JP2020160343A - End part structure and semiconductor laser module - Google Patents

Abstract

To provide an end part structure, being an end part structure in an optical fiber, and a semiconductor laser module that have light propagation in a cladding mode suppressed.SOLUTION: There is provided an end part structure in an optical fiber that comprises: an optical fiber 11 including a core part 11a and a cladding part 11b formed on an outer periphery of the core part; and an optical member 12 that includes a first end face 12a, a second end face 12b having a smaller area than an area of the first end face, and a tapered part 12c having a tapered shape a sectional area of which is reduced as going from the first end face to the second end face. The second end face of the optical member is connected to an end face of the core part of the optical fiber, and the optical member is configured such that light input from a first end face side is totally reflected by an inner side face of the tapered part to reduce a beam diameter of the light and is then output from the second end face.SELECTED DRAWING: Figure 2

Description

The present invention relates to end structures and semiconductor laser modules in optical fibers.

Semiconductor laser modules are also used in industrial fields such as processing and welding. In the semiconductor laser module, a glass capillary for fixing the optical fiber is provided on the outer periphery of the optical fiber as a configuration of a part for coupling the laser light output from the semiconductor laser element to the optical fiber, and the glass capillary is fixed on the outer periphery of the glass capillary. A configuration for providing a light absorber is disclosed. The optical fiber and the glass capillary are fixed by a first fixing material such as resin. The glass capillary and the light absorber are fixed by a second fixing material such as resin (Patent Document 1). In this configuration, a part of the laser beam input to the optical fiber propagates in the clad mode without being coupled to the core portion. Such laser light gradually leaks from the clad portion during propagation, passes through the two fixing materials and the glass capillary, reaches the light absorber, and is absorbed by the light absorber. In the portion where the laser beam is coupled to the optical fiber, the coating of the optical fiber is removed and the clad portion is exposed. According to the configuration of Patent Document 1, it is possible to suppress damage to the coating.

International Publication No. 2015/037725

In the industrial field, high power of the laser beam of the light source is required. In the configuration of Patent Document 1, as the power of the laser beam increases, the power of the laser beam propagating in the clad mode among the laser beams increases. As a result, the laser beam propagating in the clad mode and leaking from the clad portion may damage the first or second fixing material. In particular, since the first fixing material is adjacent to the outer periphery of the clad portion, the power density of the leaked laser beam is high, and the first fixing material is more easily damaged than the second fixing material. Further, the laser beam leaked from the clad portion may damage the resin coating of the optical fiber.

The present invention has been made in view of the above, and an object of the present invention is to provide an end structure in an optical fiber, an end structure in which light propagation in a clad mode is suppressed, and a semiconductor laser module. ..

In order to solve the above-mentioned problems and achieve the object, the end structure according to one aspect of the present invention is an end structure in an optical fiber, and is a clad formed on a core portion and an outer periphery of the core portion. It has an optical fiber having a portion, a first end face, a second end face having an area smaller than the area of the first end face, and a tapered shape in which the cross-sectional area is reduced from the first end face to the second end face. An optical member having a tapered portion is provided, the second end surface of the optical member is connected to the end surface of the core portion of the optical fiber, and the optical member is the light input from the first end surface side. Is completely reflected on the inner surface of the tapered portion to reduce the beam diameter of the light, and is output from the second end surface.

The end structure according to one aspect of the present invention is characterized in that the refractive index of the optical member is substantially the same as the refractive index of the core portion of the optical fiber.

The end structure according to one aspect of the present invention is characterized in that the sine value of the incident angle of the light from the second end surface of the optical member to the core portion of the optical fiber is equal to or less than the numerical aperture of the optical fiber. And.

In the end structure according to one aspect of the present invention, the optical member outputs the beam diameter of the light input from the first end surface side to be equal to or less than the core diameter of the core portion from the second end surface. It is characterized by that.

The end structure according to one aspect of the present invention is characterized in that the area of the second end face of the optical member is equal to or less than the area of the end face of the core portion of the optical fiber.

The end structure according to one aspect of the present invention is characterized in that the second end surface of the optical member is connected only to the end surface of the core portion of the optical fiber.

The end structure according to one aspect of the present invention is characterized in that the optical member is located between the tapered portion and the second end surface and includes a connecting portion having a predetermined length.

The end structure according to one aspect of the present invention is characterized by including an end cap connected to the first end surface of the optical member and having an input end surface having a larger area than the first end surface.

A semiconductor laser module according to an aspect of the present invention is characterized by comprising the end structure, a semiconductor laser element, and an optical system that guides a laser beam output from the semiconductor laser element to the end structure. To do.

According to the present invention, there is an effect that light propagation in the clad mode is suppressed.

FIG. 1 is a schematic plan view of a semiconductor laser module having an end structure according to the first embodiment. FIG. 2 is a schematic cross-sectional view of the end structure shown in FIG. FIG. 3 is a diagram illustrating an input state of laser light with respect to the end structure shown in FIG. FIG. 4 is a schematic cross-sectional view of the end structure according to the second embodiment. FIG. 5 is a schematic cross-sectional view of the end structure according to the third embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described below. Further, in the description of the drawings, the same or corresponding elements are appropriately designated by the same reference numerals, and duplicate description will be omitted as appropriate. In addition, it should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, etc. may differ from the reality.

(Embodiment 1)
FIG. 1 is a schematic plan view of a semiconductor laser module having an end structure according to the first embodiment. The semiconductor laser module 100 includes a package 101 which is a housing, an LD height adjusting plate 102 which is sequentially loaded inside the package 101, a submount 103-1-103-6, and six semiconductor laser elements 104-1. It is provided with 104-6. Package 101 includes a lid, but is not shown in FIG. 1 for the sake of explanation. The semiconductor laser module 100 includes a lead pin 105 that injects a current into the semiconductor laser element 104-1-104-6. The semiconductor laser module 100 includes first lenses 106-1 to 106-6 and second lenses 106-1 to 106-6, which are optical elements sequentially arranged on the optical path of the laser light output by the semiconductor laser elements 104-1 to 104-6. It includes lenses 107-1 to 107-6, mirrors 108-1 to 108-6, a third lens 109, an optical filter 110, and a fourth lens 111. The first lens 106-1 to 106-6, the second lens 107-1 to 107-6, the mirror 108-1 to 108-6, the third lens 109, the optical filter 110, and the fourth lens 111 are each in the package 101. It is fixed inside. Further, the semiconductor laser module 100 includes an end structure 10 arranged so as to face the fourth lens 111, and an optical fiber 112 connected to the end structure 10 by fusion splicing or the like. One end of the optical fiber 112 on the side opposite to the side connected to the end structure 10 extends to the outside of the package 101.

The semiconductor laser elements 104-1 to 104-6 are arranged at different heights from the bottom surface of the package 101 by the LD height adjusting plate 102. Further, the first lens 106-1 to 106-6, the second lens 107-1 to 107-6, and the mirror 108-1 to 108-6 are arranged at the same height as one corresponding semiconductor laser element. There is. A loose tube 114 is provided at the insertion portion of the optical fiber 112 into the package 101, and the boot 113 is externally fitted to a part of the package 101 so as to cover a part of the loose tube 114.

Each semiconductor laser element 104-1-104-6 is supplied with electric power from the lead pin 105 to output laser light. Each of the output laser beams is made substantially parallel light by the first lens 106-1 to 106-6 and the second lens 107-1 to 107-6, respectively. Next, each laser beam is reflected in the direction of the optical fiber 112 by one mirror 108-1 to 108-6 arranged at the corresponding height. Then, each laser beam is focused by the third lens 109 and the fourth lens 111. That is, the first lens 106-1 to 106-6, the second lens 107-1 to 107-6, the mirror 108-1 to 108-6, the third lens 109, and the fourth lens 111 end each laser beam. It constitutes an optical system that leads to the structure 10.

The end structure 10 couples each laser beam focused by the fourth lens 111 to the optical fiber 112. The optical fiber 112 outputs each coupled laser beam to the outside of the semiconductor laser module 100.

Next, each component of the semiconductor laser module 100 will be described in more detail. The package 101, which is a housing, is preferably made of a material having good thermal conductivity in order to suppress an internal temperature rise, and may be a metal member made of various metals.

As described above, the LD height adjusting plate 102 is fixed in the package 101, adjusts the height of the semiconductor laser elements 104-1 to 104-6, and outputs the semiconductor laser elements 104-1 to 6 The optical paths of the laser light do not interfere with each other. The LD height adjusting plate 102 may be integrally configured with the package 101.

The submounts 103-1-103-6 are fixed on the LD height adjusting plate 102, and assist the heat dissipation of the mounted semiconductor laser element 104-1-104-6. Therefore, the submounts 103-1-103-6 are preferably made of a material having good thermal conductivity, and may be a metal member made of various metals.

The semiconductor laser element 104-1-104-6 is a high-output semiconductor laser element having an output laser light intensity of 1 W or more and further 10 W or more. In the present embodiment, the light intensity of the laser light output by the semiconductor laser element 104-1-104-6 is, for example, 11 W. Further, the semiconductor laser element 104-1-104-6 outputs laser light having a wavelength of, for example, 900 nm to 1000 nm. However, the wavelength and intensity of the laser beam are not particularly limited. Although the semiconductor laser module 100 includes six semiconductor laser elements 104-1 to 104-6, a plurality of semiconductor laser elements other than six may be used, or one may be used.

The lead pin 105 supplies electric power to the semiconductor laser elements 104-1 to 10-6 via a bonding wire (not shown). The power to be supplied may be a constant voltage, but may be a modulated voltage.

The first lens 106-1 to 106-6 is, for example, a cylindrical lens having a focal length of 0.3 mm. The first lenses 106-1 to 106-6 are arranged at positions where the output light of one corresponding semiconductor laser element is substantially parallel light in the vertical direction.

The second lenses 107-1 to 107-6 are, for example, cylindrical lenses having a focal length of 5 mm. The second lenses 107-1 to 107-6 are arranged at positions where the output light of the semiconductor laser element is substantially parallel light in the horizontal direction.

The mirrors 108-1 to 108-6 may be mirrors provided with various metal films or dielectric films, and have high reflectance at the wavelength of the laser beam output by the semiconductor laser element 104-1-104-6. Is more preferable. Further, the mirrors 108-1 to 108-6 can finely adjust the reflection direction so that the laser beam of one corresponding semiconductor laser element is suitably coupled to the optical fiber 112.

The third lens 109 and the fourth lens 111 are, for example, cylindrical lenses having focal lengths of 12 mm and 5 mm and having orthogonal curvatures to each other, and condense the laser light output by the semiconductor laser elements 104-1 to 104-16. , Suitable for coupling to the optical fiber 112. The positions of the third lens 109 and the fourth lens 111 with respect to the optical fiber 112 are such that, for example, the coupling efficiency of the laser light output by the semiconductor laser element 104-1-104-6 to the optical fiber 112 is 85% or more. Has been adjusted.

The optical filter 110 is, for example, a low-pass filter that reflects light having a wavelength of 1060 nm to 1080 nm and transmits light having a wavelength of 900 nm to 1000 nm. As a result, the optical filter 110 transmits the laser light output by the semiconductor laser element 104-1-104-6, and the semiconductor laser element 104-1-104-6 is irradiated with light having a wavelength of 1060 nm to 1080 nm from the outside. To prevent that. Further, the optical filter 110 has an optical axis of the laser beam so that the output laser beam of the semiconductor laser element 104-1-104-6 slightly reflected by the optical filter 110 does not return to the semiconductor laser element 104-1 to 6 It is arranged at an angle to the laser. The passing wavelength of the optical filter 110 is set to 1060 nm to 1080 nm, but the wavelength is not limited to this wavelength. However, the optical filter 110 is not always necessary.

The optical fiber 112 is an optical fiber made of a quartz glass-based material. The optical fiber 112 may be, for example, a multimode optical fiber having a core diameter of 105 μm and a clad diameter of 125 μm in the clad portion, but may be a single mode optical fiber. The NA of the optical fiber 112 is, for example, 0.15 to 0.22.

The boot 113 is inserted with the optical fiber 112 to prevent damage due to bending of the optical fiber 112. The boot 113 may be a metal boot, but the material is not particularly limited, and rubber, various resins, plastic, or the like may be used. However, boots 113 are not always necessary.

The loose tube 114 is inserted with the optical fiber 112 to prevent damage due to bending of the optical fiber 112. Further, the loose tube 114 is fixed to the optical fiber 112, and as a result, the position of the optical fiber 112 is prevented from being displaced when a pulling force is applied to the optical fiber 112 in the longitudinal direction. May be good. However, the loose tube 114 is not always necessary.

(Structure of end structure)
Next, the configuration of the end structure 10 will be specifically described. FIG. 2 is a schematic cross-sectional view of the end structure 10. The condensing unit 115 is composed of a third lens 109 and a fourth lens 111, and condenses the laser beam L1 output by the semiconductor laser element 104-1 to 104-16, and has an end structure. It is to be input to 10.

The end structure 10 includes an optical fiber 11 and an optical member 12.

The optical fiber 11 is an optical fiber made of a quartz glass-based material, and is a coating 11c made of a core portion 11a, a clad portion 11b formed on the outer periphery of the core portion 11a, and a resin formed on the outer periphery of the clad portion 11b. And have. Further, the optical fiber 11 has an end surface 11aa of the core portion 11a. The end face of the clad portion 11b exists on the outer periphery of the end face 11aa. The coating 11c has been removed in the vicinity of the end face 11aa, and the clad portion 11b is exposed. The optical fiber 11 may be, for example, a multimode optical fiber having a core diameter of 105 μm in the core portion 11a and a clad diameter of 125 μm in the clad portion 11b, but is not particularly limited and may be a single mode optical fiber. The numerical aperture (NA) of the optical fiber 11 is, for example, 0.15 to 0.22.

The optical member 12 is made of, for example, a quartz glass material. In the present embodiment, the refractive index of the optical member 12 is the same as the refractive index of the core portion 11a of the optical fiber 11. The optical member 12 has an end surface 12a as a first end surface, an end surface 12b as a second end surface, and a tapered portion 12c. The end face 12a is circular in this embodiment, but may have other shapes such as an ellipse. The end face 12b has an area smaller than the area of the end face 12a. The end face 12b is circular in this embodiment, but may have other shapes such as an ellipse. Further, the end face 12a and the second end face may have different shapes. In the present embodiment, the end face 12a and the end face 12b are parallel, but may be non-parallel. The tapered portion 12c has a tapered shape in which the cross-sectional area is reduced from the end face 12a to the end face 12b. Here, the cross-sectional area of the tapered portion 12c is the cross-sectional area of the optical member 12 in the cross section perpendicular to the optical axis. The optical axis of the optical member 12 passes through, for example, the center of the end face 12a and the center of the end face 12b, and is perpendicular to the end face 12a and the end face 12b. In this embodiment, the optical member 12 has the shape of a truncated cone.

The end surface 12b of the optical member 12 is connected to the end surface 11aa of the core portion 11a of the optical fiber 11 by, for example, welding. If the optical member 12 is made of the same quartz-based glass material as the core portion 11a, it is preferable because the refractive index is the same as that of the core portion 11a and the connection loss can be reduced. In the present embodiment, it is assumed that the end face 12b is connected only to the end face 11aa of the core portion 11a and not to the end face of the clad portion 11b. Further, in the present embodiment, it is assumed that the diameter of the end face 12b is equal to or less than the core diameter of the core portion 11a, and the area of the end face 12b is equal to or less than the area of the end face 11aa of the core portion 11a.

It is assumed that the beam diameter of the laser beam L1 is equal to or smaller than the diameter of the end face 12a when the condensing unit 115 condenses the laser beam L1 and inputs it to the end structure 10. The beam diameter of the laser beam includes a peak and may be defined as the diameter of the region of 1 / e ² or more of the intensity of the peak intensity. When a beam of laser light output by a plurality of semiconductor laser elements is included like the beam of the laser light L1 of the present embodiment, the beam is not circular, so that it includes a peak and has an intensity of 1 / e ² or more of the peak intensity. The diameter of the smallest circle that covers the region of is defined as the beam diameter.

The optical member 12 totally reflects the laser beam L1 input from the end face 12a side on the inner surface of the tapered portion 12c to reduce the beam diameter of the laser beam L1 and outputs the laser beam L1 from the end face 12b. The reduced laser beam L2 output from the end face 12b propagates through the core portion 11a connected to the end face 12b. As a result, it is possible to significantly suppress or prevent a part of the laser beam L1 from being coupled to the clad portion 11b and propagating in the clad mode.

That is, in the end structure 10, the beam diameter of the laser beam L1 is reduced by utilizing the total reflection of the light. As a result, the beam diameter of the laser beam L1 can be effectively reduced to propagate the core portion 11a, so that a part of the laser beam L1 propagates in the clad mode is significantly suppressed or prevented. As a result, it is possible to prevent the laser beam propagating in the clad mode from reaching the coating 11c made of resin, for example, and damaging the coating 11c.

The input state of the laser beam with respect to the end structure 10 will be described more specifically with reference to FIG. In FIG. 3, the diameter of the end face 12a of the optical member 12 is D1, and the diameter of the end face 12b is D2. Further, the light ray R of the laser beam L1 is incident on the end surface 12a on the end surface 12a having a diameter D1 in the optical member 12 at an incident angle (°) of θ1. Here, the light ray R indicates a light component of the laser beam L1 having the maximum angle of incidence on the end face 12a. The refraction angle (°) at this time is θ2. Let N be the refractive index of the optical member 12 at the wavelength of the laser beam L1. The tapered portion 12c of the optical member 12 is surrounded by air, and the refractive index of the air is 1. Let θ3 be the angle (taper angle) (°) of the tapered portion 12c with respect to the optical axis. Assuming that the incident angle (°) of the light ray R with respect to the inner surface of the tapered portion 12c is θ4, when the light ray R is totally reflected at the inner surface of the tapered portion 12c, that is, at the interface with air, the following equation (1) is applied according to Snell's law. ) Holds.
N × sin θ4 = 1 × sin (90 °) ・ ・ ・ (1)

Further, for θ1, θ2, θ3, and θ4, the following equations (2) and (3) hold.
1 × sinθ1 = N × sinθ2 ・ ・ ・ (2)
θ4 = 90 (°) −θ3 + θ2 ・ ・ ・ (3)

Further, since the light ray R is incident on the inner surface of the tapered portion 12c, the following equation (4) holds.
θ3> θ2 ・ ・ ・ (4)

Further, assuming that the incident angle of the light ray R from the end surface 12b of the optical member 12 to the core portion 11a of the optical fiber 11 is θ5, when the refractive index of the laser beam L1 of the core portion 11a at the wavelength is N, the core portion 11a is used. The refraction angle is also θ5. At this time, when the light ray R propagates while being totally reflected in the core portion 11a, the following equation (5) holds.
sin θ5 ≦ (NA of optical fiber 11) ・ ・ ・ (5)
Further, θ4 is represented by the following equation (5).
θ5 = 2 × θ3-θ2 ・ ・ ・ (6)
In the formulas (5) and (6), the incident angle of the light ray R from the optical member 12 to the core portion 11a is equal to or less than the angle satisfying the total reflection condition in the core portion 11a of the optical fiber 11, that is, the sine value of the incident angle is light. If it is NA or less of the fiber 11, it is shown that the light ray R does not leak to the clad portion 11b and propagates in the propagation mode of the core portion 11a.

From the above, it is preferable that the equations (1) and (4) are satisfied in order to suppress the light propagation in the clad mode, and it is more preferable that the equation (5) is satisfied. Further, the equal sign does not have to hold in the equation (5). However, if light propagation in the clad mode is allowed to some extent, sin θ5 in the equation (5) may be larger than NA of the optical fiber 11 to some extent.

The angle of incidence of the light beam R from the optical member 12 to the core portion 11a and the refraction angle are equal because the refractive indexes of the optical member 12 and the core portion 11a are the same. The refractive indexes of the optical member 12 and the core portion 11a may be different, but may be substantially the same. Here, substantially equal includes a case where the reflection due to the difference in refractive index at the interface between the optical member 12 and the core portion 11a has a certain degree of difference in refractive index within an allowable range and a case where there is no difference in refractive index. When the refractive index of the optical member 12 and the core portion 11a are different, the equations (5) and (6) may be modified and applied as is well known according to the difference in the refractive index.

Further, assuming that the length of the tapered portion 12c in the optical axis direction is L, L can be set as follows, for example. First, the diameter of the end face 12b is represented by the following equation (7).
D2 = D1-2 × L × tan θ3 ・ ・ ・ (7)
Therefore, if the following equation (8) is established, the diameter D2 of the end face 12b can be set to the core diameter D3 or less of the core portion 11a, and the beam diameter of the laser beam L1 can be set to the core diameter D3 or less from the end face 12b. It can be easily output. It is not necessary that the equal sign holds in the equation (8).
D1-2 × L × tan θ3 ≦ D3 ・ ・ ・ (8)

The optical member 12 is configured so that even if the diameter D2 of the end face 12b is larger than the core diameter D3 of the core portion 11a, the beam diameter of the laser beam L1 can be set to the core diameter D3 or less and output from the end face 12b. You may.

As described above, according to the end structure 10 according to the first embodiment, light propagation in the clad mode is suppressed.

(Embodiment 2)
FIG. 4 is a schematic cross-sectional view of the end structure according to the second embodiment. The end structure 10A has a structure in which the optical member 12 is replaced with the optical member 14 in the structure of the end structure 10 according to the first embodiment. This end structure 10A can be used in place of the end structure 10 in, for example, the semiconductor laser module 100.

The optical member 14 is made of, for example, a quartz glass material. The refractive index of the optical member 14 is the same as the refractive index of the core portion 11a of the optical fiber 11. The optical member 14 has an optical member 12 and a connecting portion 13.

The optical member 12 is the same as the optical member 12 of the end structure 10, and has an end surface 12a as a first end surface, an end surface 12b, and a tapered portion 12c.

The connecting portion 13 is a cylindrical member having a predetermined length, having an end surface 13a and an end surface 13b as a second end surface, and having a constant cross-sectional area and cross-sectional shape in the longitudinal direction. Then it is cylindrical. The end surface 12b of the optical member 12 and the end surface 13a of the connecting portion 13 have substantially the same shape. The optical member 12 and the connecting portion 13 are formed by integrally forming, for example, a glass rod by chemical polishing such as mechanical polishing or etching. The connecting portion 13 is located between the tapered portion 12c and the end surface 13b which is the second end surface, and has a cross section having the same shape as the end surface 13b. The diameter and area of the end face 13b are preferably less than or equal to the diameter and area of the end face 11aa of the core portion 11a.

The end surface 13b of the connecting portion 13 as the second end surface of the optical member 14 is connected to the end surface 11aa of the core portion 11a of the optical fiber 11 by, for example, welding.

Since the optical member 14 is connected to the optical fiber 11 at the connecting portion 13, the tapered portion 12c is extremely suppressed or prevented from being thermally deformed even when the optical member 14 is connected by welding. As a result, the effect of reducing the beam diameter of the laser beam L1 due to total reflection on the inner surface of the tapered portion 12c is more exhibited as designed. Further, since the connecting portion 13 has a tubular shape, the welding work with the optical fiber 11 can be performed more easily. The length of the connecting portion 13 is preferably such that the heat due to welding does not adversely affect the tapered portion 12c.

(Embodiment 3)
FIG. 5 is a schematic cross-sectional view of the end structure according to the third embodiment. This end structure 10B can be used in place of the end structure 10 in, for example, the semiconductor laser module 100.

The end structure 10B has a structure in which an end cap 15 is added to the structure of the end structure 10. The end cap 15 includes a cylindrical input portion 15a and a truncated cone-shaped output portion 15b. The end face of the input unit 15a is the input end face 15aa, and the end face of the output unit 15b is the output end face 15ba. The end cap 15 is connected to the end surface 12a of the optical member 12 by welding or the like on the output end surface 15ba. Since the output unit 15b has a truncated cone shape in which the diameter decreases toward the output end surface 15ba side, the difference in diameter between the output end surface 15ba and the end surface 12a of the optical member 12 is relatively small. Therefore, the alignment and connection between the optical member 12 and the end cap 15 become easy.

The input end surface 15aa of the end cap 15 has a larger area than the end surface 12a of the optical member 12 which is the first end surface. As a result, when the laser beam L1 is focused and input to the end structure 10B, the laser beam L1 is input to the input end surface 15aa of the end cap 15 rather than directly input to the end surface 12a of the optical member 12. Input with the power density of the beam of. As a result, the occurrence of damage to the input end face 15aa due to the power of the laser beam L1 is suppressed. Here, the material of the end cap 15 is preferably a material having a refractive index similar to that of the optical member 12, and is preferably a quartz-based glass material having the same refractive index as that of the optical member 12, for example. The end cap 15 has a shape that is a combination of a cylindrical shape and a truncated cone shape, but the shape of the end cap is not limited to this.

In the above embodiment, the optical fiber 11 constituting the end structure is connected to the optical fiber 112, but the optical fiber 112 may form the end structure according to the embodiment instead of the optical fiber 11. Good. Alternatively, the optical fiber 11 may extend to the outside of the semiconductor laser module.

Further, in the above embodiment, the second end face of the optical member is connected only to the end face of the core portion of the optical fiber, but as long as the light propagation in the clad mode is suppressed, the end face of the clad portion is also connected. It may be connected. Further, the area of the second end face of the optical member may be larger than the area of the end face of the core portion of the optical fiber as long as the light propagation in the clad mode is suppressed.

Further, an antireflection film may be formed on the first end surface of the optical member or the input end surface of the end cap.

Further, in the above embodiment, the end structure is used for coupling a laser beam output from a light source such as a semiconductor laser element to an optical fiber. However, the use of the end structure is not limited to this. For example, the end structure may be provided on the output side of a processing laser device using a fiber laser or the like, for example, on the output side of a delivery optical fiber such as a head portion. In the processing laser device, the laser beam irradiated to the processing target may be reflected and returned. When such return light propagates in the optical fiber constituting the processing laser device in the clad mode, a part of the return light may leak from the clad portion and damage the device. Therefore, by providing the end structure on the output side of the processing laser apparatus, it is possible to suppress or prevent the propagation of the return light in the clad mode.

Moreover, the present invention is not limited by the above-described embodiment. The present invention also includes a configuration in which the above-mentioned components are appropriately combined. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

10, 10A, 10B End structure 11, 112 Optical fiber 11a Core part 11aa, 12a, 12b, 13a, 13b End face 11b Clad part 11c Coating 12, 14 Optical member 12c Tapered part 13 Connection part 15 End cap 15aa Input end face 15a Input Part 15b Output part 15ba Output end face 100 Semiconductor laser module 101 Package 102 LD Height adjustment plate 103-1-103-6 Submount 104-1-104-6 Semiconductor laser element 105 Lead pin 106-1 to 106-6 First lens 107-1 to 107-6 2nd lens 108-1 to 108-6 Mirror 109 3rd lens 110 Optical filter 111 4th lens 113 Boots 114 Loose tube 115 Condensing part L1 Laser light L2 Laser light R light

Claims (9)

It is an end structure in an optical fiber and
An optical fiber having a core portion and a clad portion formed on the outer periphery of the core portion,
An optical member having a first end face, a second end face having an area smaller than the area of the first end face, and a tapered portion having a tapered shape in which the cross-sectional area is reduced from the first end face to the second end face. ,
The second end surface of the optical member is connected to the end surface of the core portion of the optical fiber, and the optical member receives all the light input from the first end surface side on the inner surface of the tapered portion. An end structure characterized in that it is configured to reflect and reduce the beam diameter of the light and output it from the second end surface. The end structure according to claim 1, wherein the refractive index of the optical member is substantially the same as the refractive index of the core portion of the optical fiber. The end portion according to claim 1 or 2, wherein the sine value of the incident angle of the light from the second end surface of the optical member to the core portion of the optical fiber is equal to or less than the numerical aperture of the optical fiber. Construction. The end according to claim 1, wherein the optical member sets the beam diameter of the light input from the first end surface side to be equal to or less than the core diameter of the core portion and outputs the light from the second end surface. Part structure. The end structure according to any one of claims 1 to 4, wherein the area of the second end surface of the optical member is equal to or less than the area of the end surface of the core portion of the optical fiber. The end structure according to any one of claims 1 to 4, wherein the second end surface of the optical member is connected only to the end surface of the core portion of the optical fiber. The end portion according to any one of claims 1 to 6, wherein the optical member is located between the tapered portion and the second end surface and includes a connecting portion having a predetermined length. Construction. The end portion according to any one of claims 1 to 7, further comprising an end cap having an input end surface having a larger area than the first end surface, which is connected to the first end surface of the optical member. Construction. The end structure according to any one of claims 1 to 8.
Semiconductor laser element and
An optical system that guides the laser beam output from the semiconductor laser device to the first end surface of the end structure,
A semiconductor laser module characterized by being equipped with.

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