Fiber holding structure and laser module

Abstract

Provided is a fiber retention structure that can suppress production of heat by light not coupled to an optical fiber. A fiber retention structure 30 comprises: an optical fiber 20 that includes a front end 21, a first fixing part 22 that is positioned behind the front end 21, and an intermediate part 23 that is positioned between the front end 21 and the first fixing part 22; a ferrule 40 that has formed therein a fiber retention hole 41 that retains the first fixing part 22 of the optical fiber 20; an adhesive material 60 that fixes the first fixing part 22 of the optical fiber 20 in the fiber retention hole 41 of the ferrule 40; and a protection member 50 that covers the ferrule 40. The protection member 50 includes: a support part 51 that covers the circumference of the ferrule 40; and a shielding part 52 that covers a front surface 40A of the ferrule 40 and has formed therein a fiber insertion hole 53 into which the intermediate part 23 of the optical fiber 20 is inserted.

Description

[Technical Field]

[0001] The present invention relates to a fiber holding structure and a laser module, and more particularly to a fiber holding structure that holds an optical fiber to which laser light emitted from a laser element is coupled. [Background technology]

[0002] In general, in a laser module, an optical fiber is inserted into a fiber-holding hole of a ferrule and fixed with an adhesive, and laser light emitted from a laser element is focused onto the end of the optical fiber (see, for example, Patent Document 1). Part of the adhesive that fixes the optical fiber to the ferrule often overflows from the fiber-holding hole of the ferrule and hardens around it. However, with the recent trend toward higher laser output, high-power-density laser light that is not coupled to the optical fiber may enter the adhesive around the fiber-holding hole during alignment of the laser light or during operation of the laser module. Such high-power-density laser light may be absorbed by the adhesive, causing the adhesive to heat up and burn out the optical fiber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-155791 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the problems of the prior art, and aims to provide a fiber holding structure and a laser module that can suppress heat generation due to light that is not coupled to the optical fiber. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a fiber holding structure capable of suppressing heat generation due to light not coupled to an optical fiber. That is, the fiber holding structure of aspect 1 of the present invention includes an optical fiber including a front end, a first fixing portion located rearward of the front end, and an intermediate portion located between the front end and the first fixing portion, a ferrule having a fiber holding hole for holding the first fixing portion of the optical fiber, an adhesive for fixing the first fixing portion of the optical fiber to the fiber holding hole of the ferrule, and a protective member for covering the ferrule. The protective member includes a support portion for covering the periphery of the ferrule, and a shield portion for covering the front surface of the ferrule and having a fiber insertion hole into which the intermediate portion of the optical fiber is inserted.

[0006] Also The fiber holding structure further includes a flange for holding a second fixing portion of the optical fiber located rearward of the first fixing portion, and the support portion of the protection member is fixed to the flange. The flange is attached to the side wall of the laser module.

[0007] Aspects of the present invention 2 In the fiber holding structure of the first aspect, a highly reflective coating layer having a high reflectance for light coupled to the front end of the optical fiber is formed on the front surface of the shielding portion of the protective member.

[0008] Aspects of the present invention 3 is the above-mentioned aspect 1 or 2 In the fiber holding structure, the protective member is made of a material having a higher thermal conductivity than the optical fiber.

[0009] Aspects of the present invention 4 From the above aspect 1 3 In any one of the fiber holding structures of 1 to 4, the fiber holding structure further includes a cooling member having a thermal conductivity higher than that of the optical fiber, the cooling member being disposed so as to be in contact with the support portion of the protection member.

[0010] Aspects of the present invention 5 From the above aspect 14 In any one of the fiber holding structures 1 to 4, the intermediate portion of the optical fiber contacts the inner surface of the fiber insertion hole of the shielding portion of the protective member.

[0011] Aspects of the present invention 6 From the above aspect 1 4 In any one of the fiber holding structures 1 to 4, an air layer is formed between the intermediate portion of the optical fiber and the inner surface of the fiber insertion hole of the shielding portion of the protective member.

[0012] According to another aspect of the present invention, there is provided a laser module capable of suppressing heat generation caused by laser light that is not coupled to an optical fiber. 7 The laser module comprises a laser element capable of emitting laser light and a laser diode according to any one of the first and second aspects. 6 and a lens that couples the laser light emitted from the laser element to the front end of the optical fiber of the fiber holding structure. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a partial cross-sectional view schematically showing a laser module according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a fiber holding structure in the laser module shown in FIG. [Figure 3] FIG. 3 is a diagram schematically showing dimensions of the main parts of the fiber holding structure shown in FIG. [Figure 4] FIG. 4 is a diagram schematically showing dimensions of the main parts of the fiber holding structure shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view schematically showing a modification of the fiber holding structure shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view schematically showing another modified example of the fiber holding structure shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view schematically showing another modified example of the fiber holding structure shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a laser module according to the present invention will be described in detail with reference to FIGS. 1 to 7. In FIGS. 1 to 7, identical or corresponding components are denoted by the same reference numerals, and redundant description will be omitted. In addition, in FIGS. 1 to 7, the scale and dimensions of each component may be exaggerated, and some components may be omitted. In the following description, unless otherwise specified, terms such as "first" and "second" are used only to distinguish components from each other, and do not represent a specific order or ranking.

[0015] FIG. 1 is a partial cross-sectional view schematically illustrating a laser module 1 according to a first embodiment of the present invention. As shown in FIG. 1, the laser module 1 according to this embodiment includes a bottom plate 10, a sidewall 11 fixed to an upper surface 10A of the bottom plate 10, a cover plate 12 mounted on the upper portion of the sidewall 11, a submount 13 disposed on the upper surface 10A of the bottom plate 10, a high-power semiconductor laser element 14 mounted on the submount 13, lenses 16 and 17 disposed on a lens mount 15 disposed on the upper surface 10A of the bottom plate 10, and a fiber holding structure 30 including an optical fiber 20 that transmits laser light P emitted from the semiconductor laser element 14 to the outside of the laser module 1. The laser element 14 may be, for example, a high-power laser diode with an output of several watts to 20 watts. Although not shown, a heat sink is connected to the bottom surface of the bottom plate 10. For convenience, in this embodiment, the −X direction in FIG. 1 will be referred to as the “front” or “forward” and the +X direction will be referred to as the “rear” or “rearward.”

[0016] 1, the fiber holding structure 30 is provided so as to penetrate one of the side walls 11. Furthermore, a lead 18 is provided so as to penetrate another side wall 11, and this lead 18 is connected to the laser element 14 by a bonding wire 19. With this configuration, power is supplied to the laser element 14 via the lead 18 and the bonding wire 19, and laser light P is emitted from the laser element 14 in the +X direction.

[0017] 2 is a cross-sectional view schematically illustrating the fiber holding structure 30. As shown in FIG. 2, the fiber holding structure 30 includes an optical fiber 20, a ferrule 40 that holds the optical fiber 20, a protective member 50 that covers the ferrule 40, and a flange 32 that is attached to the side wall 11 of the laser module 1. The optical fiber 20 has a front end 21 that is positioned so that laser light P emitted from the semiconductor laser element 14 and focused by the lens 17 is optically coupled to the front end 21. The optical fiber 20 includes a core, a cladding that covers the outer periphery of the core and has a lower refractive index than the core, and a coating that covers the outer periphery of the cladding and has a lower refractive index than the cladding. However, the coating is removed in the portion forward of the flange 32 to expose the cladding.

[0018] The ferrule 40 is a substantially cylindrical member made of, for example, zirconia, and has a fiber holding hole 41 formed at its center, penetrating in the X direction. This fiber holding hole 41 holds a first fixing portion 22 located behind the front end 21 of the optical fiber 20. The first fixing portion 22 of the optical fiber 20 is fixed inside the fiber holding hole 41 by an adhesive 60 filled in the fiber holding hole 41 of the ferrule 40, and some of this adhesive 60 overflows from the fiber holding hole 41 on the front surface 40A of the ferrule 40 and hardens around it, as shown in FIG.

[0019] The protective member 50 has a cylindrical support portion 51 that covers the outer periphery of the ferrule 40, and a disk-shaped shielding portion 52 that covers the front surface 40A of the ferrule 40. The support portion 51 and the shielding portion 52 may be formed as separate members, or the support portion 51 and the shielding portion 52 may be formed integrally. A fiber insertion hole 53 is formed in the center of the shielding portion 52, into which the intermediate portion 23 of the optical fiber 20, which is located between the front end 21 and the first fixing portion 22, is inserted. The support portion 51 of the protective member 50 may be fixed to the outer periphery of the ferrule 40 with an adhesive (not shown), or may be fixed to the outer periphery of the ferrule 40 by being fitted into the outer periphery of the ferrule 40.

[0020] A through hole 34 is formed in the center of the flange 32, penetrating in the X direction. A second fixing portion 24 of the optical fiber 20 is held in this through hole 34, which is located behind the first fixing portion 22 of the optical fiber 20. A support portion 51 of the protection member 50 may be fixed to this flange 32. By fixing the support portion 51 of the protection member 50 to the flange 32 in this manner, the first fixing portion 22 of the optical fiber 20 is fixed to the flange 32 via the ferrule 40 and the support portion 51 of the protection member 50, and further the second fixing portion 24 of the optical fiber 20 is held by the flange 32, so that the optical fiber 20 is held more stably. For example, the support portion 51 of the protection member 50 may be fixed to the flange 32 by press-fitting, or may be fixed to the flange 32 using an adhesive. If an adhesive is used to fix the flange 32 and the support portion 51 of the protective member 50, it is conceivable that the adhesive will leak out to the front surface 40A of the ferrule 40 due to capillary action through the gap between the support portion 51 of the protective member 50 and the outer circumferential surface of the ferrule 40. In this case, as will be described later, it is conceivable that light that propagates backward without being coupled to the core at the front end 21 of the optical fiber 20 will be incident on the adhesive, causing the adhesive to generate heat. However, if the flange 32 and the support portion 51 of the protective member 50 are fixed by press-fitting, such heat generation can be avoided. Note that the cladding at the second fixing portion 24 of the optical fiber 20 is covered with a coating, while the cladding at the first fixing portion 22, the intermediate portion 23, and the front end 21 is exposed.

[0021] The optical fiber 20 extends forward from the shielding portion 52 of the protective member 50, and the front end 21 of the optical fiber 20 is located forward of the shielding portion 52 of the protective member 50. The intermediate portion 23 of the optical fiber 20 inserted into the fiber insertion hole 53 of the shielding portion 52 of the protective member 50 may be in contact with the inner circumferential surface of the fiber insertion hole 53, or may be spaced apart from the inner circumferential surface of the fiber insertion hole 53. FIG. 2 shows an example in which the intermediate portion 23 of the optical fiber 20 is spaced apart from the inner circumferential surface of the fiber insertion hole 53.

[0022] As described above, in this embodiment, by covering the ferrule 40 with the protective member 50 and positioning the shielding portion 52 of the protective member 50 between the front surface 40A of the ferrule 40 and the front end 21 of the optical fiber 20, the laser light P that is not coupled to the front end 21 of the optical fiber 20 is blocked by the shielding portion 52 of the protective member 50 and becomes less likely to reach the adhesive 60 present around the fiber holding hole 41 on the front surface 40A of the ferrule 40, thereby reducing the amount of laser light P incident on the adhesive 60. Therefore, it is possible to prevent the adhesive 60 from generating heat due to absorption of the laser light P, which could result in burnout of the optical fiber 20.

[0023] Here, we consider the conditions under which the laser light P does not enter the adhesive 60 around the fiber holding hole 41 of the ferrule 40. The numerical aperture NA of the optical fiber 20 is given by the following equation (1) according to Snell's law at the front end 21 of the optical fiber 20, where θ is the maximum acceptance angle of the optical fiber 20 and n is the refractive index of the medium (air) present between the optical fiber 20 and the lens 17. NA=n sinθ (1)

[0024] Laser light P propagating at an angle exceeding the maximum acceptance angle θ of the optical fiber 20 propagates backward without coupling to the core at the front end 21 of the optical fiber 20. As shown in FIG. 3, the condition under which this laser light P does not enter the adhesive 60 solidified around the fiber holding hole 41 of the ferrule 40 is expressed by the following equation (2), where F is the diameter of the front end 21 of the optical fiber 20, G is the diameter of the adhesive 60 around the fiber holding hole 41 of the ferrule 40, and L is the distance from the front surface 40A of the ferrule 40 to the front end 21 of the optical fiber 20. G <F+2×Ltanθ ···(2)

[0025] Since the medium existing between the optical fiber 20 and the lens 17 is air, if n=1, the following equation (3) can be derived from the above equations (1) and (2). L>(GF) / (2×tan(asin(NA))) ···(3)

[0026] Therefore, by making the distance L from the front surface 40A of the ferrule 40 to the front end 21 of the optical fiber 20 greater than (GF) / 2×tan(asin(NA)), it is possible to prevent the laser light P from being incident on the adhesive 60. As an example, when the NA of the optical fiber 20 is 0.22, the diameter F of the front end 21 of the optical fiber 20 is 125 μm, and the diameter G of the adhesive 60 around the fiber holding hole 41 of the ferrule 40 is 500 μm, asin(0.22)=12.7°, and therefore, from equation (2), L>(500μm-125μm) / (2×tan(12.7°)) L>832μm Therefore, by making the distance L from the front surface 40A of the ferrule 40 to the front end 21 of the optical fiber 20 longer than 832 μm, it is possible to prevent the laser light P from entering the adhesive material 60.

[0027] The front end 21 of the optical fiber 20 is formed by a cut surface obtained by, for example, laser cleaving. For example, an anti-reflection coating that suppresses reflection of light in the wavelength band of the laser light P may be formed on the front end 21 of the optical fiber 20 so that the laser light P is efficiently coupled to the front end 21 of the optical fiber 20.

[0028] Here, if the inner diameter of the fiber insertion hole 53 of the shielding portion 52 becomes large, there is a risk that the laser light will enter the adhesive 60 and heat the adhesive 60, especially when aligning the laser light. For this reason, we will consider the condition for the inner diameter of the fiber insertion hole 53 that will prevent the laser light from entering the adhesive 60. As shown in Fig. 4, if the inner diameter of the fiber insertion hole 53 of the shielding portion 52 is D, the distance along the X direction from the front surface 52A of the shielding portion 52 to the front end 21 of the optical fiber 20 is A, and the half angle of the laser light Q with respect to the optical axis of the optical fiber 20 is φ, the condition under which a portion of the adhesive 60 will not be entered by the laser light Q is expressed by the following equation (4).

number

[0029] Therefore, when the inner diameter D of the fiber insertion hole 53 of the shielding portion 52 satisfies the following formula (6), the laser light Q is less likely to be incident on the adhesive material 60. F <D<2(L-A)tanφ+G ···(6)

[0030] As an example, when the diameter F of the front end 21 of the optical fiber 20 is 125 μm, the distance L from the front face 40A of the ferrule 40 to the front end 21 of the optical fiber 20 is 2 mm, the distance A along the X direction from the front face 52A of the shielding portion 52 to the front end 21 of the optical fiber 20 is 500 μm, the half angle φ of the laser light Q with respect to the optical axis of the optical fiber 20 is 12.7°, and the diameter G of the adhesive 60 around the fiber holding hole 41 of the ferrule 40 is 500 μm, then, from equation (6), 125 μm <D<1.63mm is derived. When D is within this range, for example, when D=0.5 mm, the laser light passing through the fiber insertion hole 53 of the shielding portion 52 is approximately 1 / 10 of the area where the laser light is incident when D=1.63 mm. In this way, when D is within the above range, the laser light is prevented from directly entering the adhesive 60. Therefore, the power density of the laser light impinging on the adhesive 60 is lower due to the presence of the shielding portion 52 compared to conventional fiber holding structures.

[0031] 2, the front end 21 of the optical fiber 20 is located forward of the shielding portion 52 of the protective member 50, but the front end 21 of the optical fiber 20 may be aligned (flush) with the front surface 52A of the shielding portion 52 of the protective member 50 in the X direction, or the front end 21 of the optical fiber 20 may be located inside the fiber insertion hole 53 behind the front surface 52A of the shielding portion 52 of the protective member 50. By making the front end 21 of the optical fiber 20 flush with the front surface 52A of the shielding portion 52 of the protective member 50 or positioning it further behind, it is possible to prevent accidental contact with the front end 21 of the optical fiber 20 when handling the laser module 1, and therefore the optical fiber 20 is less likely to be damaged.

[0032] 2, the intermediate portion 23 of the optical fiber 20 is spaced apart from the inner peripheral surface of the fiber insertion hole 53, but as described above, the intermediate portion 23 of the optical fiber 20 may be in contact with the inner peripheral surface of the fiber insertion hole 53. If the shielding portion 52 of the protective member 50 has a refractive index higher than that of the clad of the optical fiber 20, the intermediate portion 23 of the optical fiber 20 will come into contact with the inner peripheral surface of the fiber insertion hole 53, causing the laser light P that is not confined in the core of the optical fiber 20 and leaks into the clad to leak into the shielding portion 52 of the protective member 50, thereby reducing the amount of laser light P that reaches the adhesive 60 around the fiber holding hole 41 of the ferrule 40 described above.

[0033] In this regard, in the example shown in Figure 2, there is an air layer between the middle portion 23 of the optical fiber 20 and the inner surface of the fiber insertion hole 53 of the shielding portion 52 of the protective member 50, so the laser light P that is not confined in the core of the optical fiber 20 but leaks into the clad is confined within the clad and propagates downstream. However, by using an adhesive 60 that has a lower refractive index than the clad of the optical fiber 20 as the adhesive 60 that fixes the optical fiber 20, the laser light P that leaks into the clad is prevented from leaking into the adhesive 60 that has overflowed around the fiber holding hole 41 of the ferrule 40.

[0034] Furthermore, a high-reflection coating layer having a high reflectivity for light in the wavelength band of the laser light P may be formed on the front surface 52A of the shielding portion 52 of the protective member 50. Furthermore, in addition to the front surface 52A of the shielding portion 52 of the protective member 50, a high-reflection coating layer may also be formed on the front end surface 51A of the supporting portion 51. By forming such a high-reflection coating layer, part of the laser light P that is not coupled to the front end 21 of the optical fiber 20 can be reflected by the high-reflection coating layers of the shielding portion 52 and the supporting portion 51, thereby further reducing the possibility that the laser light P that is not coupled to the front end 21 of the optical fiber 20 will reach the adhesive 60 around the fiber holding hole 41.

[0035] When the support portion 51 and the shielding portion 52 of the protective member 50 are configured as separate members, the shielding portion 52 may be formed of, for example, quartz glass, sapphire, ceramic, or metal. The support portion 51 may be formed of a material that absorbs the laser light P more easily than the optical fiber 20 and has a high thermal conductivity, such as copper or aluminum. When the support portion 51 and the shielding portion 52 of the protective member 50 are integrally formed, the protective member 50 is preferably formed of a material that absorbs the laser light P more easily than the optical fiber 20 and has a high thermal conductivity, such as copper or aluminum. The protective member 50 (support portion 51) preferably has a higher thermal conductivity than the optical fiber 20, and preferably has a higher thermal conductivity than the ferrule 40. By forming the protective member 50 (support portion 51) from a material that has a higher thermal conductivity than the optical fiber 20 and the ferrule 40, heat generated in the optical fiber 20 and the ferrule 40 by the laser light P can be easily released to the outside via the protective member 50. Moreover, the protective member 50 may be formed integrally with the side wall 11 of the laser module 1 (FIG. 1).

[0036] 5, a cooling member 70 having a higher thermal conductivity than the optical fiber 20 may be disposed so as to be in contact with the support portion 51 of the protective member 50. The cooling member 70 may be formed of a metal such as copper or aluminum, and may have fins for heat dissipation. By disposing such a cooling member 70, heat generated in the optical fiber 20, the ferrule 40, and the protective member 50 can be easily dissipated to the outside via the cooling member 70. Furthermore, such a cooling member 70 may be formed integrally with the side wall 11 (FIG. 1) of the laser module 1.

[0037] In this case, an adhesive may be applied between the cooling member 70 and the flange 32 to fix the cooling member 70 and the flange 32 with the adhesive. In this case, as shown in FIG. 6, a recess 72 may be formed around the support portion 51 of the protection member 50 on the end face of the cooling member 70 on the flange 32 side. By forming such a recess 72, the adhesive 74 that fixes the cooling member 70 and the flange 32 can be separated from the optical fiber 20 and the ferrule 40, making it less likely that the adhesive 74 will leak into the space through which the laser light P propagates. This prevents the laser light P from entering the adhesive 74 and generating heat, improving the reliability of the laser module 1. Alternatively, the recess 72 may be formed by an inclined surface 76 as shown in FIG. 7.

[0038] The terms "front," "forward," "rear," "rearward," and other terms used herein to indicate positional relationships are used only to identify relative relationships between elements in connection with the illustrated embodiments, and are not intended to identify absolute positional relationships. Therefore, it should be noted that the directions implied by these terms will change accordingly if the position or orientation of the device changes.

[0039] As described above, according to the first aspect of the present invention, there is provided a fiber holding structure capable of suppressing heat generation due to light not coupled to an optical fiber. Specifically, the fiber holding structure according to the present invention can adopt the following configuration.

[0040] (Configuration 1) The fiber holding structure includes an optical fiber including a front end, a first fixing portion located rearward of the front end, and an intermediate portion located between the front end and the first fixing portion, a ferrule having a fiber holding hole for holding the first fixing portion of the optical fiber, an adhesive for fixing the first fixing portion of the optical fiber to the fiber holding hole of the ferrule, and a protective member for covering the ferrule. The protective member includes a support portion for covering the periphery of the ferrule, and a shielding portion for covering the front surface of the ferrule and having a fiber insertion hole into which the intermediate portion of the optical fiber is inserted.

[0041] In this way, by covering the ferrule with a protective member and positioning the shielding portion of the protective member between the front surface of the ferrule and the front end of the optical fiber, light that is not coupled to the front end of the optical fiber is blocked by the shielding portion of the protective member and is less likely to reach the adhesive present around the fiber holding hole on the front surface of the ferrule, thereby reducing the amount of light that enters the adhesive, thereby preventing the adhesive from absorbing light and generating heat, which could cause the optical fiber to burn.

[0042] (Configuration 2) In the above configuration 1, the fiber holding structure may further include a flange that holds a second fixing portion located behind the first fixing portion of the optical fiber. The support portion of the protection member may be fixed to the flange. With this configuration, the first fixing portion of the optical fiber is fixed to the flange via the ferrule and the support portion of the protection member, and the second fixing portion is held by the flange, so that the optical fiber is held more stably.

[0043] (Configuration 3) In the above configuration 1 or 2, a high-reflection coating layer having a high reflectance for light coupled to the front end of the optical fiber may be formed on the front surface of the shielding portion of the protective member. By forming such a high-reflection coating layer, a part of the light not coupled to the front end of the optical fiber can be reflected by the high-reflection coating layer of the shielding portion, thereby further reducing the possibility that the light not coupled to the front end of the optical fiber will reach the adhesive around the fiber holding hole.

[0044] (Configuration 4) In any of the above configurations 1 to 3, the protective member may be made of a material having a higher thermal conductivity than the optical fiber. By making the protective member from a material having a higher thermal conductivity than the optical fiber, heat generated in the optical fiber and the ferrule can be more easily released to the outside via the protective member.

[0045] (Configuration 5) In any of the above configurations 1 to 4, the fiber-holding structure may further include a cooling member having a higher thermal conductivity than the optical fiber. The cooling member is arranged so as to be in contact with the support portion of the protective member. Such a cooling member makes it easier to dissipate heat generated in the optical fiber, the ferrule, and the protective member to the outside via the cooling member.

[0046] (Configuration 6) In any one of the above configurations 1 to 5, the intermediate portion of the optical fiber may be in contact with an inner surface of the fiber insertion hole of the shielding portion of the protective member.

[0047] (Configuration 7) In any one of the above configurations 1 to 5, an air layer may be formed between the intermediate portion of the optical fiber and an inner surface of the fiber insertion hole of the shielding portion of the protective member.

[0048] (Configuration 8) According to a second aspect of the present invention, there is provided a laser module capable of suppressing heat generation due to laser light not coupled to an optical fiber, the laser module comprising: a laser element capable of emitting laser light; a fiber holding structure according to any one of the above aspects 1 to 7; and a lens that couples the laser light emitted from the laser element to the front end of the optical fiber in the fiber holding structure.

[0049] Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and may be embodied in various different forms within the scope of the technical concept thereof.

[0050] This application is based on and claims priority from Japanese Patent Application No. 2022-176000, filed on November 2, 2022, the disclosure of which is incorporated herein by reference in its entirety. [Industrial Applicability]

[0051] The present invention is suitably used for a fiber holding structure that holds an optical fiber to which laser light emitted from a laser element is coupled. [Explanation of symbols]

[0052] 1 laser module 10 Bottom plate 11 Side wall 12 Cover plate 13 Submount 14 Laser element 16,17 Lens 20 Optical Fiber 21 Front end 22 First fixing part 23 Middle section 24 Second fixing part 30 Fiber holding structure 32 flange 34 Through hole 40 ferrules 40A front 41 Fiber holding hole 50 Protective material 51 Support part 52 Shielding part 53 Fiber insertion hole 60 Adhesive 70 Cooling material 72 recess

Claims

1. an optical fiber including a front end, a first fixing portion located rearward of the front end, and an intermediate portion located between the front end and the first fixing portion; a ferrule having a fiber holding hole formed therein for holding the first fixing portion of the optical fiber; an adhesive that fixes the first fixing portion of the optical fiber to the fiber holding hole of the ferrule; a flange attached to a side wall of a laser module, the flange holding a second fixing portion of the optical fiber positioned behind the first fixing portion; A protective member covering the ferrule, a support portion that covers the periphery of the ferrule and is fixed to the flange; a shielding portion that covers the front surface of the ferrule and has a fiber insertion hole into which the intermediate portion of the optical fiber is inserted; A protective member including A fiber holding structure comprising:

2. The fiber holding structure according to claim 1 , wherein a highly reflective coating layer having a high reflectivity for light coupled to the front end of the optical fiber is formed on a front surface of the shielding portion of the protective member.

3. The fiber holding structure according to claim 1 , wherein the protective member is made of a material having a higher thermal conductivity than the optical fiber.

4. The fiber holding structure according to claim 1 , further comprising a cooling member having a thermal conductivity higher than that of the optical fiber, the cooling member being arranged so as to be in contact with the support portion of the protection member.

5. The fiber holding structure according to claim 1 , wherein the intermediate portion of the optical fiber contacts an inner surface of the fiber insertion hole of the shielding portion of the protective member.

6. 2. The fiber holding structure according to claim 1, wherein an air layer is formed between the intermediate portion of the optical fiber and the inner surface of the fiber insertion hole of the shielding portion of the protective member.

7. a laser element capable of emitting laser light; A fiber holding structure according to any one of claims 1 to 6; a lens that couples the laser light emitted from the laser element to the front end of the optical fiber of the fiber holding structure; A laser module comprising:

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