clad fiber 6) to the transparent resin 17 having a high refractive index. As a result, the residual excitation light is excluded from the terminal end E1 and absorbed by the heat radiating plate 45 and the lid 46.

  The lid 46 is formed of a metal member including at least one of aluminum, copper, iron, and nickel, for example. One example is stainless steel. The lid 46 uses the transparent resin 17 to fix the terminal end E1 in the receiving groove 45c, and to the heat sink 45 in a state where the optical fiber coating portion near the terminal end E1 is fixed in the support groove 45b. It is attached in such a manner as to cover 45c and the support groove 45b. In this case, the lid 46 is fixed to the heat radiating plate 45 using screws, for example, in the same manner as the lid 18 attached to the heat radiating plate 15 described above.

  Such a lid 46 confines the end portion E1 and the optical fiber coating portion in the vicinity thereof in the accommodation groove 45c and the support groove 45b, and absorbs residual excitation light excluded from the end portion E1 and converts it into heat. And dissipate this heat to the outside. In this case, the heat radiating plate 45 and the lid 46 that confine the terminal end E1 in the accommodation groove 45c and confine the optical fiber covering part in the vicinity of the terminal end E1 in the support groove 45b include the optical fiber covering in the terminal end E1 and the vicinity thereof. The portion and the transparent resin 17 covering them are protected from external force and the like, and their breakage is prevented. Further, the lid 46 attached to the heat radiating plate 45 in this way prevents the end portion E1 or the transparent resin 17 covering the end portion E1 from being peeled off from the housing groove 45c, and the optical fiber covering portion in the vicinity of the end portion E1 or The transparent resin 17 covering this is prevented from peeling off from the support groove 45b.

  Note that the surface of the lid 46 on the side facing the accommodation groove 45c is preferably colored in a color that easily absorbs light (for example, black). This is because the lid 46 can efficiently absorb the residual excitation light excluded from the terminal end E1.

  Next, the heat radiation action of the protector 41 that protects the terminal end E1 will be described. FIG. 20 is a schematic cross-sectional view illustrating the heat radiation action of the protector 41 that protects the terminal end E1 of the double clad fiber. Residual pumping light enters the terminal end E1 of the double clad fiber 6 from the resonator side of the optical fiber laser 40, and the residual pumping light propagates through the terminal end E1 and is discharged. In this case, as shown in FIG. 20, the protector 41 excludes the residual pumping light propagating in the terminal end E1 from the terminal end E1 and converts it into heat, and dissipates the heat caused by the residual pumping light to the outside. To do.

  Specifically, residual excitation light (for example, laser light having a wavelength in the range of 910 to 980 nm) excluded (leaked) from the terminal end E1 passes through the transparent resin 17 and reaches the heat radiating plate 45 and the lid 46. In this case, the heat radiating plate 45 absorbs the residual excitation light and converts it into heat, and dissipates this heat to the outside. Further, the lid 46 absorbs the leaked excitation light and converts it into heat, and dissipates this heat to the outside. The protector 41 provided with the heat radiating plate 45 and the lid 46 can dissipate more heat than the case without the lid 46, and dissipates the heat caused by the residual excitation light leaking from the terminal end E1. It has sufficient heat dissipation characteristics.

  The protector 41 having such a configuration can reduce the power density of the residual excitation light at the terminal end E1, and can maintain the terminal end E1 at an appropriate temperature (that is, a temperature at which deterioration does not proceed). As a result, it is possible to prevent the end portion E1 from deteriorating. Therefore, the protector 41 can protect the terminal end E1 of the double clad fiber and maintain the high reliability of the terminal end E1 over a long period of time.

  The control circuit 35 of the optical fiber laser 40 can achieve the above-described ALC control even when the protectors 5, 7, 9, 37, and 41 are not used in the optical fiber laser 40. . The optical fiber laser 40 may include the protectors 25 and 27 according to the second embodiment described above instead of the protectors 5, 7, and 37, or the second embodiment described above instead of the protector 9. You may provide the protector 29 concerning. In this case, the optical fiber laser 30 provided with the protectors 25, 27, 29 further enjoys the operational effects of the second embodiment described above. Further, the protector 41 according to the fourth embodiment does not need to include the lid 46. However, in order to enhance the protection capability and the heat radiation characteristics of the terminal end E1, the structure including the lid 46 is used as described above. It is desirable to do.

  As described above, in the fourth embodiment of the present invention, the terminal portion of the double clad fiber is accommodated in the groove formed in the heat radiating plate, the terminal portion is covered with the transparent resin, and the terminal portion is covered with the heat radiating plate. The residual excitation light excluded from the end portion is transmitted through the transparent resin and absorbed by the heat radiating plate and converted into heat, and the heat resulting from the residual excitation light is radiated from the heat radiating plate. Was configured to dissipate to the outside. For this reason, while being able to reduce the power density of the residual excitation light in the termination | terminus part of a double clad fiber, this termination | terminus part can be maintained at appropriate temperature, and this can prevent degradation of this termination | terminus part. As a result, it is possible to realize an optical fiber protector that protects the end portion of the double-clad fiber from external force or the like and prevents breakage thereof, and can maintain high reliability of the end portion for a long period of time.

  In addition, a lid is further attached to the heat sink of the optical fiber protector so as to cover the housing groove that accommodates the end portion and the support groove that supports the optical fiber covering portion in the vicinity of the end portion. The plate was configured to dissipate the heat caused by the residual excitation light from the end portion together with the plate. For this reason, the heat dissipation of the optical fiber protector that protects the terminal portion can be further enhanced.

  Further, the lid is attached to the heat radiating plate so that the terminal portion and the optical fiber coating portion in the vicinity thereof are confined in the groove of the heat radiating plate. Therefore, the end portion in the groove and the optical fiber covering portion and the transparent resin covering them can be protected from external force and the like, and can be prevented from being damaged, and the end portion, the optical fiber covering portion, or the transparent resin covering them. Can be prevented from peeling from the groove of the heat sink.

  In addition, since the refractive index of the transparent resin covering the end portion of the double clad fiber is set to be higher than that of the clad of the double clad fiber, the residual excitation light propagating through the end portion of the double clad fiber is stopped at this end. Can be efficiently excluded from the bare fiber.

  Further, the optical fiber laser 30 has substantially the same configuration as that of the above-described third embodiment, and further includes an optical fiber protector (for example, a protector 41) that protects the terminal portion of the double clad fiber. Therefore, it is possible to realize a backward pumping type optical fiber laser that can enjoy the same operational effects as those of the third embodiment and can maintain the high reliability of the terminal portion for a long period of time.

  In the first to fourth embodiments of the present invention, the support groove formed on the heat sink is V-shaped. However, the present invention is not limited to this, and the U-shaped or other optical fiber coating portion is configured to be easily supported. Also good. Further, as shown in FIG. 21, the shape of the support groove (for example, the support groove 15b described above) formed in the heat radiating plate is set so that the opening width W3 is equal to that of the optical fiber coating portion (for example, the optical fiber coating portion of the double clad fiber 4). It may be narrower than the outer diameter, and the width W4 in the groove may be wider than the outer diameter of the optical fiber coating portion. For example, the optical fiber coating portion of the double clad fiber 4 can be fitted into the support groove having such a shape, and as a result, the optical fiber coating portion can be fixed in the support groove without being covered with the transparent resin. Can do.

  Further, in the second to fourth embodiments of the present invention, by introducing transparent resin into the housing groove and the support groove of the heat sink, the fusion splicing part or the terminal part and the optical fiber coating part in the vicinity thereof are connected to this. Although these are covered with a transparent resin and fixed in the accommodation groove and the support groove, respectively, the transparent resin covers at least the fusion-bonding portion or the terminal portion, and the fusion-connection portion or What is necessary is just to fix a termination | terminus part in an accommodation groove | channel. In this case, the optical fiber covering portion in the vicinity of the fusion splicing portion or the end portion may not be covered with the transparent resin, and may be pressed and fixed in the support groove by a lid attached to the heat radiating plate.

  Furthermore, in the first to fourth embodiments of the present invention, the optical fiber protector is used for the Fabry-Perot type optical fiber laser including the resonator formed by the amplification medium using CPF and the FBGs on both sides thereof. However, the present invention is not limited to this, and the optical fiber protector according to the present invention can be used for a ring-type optical fiber laser. That is, the optical fiber protector according to the present invention is provided at the fusion splicing part between the double clad fibers in the ring type optical fiber laser, the fusion splicing part between the double clad fiber and the SMF, or the terminal part of the double clad fiber. May be.

  In the first to fourth embodiments of the present invention, the present invention is applied to a fusion splicing portion between double clad fibers in an optical fiber laser, a fusion splicing portion between a double clad fiber and an SMF, or a termination portion of a double clad fiber. However, the present invention is not limited to this, and the optical fiber protector according to the present invention can be used in a laser light amplifying apparatus using a double clad fiber. That is, the optical fiber protector according to the present invention is provided at the fusion splicing part between the double clad fibers, the fusion splicing part between the double clad fiber and the SMF, or the terminal end part of the double clad fiber in the laser light amplifying apparatus. Also good. In this case, it is possible to realize a laser light amplifying apparatus that can stably amplify the laser light for a long time and maintain high reliability for a long time.

  Moreover, in Embodiment 1-4 of this invention, in the optical fiber protector of this invention which protects the fusion splicing part of double clad fibers, a double clad fiber is used as transparent resin which covers a fusion splicing part and its vicinity. Although a transparent resin having a lower refractive index than that of the clad was used, the optical fiber protection according to the present invention can be obtained by replacing the transparent resin with a medium having the same refractive index relationship or by making a substantially vacuum. The body can be realized. That is, the optical fiber protector of the present invention is substantially hermetically fixed in the housing groove so as to cover at least the fusion spliced portion, and the substantially sealed protector container is compared with the clad of the double clad fiber instead of the transparent resin. Then, the gas may be filled with a gas having a low refractive index, or light leaked from the fusion splicing portion may be transmitted to the heat radiating plate as a substantially vacuum. Even in this case, the fusion-spliced portion between the double-clad fibers is protected from external force to prevent the damage, and the excitation light propagating in the multi-mode through the fusion-spliced portion is transmitted in the clad of the fusion-spliced portion. The optical fiber protector according to the present invention can be realized.

It is a schematic diagram which shows one structural example of the optical fiber laser using the optical fiber protector concerning Embodiment 1 of this invention. It is a cross-sectional schematic diagram which illustrates the cross section of a double clad fiber. It is a perspective view which shows typically the example of 1 structure of the optical fiber protector of Embodiment 1 which protects the fusion splicing part of double clad fibers. FIG. 4 is a top schematic view illustrating the upper surface of the heat sink as viewed from the direction A1 shown in FIG. It is a side surface schematic diagram which illustrates the side surface of the heat sink seen from direction A2 shown in FIG. FIG. 4 is a schematic side cross-sectional view illustrating a side cross section of the heat sink viewed from a direction A3 shown in FIG. 3. It is a perspective view which shows typically one structural example of the optical fiber protector of Embodiment 1 which protects the fusion splicing part of CPF and SMF. It is a cross-sectional schematic diagram explaining the thermal radiation effect | action of the optical fiber protector which protects the fusion splicing part of double clad fibers. It is a cross-sectional schematic diagram explaining the heat dissipation effect | action of the optical fiber protector which protects the fusion splicing part of a double clad fiber and SMF. It is a schematic diagram which illustrates the result of the reliability test of the fusion splicing part of a double clad fiber and SMF. It is a schematic diagram which shows one structural example of the optical fiber laser using the optical fiber protector concerning Embodiment 2 of this invention. It is a perspective view which shows typically one structural example of the optical fiber protector of Embodiment 2 which protects the fusion splicing part of double clad fibers. It is a side cross-sectional schematic diagram which illustrates the side cross section of the optical fiber protector seen from direction A3 shown in FIG. It is a side cross-sectional schematic diagram which shows one structural example of the optical fiber protector of Embodiment 2 which protects the fusion splicing part of a double clad fiber and SMF. It is a cross-sectional schematic diagram explaining the heat dissipation effect | action of the optical fiber protector with a lid | cover which protects the fusion splicing part of double clad fibers. It is a cross-sectional schematic diagram explaining the heat dissipation effect | action of the optical fiber protector with a lid | cover which protects the fusion splicing part of a double clad fiber and SMF. It is a schematic diagram which shows one structural example of the back pumping type optical fiber laser using the optical fiber protector concerning Embodiment 3 of this invention. It is a schematic diagram which shows one structural example of the back pumping type | mold optical fiber laser using the optical fiber protector concerning Embodiment 4 of this invention. It is a side cross-sectional schematic diagram which shows one structural example of the optical fiber protector which protects the termination | terminus part of a double clad fiber. It is a cross-sectional schematic diagram explaining the thermal radiation effect | action of the optical fiber protector which protects the termination | terminus part of a double clad fiber. It is a schematic diagram which illustrates another aspect of the support groove formed in the heat sink.

Explanation of symbols

1, 20, 30 Optical fiber laser 2 Excitation light source group 2a Excitation light source 2b, 42 Optical fiber 3 TFB
4, 6, 36 Double clad fiber 4a Core 4b, 4c Clad 5, 7, 9, 25, 27, 29, 37, 41 Protector 6a, 10a, 36a FBG
8 CPF
10, 31, 32 SMF
11 Output end 15, 45 Heat sink 15a Groove 15b, 15c, 45b Support groove 15d, 45c Housing groove 16, 17 Transparent resin 18, 46 Lid 19 Screw 33 BPF
34 PD
35 Control circuit C1, C2 Fusion splicer E1 Terminator

Claims (15)

An optical fiber protector that protects a fusion spliced portion in which double clad fibers are spliced together,
An accommodation groove that accommodates the fusion splicing part and a support groove that supports the optical fiber coating part in the vicinity of the fusion splicing part are formed, and converts light leaked from the fusion splicing part into heat and A heat sink that diffuses outside,
A resin member that covers at least the fusion splicing portion and fixes the fusion splicing portion in the accommodation groove, and transmits light leaked from the fusion splicing portion;
An optical fiber protector comprising: An optical fiber protector that protects a fusion spliced portion obtained by fusion-bonding a double clad fiber and a single mode fiber,
An accommodation groove that accommodates the fusion splicing part and a support groove that supports the optical fiber coating part in the vicinity of the fusion splicing part are formed, and converts light leaked from the fusion splicing part into heat and A heat sink that diffuses outside,
A resin member that covers at least the fusion splicing portion and fixes the fusion splicing portion in the accommodation groove, and transmits light leaked from the fusion splicing portion;
An optical fiber protector comprising: An optical fiber protector for protecting the end of a double clad fiber,
A heat radiating plate formed with a housing groove for housing the terminal portion and a support groove for supporting the optical fiber coating portion in the vicinity of the terminal portion, which converts light leaked from the terminal portion into heat and dissipates the heat to the outside. When,
A resin member that covers at least the terminal portion and fixes the terminal portion in the housing groove, and transmits light leaked from the terminal portion;
An optical fiber protector comprising:   The optical fiber protector according to claim 1, wherein the resin member has a refractive index lower than that of the clad of the double clad fiber.   The optical fiber protector according to claim 2 or 3, wherein the resin member has a refractive index higher than that of the clad of the double clad fiber.   Covering the accommodation groove accommodating the fusion splicing part or the terminal end part and the support groove arranging the optical fiber coating part, and converting light leaked from the fusion splicing part or the terminal end part into heat The optical fiber protector according to claim 1, further comprising a lid that dissipates the heat to the outside.   The optical fiber protector according to claim 6, wherein the lid fixes the optical fiber covering portion in the support groove.   The optical fiber protector according to any one of claims 1 to 6, wherein the resin member further covers the optical fiber coating portion and fixes the optical fiber coating portion in the support groove.   The optical fiber protector according to any one of claims 1 to 8, wherein the resin member is transparent at a wavelength within a range of 910 to 980 nm.   The optical fiber protector according to claim 1, wherein the housing groove is formed wider and deeper than the support groove.   The optical fiber protector according to any one of claims 1 to 10, wherein the support groove is formed in a V shape.   The optical fiber protector according to claim 1, wherein the resin member is a UV curable resin.   The optical fiber protector according to any one of claims 1 to 12, wherein the heat sink is formed using a metal member including at least one of aluminum, copper, iron, and nickel.   The optical fiber protector according to any one of claims 6 to 13, wherein the lid is formed using a metal member containing at least one of aluminum, copper, iron, and nickel. An optical fiber protector that protects a fusion spliced portion in which double clad fibers are spliced together,
An accommodation groove for accommodating the fusion splicing portion and a support groove for supporting the optical fiber coating portion in the vicinity of the fusion splicing portion are formed to convert light leaked from the fusion splicing portion into heat and It has a heat sink that diffuses outside,
An optical fiber protector, wherein at least the fusion splicing part is substantially sealed and fixed in the housing groove, and light leaked from the fusion splicing part is transmitted to the heat radiating plate.

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