JP7164460B2 - Optical combiner, laser device, and method for manufacturing optical combiner - Google Patents

Description

The present invention relates to an optical combiner, a laser device, and a method for manufacturing an optical combiner that can suppress the influence of return light.

Since laser devices are capable of non-contact processing, they are used in various fields such as the processing field and the medical field, and there is a demand for higher output power.

As one of the methods for realizing such a high-output laser device, there is a method of collectively outputting laser beams output from a plurality of optical fibers and outputting them from a single optical fiber. Patent Literature 1 listed below describes an optical fiber component that is an optical combiner that can be used in such a laser device.

In this optical combiner, a plurality of input optical fibers are connected to one end of a tapered optical fiber. This tapered optical fiber has a diameter-reduced portion in which the outer diameter is reduced from one side to the other side, and one output optical fiber is connected to the end portion on the other side where the outer diameter is small. . Further, a portion of the plurality of input optical fibers, a tapered optical fiber, and a portion of the single output optical fiber are arranged in a case, and the respective input optical fibers and the case are fixed with resin, The optical fiber for output and the case are fixed with another resin.

Japanese Patent No. 5648131

The optical combiner described in Patent Document 1 is used for high-power lasers and the like. In a laser device using this optical combiner, when light is incident from each of the input optical fibers, the light is emitted from the output optical fiber via the tapered optical fiber, and the emitted light hits the workpiece or the like. It may be reflected and re-injected into the output fiber. The light that has entered the output fiber propagates from the output fiber toward the input fiber as return light, and this return light may leak inside the case. When light leaks within the case, the light may be reflected by the inner wall of the case and may re-inject into one of the plurality of input optical fibers, and the light may propagate through the input optical fibers as return light. obtain. Further, the re-incident light may be absorbed by the coating layer of the optical fiber or the fixing resin for fixing the optical fiber, and the coating layer or the fixing resin that absorbs the light may generate heat. In Patent Literature 1, a scattering material that scatters the leaked light is provided. However, there is a demand for suppressing the influence of return light entering the input optical fiber from the output optical fiber side by other methods.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an optical combiner, a laser device, and a method for manufacturing an optical combiner that can suppress the influence of returned light.

In order to solve the above-mentioned problems, an optical combiner of the present invention connects a plurality of input optical fibers including a first input optical fiber and a second input optical fiber to one end of each of the plurality of input optical fibers. and a tubular case surrounding the sides of the plurality of input optical fibers, wherein the first input optical fiber and the second input optical fiber are individually provided with the same incident angle. When light is incident, the NA of the light incident from the first input optical fiber and emitted from the output optical fiber is the NA of the light incident from the second input optical fiber and emitted from the output optical fiber. A part of the light propagating from the output optical fiber toward the input optical fiber leaks and is reflected on the inner wall of the case to be reflected by the first input optical fiber. The optical fiber is arranged at a position where energy of light re-entering the optical fiber is smaller than energy of light re-entering the second input optical fiber after the leaked light is reflected by the inner wall. It is. In this specification, the incident angle of light incident on an optical fiber is the angle formed by the central axis of the optical fiber and the light incident on the optical fiber.

As described above, the return light that is reflected by the workpiece or the like and propagates again from the output optical fiber toward the input optical fiber may leak in the case. However, in the above optical combiner, the energy of the light reflected by the inner wall of the case and re-entering the first input optical fiber is higher than the energy of the light reflected by the inner wall of the case and re-entering the second input optical fiber. is also small. By the way, when light beams having the same incident angle are separately incident on the first input optical fiber and the second input optical fiber, the first input optical fiber has a smaller NA of the light emitted from the output optical fiber. However, return light tends to enter more easily than the second input optical fiber having a large NA of the light emitted from the output optical fiber. In other words, in the optical combiner of the present invention, the energy of the light reflected by the inner wall of the case and re-entering the first input optical fiber is lower than that of the second input optical fiber. It is easier to enter than the two-input optical fiber. Therefore, the difference in the sum of the energy of the return light propagating from the output optical fiber and the energy of the light reflected and re-entering the case can be reduced between the first input optical fiber and the second input optical fiber. . For this reason, according to the optical combiner of the present invention, compared to the case where light with energy higher than that of the second input optical fiber is re-entered into the first input optical fiber in which the energy of the incident return light is high, the return light can suppress the influence of

Further, in a plane perpendicular to the longitudinal direction of the case, the reflectance of the inner wall on one side with respect to the area where the plurality of input optical fibers are arranged is and the first input optical fiber is arranged closer to the inner wall on the one side than the second input optical fiber.

By arranging the first input optical fiber on the inner wall side where the reflectance is lower than that of the second input optical fiber, it is possible to easily suppress the energy of the light re-entering the first input optical fiber.

In this way, when the reflectance of the inner wall on the one side is lower than the reflectance of the inner wall on the other side with reference to the area where the plurality of input optical fibers are arranged, the one side The inner wall of the is preferably transparent to at least part of the light.

Since the inner wall transmits at least part of the light, the energy of the light re-entering the first input optical fiber can be further suppressed.

Further, the inner wall on the one side of the case may be made of quartz, and the inner wall on the other side of the case may be made of metal.

Metal is preferably used for the case because it is easy to process and has excellent heat resistance, heat dissipation, and workability. On the other hand, metals generally have high light reflectance. Therefore, as described above, the inner wall on the other side of the case near the first input optical fiber is made of quartz having optical transparency, and the inner wall on the other side of the case near the second input optical fiber is made of metal. good too.

Alternatively, when the reflectance of the inner wall on the one side is lower than the reflectance of the inner wall on the other side with reference to the area where the plurality of input optical fibers are arranged, Preferably, the inner wall absorbs at least part of the light.

Since the inner wall absorbs at least part of the light, the energy of the light re-entering the first input optical fiber can be further suppressed.

In addition, in the plane perpendicular to the longitudinal direction of the case, the inner wall on one side with respect to the area where the plurality of input optical fibers are arranged diffusely reflects light, and the inner wall on the other side with respect to the area. The inner wall reflects light with less irregular reflection than the inner wall on the one side, and the first optical fiber for input is arranged closer to the inner wall on the one side than the second optical fiber for input. is preferred.

In general, the inner wall positioned closer to the first input optical fiber than the second input optical fiber diffusely reflects light, so that the energy density of the reflected light can be reduced. Therefore, the energy of the light re-entering the first input optical fiber can be further suppressed.

Further, in a plane perpendicular to the longitudinal direction of the case, the reflectance of the inner wall on one side with reference to the area where the plurality of input optical fibers are arranged, and the inner wall on the other side with reference to the area are equal to each other, and the distance from the first input optical fiber to the inner wall on the one side is preferably greater than the distance from the second input optical fiber to the inner wall on the other side.

In this case, the energy of the light reflected by the inner wall and re-entering the first input optical fiber can be suppressed without changing the reflectance between the inner wall on one side and the inner wall on the other side. Therefore, the structure of the case can be simplified as compared with the case where the reflectance is different between the inner wall on one side and the inner wall on the other side.

Further, the plurality of input fibers includes a specific input optical fiber, and the first input optical fiber and the second input optical fiber are arranged at positions sandwiching the specific input optical fiber. is preferred.

By sandwiching the specific input optical fiber, the specific input optical fiber becomes a barrier compared to the case where the specific input optical fiber is not sandwiched, and the second input optical fiber is used more than the first input optical fiber. It is possible to suppress the light reflected by the nearby inner wall from reentering the first input optical fiber. Therefore, it is possible to suppress the energy of the light re-entering the first input optical fiber.
The plurality of input optical fibers includes the specific input optical fiber, the first input optical fiber, and the second input optical fiber, and is arranged around the specific input optical fiber. It preferably consists of six optical fibers.

In this case, the specific input optical fiber and the input optical fibers arranged around the specific input optical fiber constitute seven input optical fibers, and the center-to-center distance between the adjacent input optical fibers is can be made equal. Also, a plurality of input optical fibers can be closely packed, and in this case, an increase in the size of the optical combiner can be suppressed.

The case has a first case portion in which grooves are formed and a second case portion in which grooves are formed, and the plurality of input optical fibers are arranged in the grooves of the first case portion. Preferably, the first case part is arranged in the groove of the second case part with the groove of the first case part facing the second case part.

In this case, a plurality of input optical fibers can be easily arranged in the tubular case. Further, when the first input optical fiber is arranged closer to the inner wall on one side than the second input optical fiber as described above, the positions of the first input optical fiber and the second input optical fiber The first input optical fiber and the second input optical fiber can be easily arranged in the case while maintaining the relationship. In addition, since it is easy to make the reflectance of the inner wall of the first case portion and the inner wall of the second case portion different as described above, the reflectance of the inner wall on one side and the The reflectance can be easily differentiated.

Preferably, the plurality of input optical fibers are fixed to the inner wall of the case with a light-transmissive resin.

By fixing a plurality of input optical fibers to the inner wall of the case, the position of each input optical fiber can be fixed. In addition, since the resin fixing the input optical fiber is light transmissive, it is possible to suppress heat generation and damage due to absorption of light leaked into the case by the resin.

Further, in order to solve the above-mentioned problems, a laser device according to the present invention includes any one of the optical combiners described above, and a plurality of light sources for inputting light into the respective input optical fibers. It is something to do.

As described above, according to the optical combiner, the sum of the energy of the return light propagating from the output optical fiber in the first input optical fiber and the energy of the light reflected and re-entering the case, and the second input light The difference between the energy of the return light propagating from the output optical fiber and the sum of the energy of the light reflected by the case and re-entering the fiber is reduced between the first input optical fiber and the second input optical fiber. can. Therefore, in a laser device using this optical combiner, it is possible to suppress the return light from entering a specific light source in a concentrated manner, thereby suppressing the influence of the return light.

Further, in order to solve the above problems, the present invention provides a method for manufacturing an optical combiner having an optical component in which one end of each of a plurality of input optical fibers is connected to an output optical fiber, the method comprising: a fiber determination step of determining the magnitude relationship of the NA of the two input optical fibers when light with the same incident angle is individually incident from the other end of the two input optical fibers in the optical fiber; an arranging step of arranging the optical component so that the side surfaces of the plurality of input optical fibers are surrounded in a case of the two input optical fibers determined in the fiber determination step in the arranging step When the input optical fiber with a smaller NA in the optical fiber is a first input optical fiber and the input optical fiber with a larger NA is a second input optical fiber, the first input light In the fiber, part of the light propagating from the output optical fiber toward the input optical fiber leaks and is reflected on the inner wall of the case, and the energy of the light re-entering the first input optical fiber is It is characterized in that the leaked light is arranged at a position where the energy is smaller than the energy of the light that is reflected by the inner wall and reenters the second input optical fiber.

According to the manufacturing method of such an optical combiner, the energy of the return light that propagates from the output optical fiber to the first input optical fiber and the energy of the return light that leaks from the optical parts in the case and is reflected on the inner wall of the case to the first input The total sum of the energy of the light re-entering the optical fiber for input, the energy of the return light propagating from the optical fiber for output to the second optical fiber for input, and the energy of the return light that leaks from the optical parts in the case and is reflected on the inner wall of the case It is possible to manufacture an optical combiner that can reduce the difference between the sum of the energy of the light re-entering the second input optical fiber and the energy of the light.

As described above, according to the present invention, an optical combiner, a laser device, and a method for manufacturing an optical combiner that can suppress the influence of return light are provided.

1 is a conceptual diagram showing a laser device according to a first embodiment of the present invention; FIG. 2 is an exploded view showing the optical combiner of FIG. 1; FIG. It is a figure which shows a mode that the 2nd case part was removed from the optical combiner of FIG. FIG. 4 is a cross-sectional view of the optical combiner at a position along line IV-IV of FIG. 3; FIG. 4 is a cross-sectional view along the central axis of the output optical fiber of the optical component; FIG. 4 is a diagram showing details of the arrangement of optical components; It is a flowchart which shows the manufacturing method of an optical combiner. It is a figure which shows the mode of a preparation process. It is a figure which shows the mode of a measurement process. It is a figure which shows the mode of an arrangement|positioning process. Figure 7 shows an optical combiner of a second embodiment of the invention in a manner similar to Figure 6; Figure 7 shows an optical combiner of a third embodiment of the invention in a manner similar to Figure 6; FIG. 5 is a diagram showing the relationship between the distance between the input optical fiber and the inner wall of the second case, and the power of light incident on the input optical fiber from the light source when a failure occurs. Figure 3 shows an optical combiner of a fourth embodiment of the invention in a manner similar to Figure 2; Figure 15 shows the optical component of Figure 14 in a manner similar to Figure 5;

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an optical combiner, a laser device, and a method for manufacturing an optical combiner according to the present invention will now be described in detail with reference to the drawings. The embodiments illustrated below are intended to facilitate understanding of the present invention, and are not intended to limit and interpret the present invention. The present invention can be modified and improved without departing from its spirit. Note that in the drawings referred to below, the dimensions of each member may be changed to facilitate understanding.

(First embodiment)
FIG. 1 is a conceptual diagram showing a laser device according to a first embodiment of the invention. As shown in FIG. 1, the laser device 100 of this embodiment mainly includes a plurality of light sources 10, a plurality of input optical fibers 20, an optical combiner 1, and a delivery optical fiber 40. As shown in FIG.

Each light source 10 is a laser device that emits light of a predetermined wavelength, and is, for example, a fiber laser device or a solid-state laser device. When the light source 10 is a fiber laser device, the light source 10 may be a resonator type fiber laser device or a MO-PA (Master Oscillator Power Amplifier) type fiber laser device. The light emitted from each light source 10 is, for example, light with a wavelength of 1070 nm. In this embodiment, seven light sources 10 are shown. Each light source 10 is connected to an input optical fiber 20 that propagates light emitted from the light source 10 . Therefore, the number of input optical fibers 20 is the same as the number of light sources 10 .

2 is an exploded view showing the optical combiner of FIG. 1; FIG. As shown in FIG. 2, the optical combiner 1 includes an optical component 2 and a case 3 as main components.

The case 3 consists of a first case portion 60 and a second case portion 70 .

The first case portion 60 is a member having a U-shaped cross section in which a groove 60G is formed. Specifically, side walls 62 are connected to both side edges of a flat bottom wall 61 perpendicularly to the bottom wall 61, and the bottom wall 61 and the side walls 62 form grooves 60G. is formed. The size of the groove 60G is set so that the optical component 2 can be accommodated therein. Each inner wall of the first case portion 60 forming the groove 60G is roughened by sandblasting or the like. Therefore, the light reflected by the inner wall of the first case portion 60 and the light transmitted through the inner wall of the first case portion 60 are scattered. In this embodiment, the first case portion 60 is made of quartz. Although different from the present embodiment, at least a portion of the inner walls of the first case portion 60 may not be roughened.

The second case portion 70 is a member having approximately the same length as the first case portion 60, and has a U-shaped cross section in which the groove 70G is formed. Specifically, side wall portions 72 are connected to both side edges of a flat bottom wall portion 71 perpendicularly to the bottom wall portion 71, and the bottom wall portion 71 and the side wall portions 72 form grooves 70G. forming The groove 70G is sized to accommodate the first case portion 60 . Specifically, the first case portion 60 is accommodated in the groove 70G of the second case portion 70 with the groove 60G of the first case portion 60 facing the bottom wall portion 71 side of the second case portion 70 . The distance between the surfaces of the pair of side wall portions 72 of the second case portion 70 facing inward is slightly larger than the distance between the surfaces of the side wall portions 62 of the first case portion 60 facing outward. The depth of the groove 70</b>G of the second case portion 70 is approximately equal to the height of the side wall portion 62 of the first case portion 60 . Therefore, when the first case portion 60 is accommodated in the groove of the second case portion 70 with the groove 60G of the first case portion 60 facing the bottom wall portion 71 side of the second case portion 70, the first case portion 60 is The outer surface of the bottom wall portion 61 of the portion 60 and the edges of the respective side wall portions 72 of the second case portion 70 are generally flush with each other. In this manner, the first case portion 60 is accommodated in the groove 70G of the second case portion 70, so that the first case portion 60 and the second case portion 70 form the tubular case 3. As shown in FIG. In addition, each inner wall of the second case portion 70 forming the groove 70G is generally flat. Therefore, light is likely to be reflected on the inner wall of the second case portion 70 . In this embodiment, the second case portion 70 is made of metal such as aluminum or brass.

The optical component 2 mainly includes the plurality of input optical fibers 20 , the tapered optical fiber 30 and the delivery optical fiber 40 .

The plurality of input optical fibers 20 are arranged in the optical combiner 1 such that six input optical fibers 20 surround one specific input optical fiber 20 . Therefore, in the present embodiment, the plurality of input optical fibers 20 have the same center-to-center distance in the optical combiner 1 . Further, in this embodiment, the input optical fibers 20 are arranged parallel to each other in the optical combiner 1 . Each of the input optical fibers 20 has a similar configuration, and has a core 21, a clad 22 surrounding the core 21, and a coating layer 23 covering the clad. higher than the refractive index. The core 21 is made of, for example, quartz doped with a dopant such as germanium (Ge) that increases the refractive index, and the cladding 22 is made of, for example, pure quartz. The refractive index of the core 21 may be higher than that of the clad 22. For example, the core 21 may be made of pure quartz, and a dopant such as fluorine (F) that lowers the refractive index of the clad 22 may be added. It may also consist of doped quartz. The input optical fiber 20 has, for example, a core 21 with a diameter of 10 μm and a clad 22 with an outer diameter of 125 μm. Each input optical fiber 20 is, for example, a single-mode fiber through which fundamental mode light mainly propagates, or a fu-mode fiber through which 2-3 mode light mainly propagates. The coating layer 23 is peeled off near one end of each input optical fiber 20 , and one end of each input optical fiber 20 is connected to one end of the tapered optical fiber 30 .

The tapered optical fiber 30 is an optical fiber whose outer diameter is not reduced at one end to which each input optical fiber 20 is connected, and whose outer diameter is reduced at the other end. Specifically, the tapered optical fiber 30 is integrally formed with a non-reduced diameter portion 33 that maintains a constant outer diameter at one end, and the outer diameter gradually decreases toward the other end. and a tapered portion 34 that is reduced in diameter. In this embodiment, the tapered optical fiber 30 does not particularly have a core-cladding structure, and the entire tapered optical fiber 30 is a portion capable of propagating light. The diameter of the non-reduced diameter portion 33 of the tapered optical fiber 30 is not particularly limited as long as the respective input optical fibers 20 can be connected, but is, for example, 450 μm, and the diameter at the other end is, for example, 100 μm. . Also, the length of the tapered portion 34 of the tapered optical fiber 30 is, for example, 30 mm.

It should be noted that the refractive index of the tapered optical fiber 30 is approximately equal to the refractive index of the core 21 of the input optical fiber 20. As will be described later, light is incident on the tapered optical fiber 30 from the input optical fiber 20. In this case, the reflection of light can be suppressed, which is preferable. The tapered optical fiber 30 may be made of, for example, quartz doped with a dopant such as germanium (Ge) to increase the refractive index, pure quartz, or quartz doped with a dopant such as fluorine (F). Moreover, the refractive index of the tapered optical fiber 30 may be different from the refractive index of the core 21 of the input optical fiber 20 .

The delivery optical fiber 40 has a core 41, a clad 42 surrounding the core 41, and a coating layer 43 covering the outer peripheral surface of the clad 42. The core 41 has a higher refractive index than the clad 42. ing. The refractive index of the core 41 is preferably equal to that of the tapered optical fiber 30 from the viewpoint of suppressing refraction of light incident from the tapered optical fiber 30 . Thus, for example, the core 41 consists of quartz doped with dopants such as germanium (Ge) to increase the refractive index, and the cladding 42 consists of pure quartz. The refractive index of the core 41 may be higher than that of the clad 42. For example, the core 41 may be made of pure quartz, and a dopant such as fluorine (F) that lowers the refractive index of the clad 42 may be added. It may also consist of doped quartz. In this embodiment, the diameter of the core 41 is greater than or equal to the diameter of the tapered optical fiber 30 at the other end. Therefore, as described above, when the diameter of the tapered optical fiber 30 is 100 μm at the other end, the diameter of the core 41 of the delivery optical fiber 40 is, for example, 100 μm. The coating layer 43 is removed near one end of the delivery optical fiber 40, and the core 41 at one end of the delivery optical fiber 40 and the other end of the tapered optical fiber 30 are connected to each other.

By connecting the core 21 of the input optical fiber 20 and the tapered optical fiber 30 and connecting the tapered optical fiber 30 and the core 41 of the delivery optical fiber 40 in this manner, the core 21 of the input optical fiber 20 and the tapered optical fiber 30 are connected. , the tapered optical fiber 30 and the core 41 of the delivery optical fiber 40 are optically coupled to each other. Therefore, the light incident on the tapered optical fiber 30 from the input optical fiber 20 can be emitted from the tapered optical fiber 30 , and the light emitted from the tapered optical fiber 30 can be emitted from the delivery optical fiber 40 . Further, it is also possible to grasp the tapered optical fiber 30 and the delivery optical fiber 40 as a unit. I can understand.

In this embodiment, the optical combiner 1 is assembled by placing the optical component 2 in the groove 60G of the first case portion 60 and placing the first case portion 60 in the groove 70G of the second case portion 70. ing. Details such as the arrangement of the optical component 2 will be described below.

FIG. 3 is a diagram showing how the second case part 70 is removed from the optical combiner 1 of FIG. As shown in FIG. 3, with the optical combiner 1 placed in the groove 60G of the first case portion 60, the plurality of input optical fibers 20 are fixed to the first case portion 60 by the light-transmissive first fixing member 81. As shown in FIG. fixed to the inner wall of the The first fixing member 81 covers the coating layer 23 of each of the input optical fibers 20 and the clad 22 exposed by peeling the coating layer 23, and holds the plurality of input optical fibers 20 in the first case portion. It is fixed at 60. Also, the first fixing member 81 is provided with a predetermined gap from the tapered optical fiber 30 . Therefore, each input optical fiber 20 is not fixed to the first case portion 60 by the first fixing member 81 in the vicinity of the connection to the tapered optical fiber 30 . Moreover, although it is preferable that the first fixing member 81 is fixed to the bottom wall portion 71 of the second case portion 70 , it does not have to be fixed to the bottom wall portion 71 of the second case portion 70 . It is preferable that the first fixing member 81 is made of a thermosetting resin from the viewpoint of suppressing positional displacement of the plurality of input optical fibers 20 due to heat.

Further, as shown in FIG. 3, in a state in which the optical combiner 1 is arranged in the groove 60G of the first case portion 60, the delivery optical fiber 40 is fixed to the first case portion 60 by the light-transmissive second fixing member 82. fixed to the inner wall. In this embodiment, the second fixing member 82 fixes the coating layer 43 of the delivery optical fiber 40 and the inner wall of the first case portion 60 . The second fixing member 82 is preferably made of a thermosetting resin like the first fixing member 81 from the viewpoint of suppressing positional displacement of the delivery optical fiber 40 due to heat. Also, the second fixing member 82 is preferably fixed to the bottom wall portion 71 of the second case portion 70 in the same manner as the first fixing member 81 , but is not fixed to the bottom wall portion 71 of the second case portion 70 . may

FIG. 4 is a cross-sectional view of the optical combiner 1 taken along line IV--IV of FIG. Note that FIG. 4 shows a state in which the second case portion 70 is not removed. As described above, the first case portion 60 and the second case portion 70 form the tubular case 3 . Therefore, the optical component 2 is surrounded by the case 3 , so that the sides of the plurality of input optical fibers 20 of the optical component 2 are surrounded by the case 3 . Further, the side surface of each side wall portion 62 of the first case portion 60 on the side opposite to the bottom wall portion 61 side and the surface of the bottom wall portion 71 of the second case portion 70 on the groove 70G side are bonded with an adhesive (not shown). Fixed. This adhesive is preferably a thermosetting resin from the viewpoint of suppressing the influence of heat.

Next, the numerical aperture (NA) of the light emitted from the delivery optical fiber 40 when the light is individually incident from each of the input optical fibers 20 will be described. The NA of the light emitted from the delivery optical fiber 40 positioned on the output end side of the output optical fiber 50 is the angle between the central axis of the core 41 of the delivery optical fiber 40 and the propagation direction of the light emitted from the delivery optical fiber 40. It is determined by the product n _out ×sin θ _out of the sine value of θ _out and the refractive index n _out of the core 41 of the delivery optical fiber 40 from which light is emitted. This angle θ _out is sometimes called the divergence angle. Therefore, if the beam quality is the same, the larger the spread of the emitted light, the larger the NA of the emitted light.

FIG. 5 is a cross-sectional view along the central axis of the output optical fiber 50 of the optical component 2. As shown in FIG. Note that hatching is omitted in FIG. 5 in order to avoid complication of the drawing. As indicated by the dashed line in FIG. 5, in this embodiment, the central axis of the tapered optical fiber 30 is the central axis 33C of the non-reduced diameter portion 33 including one end whose diameter is not reduced and the other end whose diameter is reduced. The center axis 34C of the tapered portion 34 including the is shifted. Specifically, the central axis 34C of the tapered portion 34 is inclined with respect to the central axis 33C of the non-reduced diameter portion 33 . Therefore, the center of the other end of the tapered optical fiber 30 is shifted in a predetermined radial direction with respect to the central axis 33C of the non-reduced diameter portion 33 of the tapered optical fiber 30 . Here, among the input optical fibers 20 shown in FIG. 5, the input optical fiber 20 positioned on the predetermined radial side with respect to the central axis 33C of the non-reduced diameter portion 33 of the tapered optical fiber 30 is the first input. The input optical fiber 20a located on the opposite side of the predetermined radial direction with respect to the central axis 33C is referred to as the second input optical fiber 20b. In this case, the amount of misalignment between the central axis of the core 21 of the first input optical fiber 20a and the central axis of the core 41 of the delivery optical fiber 40 is the same as the central axis of the core 21 of the second input optical fiber 20b and the delivery light. It is smaller than the amount of axial deviation from the central axis of the core 41 of the fiber 40 . At this time, when light with the same incident angle is incident on the first input optical fiber 20a and the second input optical fiber 20b, the light incident from the first input optical fiber 20a and emitted from the delivery optical fiber 40 is smaller than the NA of the light that enters from the second input optical fiber 20 b and exits from the delivery optical fiber 40 .

By arranging the first input optical fiber 20a and the second input optical fiber 20b as described above, the first input optical fiber 20a and the second input optical fiber 20b can be used as a plurality of input optical fibers. A specific input optical fiber 20 arranged at the center of the end face of the tapered optical fiber 30 of the optical fibers 20 for input is sandwiched.

Next, the details of the arrangement of the optical component 2 will be described. FIG. 6 is a diagram showing details of the arrangement of optical components. As shown in FIG. 6, in the present embodiment, in the plane perpendicular to the longitudinal direction of the case 3, the first case portion is located on one side with reference to the region AR indicated by the dotted line where the plurality of input optical fibers 20 are arranged. 60 is located, and the bottom wall portion 71 of the second case portion 70 is located on the other side with respect to the area AR. As described above, in this embodiment, the first case portion 60 is made of quartz, and the second case portion 70 is made of metal. Therefore, the inner wall on the other side of the case 3 with respect to the area AR tends to have a higher light reflectance than the inner wall on the one side. Further, as described above, the inner walls of the first case portion 60 are roughened to diffusely reflect light, and the inner walls of the second case portion 70 forming the grooves 70G are generally planar. Therefore, the inner wall of the second case portion 70 reflects light with less irregular reflection than the inner wall of the first case portion 60 . Therefore, even if the bottom wall portion 61 of the first case portion 60 and the bottom wall portion 71 of the second case portion 70 have the same reflectance, the energy of the light reflected by the bottom wall portion 61 of the first case portion 60 is The density tends to be lower than the energy density of light reflected by the bottom wall portion 71 of the second case portion 70 .

Further, in this embodiment, as shown in FIG. 6, the first input optical fiber 20a is positioned closer to the inner wall on one side than the second input optical fiber 20b, that is, near the bottom wall portion 61 of the first case portion 60. are placed. That is, the first input optical fiber 20a has a lower light reflectance than the second input optical fiber 20b, and is arranged near one inner wall of the first case portion 60 that diffusely reflects light. ing.

Next, operation of the laser device 100 will be described.

Each light source 10 injects light into the core 21 of the input optical fiber 20 . This light propagates through the core 21 of each input optical fiber 20 and exits from one end of the input optical fiber 20 . Light emitted from the input optical fiber 20 enters the tapered optical fiber 30 from one end of the tapered optical fiber 30 . The light incident on the tapered optical fiber 30 reaches the tapered portion 34 from the non-diameter-reduced portion 33 , and at the tapered portion 34 , at least part of the light propagates while being reflected by the outer peripheral surface of the tapered optical fiber 30 . The light propagating through the tapered portion 34 is emitted from the other end of the tapered optical fiber 30 , enters the core 41 of the delivery optical fiber 40 , and propagates through the delivery optical fiber 40 . The energy density of the light propagating through the core 41 of the delivery optical fiber 40 is preferably higher than the energy density of the light propagating through the core 21 of each input optical fiber 20, but it does not have to be higher. The light propagating through the delivery optical fiber 40 is emitted from the other end of the delivery optical fiber 40 and applied to an object to be irradiated such as a workpiece. The workpiece or the like is processed in this way.

Part of the light irradiated to the object to be irradiated may be reflected and enter the delivery optical fiber 40 again from the object to be irradiated. For example, when the object to be irradiated is a plate-shaped metal, the reflectance of the object to be irradiated is high at the initial stage when the light from the laser device 100 is irradiated. The intensity of incident light tends to be high. Therefore, there is a tendency for high-energy return light to be incident instantaneously in the initial stage when the object to be irradiated is irradiated with light.

The light that has entered the delivery optical fiber 40 enters the tapered optical fiber 30 from the delivery optical fiber 40 as return light, and then enters the respective input optical fibers 20 from the tapered optical fiber 30 . At this time, when light beams having the same incident angle are separately incident from the input optical fiber 20, the input optical fiber 20 that emits light with a smaller NA from the delivery optical fiber 40 tends to receive the return light more easily. Therefore, more return light is likely to enter the first input optical fiber 20a than the second input optical fiber 20b.

Also, at one end of the tapered optical fiber 30 to which the input optical fiber 20 is connected, part of the return light may leak from a portion to which the input optical fiber 20 is not connected. Furthermore, part of the light incident on the input optical fiber 20 may leak. Most of the light leaking from the input optical fiber 20 is light that has entered the clad 22 . The first fixing member 81 that fixes the input optical fiber 20 to the case 3 as described above is made of light-transmissive resin. Therefore, at least part of the light leaking from the optical component 2 propagates through the first fixing member 81 as indicated by the dashed line in FIG. Part of the light propagating through the first fixing member 81 is reflected by the inner wall of the first case portion 60 and the inner wall of the second case portion 70 , that is, the inner wall of the case 3 . At least part of the light reflected by the inner wall of the case 3 reenters the input optical fiber 20 . Another portion of the light leaking from the optical component 2 and propagating through the first fixing member 81 enters the first case portion 60, which is a light-transmitting member, from the first fixing member 81, The light is emitted from the case portion 60 to the outside of the optical combiner 1 .

As described above, in the present embodiment, the first input optical fiber 20a has a lower light reflectance than the second input optical fiber 20b and diffusely reflects light on one side of the inner wall of the first case portion 60. It is arranged near the bottom wall portion 61, and the second input optical fiber 20b is arranged relatively closer to the bottom wall portion 71 of the second case portion 70 than the first input optical fiber 20a. In other words, part of the light propagating from the output optical fiber 50 toward the input optical fiber 20 leaks from the first input optical fiber 20a and is reflected by the inner wall of the case 3 to reach the first input optical fiber 20a. It is arranged at a position where the energy of the re-entering light is smaller than the energy of the light re-entering the second input optical fiber 20b after the leaked light is reflected by the inner wall.

Therefore, the energy of the return light incident on the first input optical fiber 20 a from the tapered optical fiber 30 is higher than the energy of the return light incident on the second input optical fiber 20 b from the tapered optical fiber 30 , but the optical component 2 The energy of the light leaked from the first input optical fiber 20a and re-entering the first input optical fiber 20a is lower than the light energy of the leaked light re-entering the second input optical fiber 20b.

Next, the operation and effects of the optical combiner 1 and the laser device 100 of this embodiment will be described.

As described above, in the optical combiner 1 of the present embodiment, when light with the same incident angle is incident on the first input optical fiber 20a and the second input optical fiber 20b, The NA of the light that is incident and emitted from the optical fiber 50 for output is smaller than the NA of the light that is incident from the second optical fiber 20b for input and is emitted from the optical fiber 50 for output. Further, part of the light propagating from the output optical fiber 50 toward the input optical fiber 20 leaks from the first input optical fiber 20a and is reflected by the inner wall of the case 3 to the first input optical fiber 20a. It is arranged at a position where the energy of the light that re-enters is smaller than the energy of the light that the leaked light reflects off the inner wall of the case 3 and re-enters the second input optical fiber 20b.

The light emitted from the output optical fiber 50 may be reflected by a workpiece or the like and propagate again from the output optical fiber 50 toward the input optical fiber 20 , and this return light may leak inside the case 3 . be. However, in the above optical combiner 1, the energy of the light reflected by the inner wall of the case 3 and re-entering the first input optical fiber 20a is reflected by the inner wall of the case 3 and re-entering the second input optical fiber 20b. less than the energy of the light that By the way, when light beams having the same incident angle are separately incident on the first input optical fiber 20a and the second input optical fiber 20b, the NA of the light emitted from the output optical fiber 50 is small as described above. Return light tends to enter the first input optical fiber 20a more easily than the second input optical fiber 20b, in which the NA of the light emitted from the output optical fiber 50 is large. That is, in the optical combiner 1 of the present embodiment, the first input optical fiber 20a having a lower energy of the light reflected by the inner wall of the case 3 and re-entering than the second input optical fiber 20b includes the output optical fiber Light with energy higher than the energy of the return light entering the second input optical fiber 20b from 50 enters. Therefore, the difference in the sum of the energy of the return light propagating from the output optical fiber 50 and the energy of the light reflected by the case 3 and re-entering the first input optical fiber 20a and the second input optical fiber 20b is can be made smaller by For this reason, according to the optical combiner 1 of the present embodiment, compared to the case where light with energy higher than that of the second input optical fiber 20b is re-entered into the first input optical fiber 20a in which the energy of the incident return light is high. Therefore, the influence of returned light can be suppressed.

Therefore, in the laser device 100 including the optical combiner 1 and a plurality of light sources 10 for inputting light into the respective input optical fibers 20, the light source 10 to which the first input optical fiber 20a is connected and the second input optical fiber 20a are connected. Even when the return light propagates to the light source to which the optical fiber 20b is connected, it is possible to prevent a large amount of return light from entering one of the light sources 10 in a concentrated manner.

Further, in the optical combiner 1 of the present embodiment, in the plane perpendicular to the longitudinal direction of the case 3, the reflectance of the inner wall on one side with respect to the area AR where the plurality of input optical fibers 20 are arranged, that is, the first The reflectance of the inner wall of the case portion 60 is lower than the reflectance of the inner wall on the other side with respect to the area AR, that is, the reflectance of the inner wall of the second case portion 70. It is arranged closer to the inner wall on one side than the input optical fiber 20b. Therefore, the energy of the light re-entering the first input optical fiber 20a can be easily suppressed.

Furthermore, in the optical combiner 1 of the present embodiment, the inner wall on the one side, which is the inner wall of the first case portion 60, transmits at least part of the light. Therefore, the energy of the light re-entering the first input optical fiber 20a can be further suppressed.

In addition, in the optical combiner 1 of the present embodiment, the inner wall on one side, which is the inner wall of the first case portion 60, diffusely reflects light, and the inner wall on the other side with respect to the area AR, which is the inner wall of the second case portion 70, is The first input optical fiber 20a is arranged closer to the one-side inner wall than the second input optical fiber 20b. Therefore, the energy density of the light reflected by the inner wall on one side can be reduced, so that the energy of the light re-entering the first input optical fiber 20a can be further suppressed.

Moreover, in the optical combiner 1 of this embodiment, the second case portion 70 of the case 3 is made of metal. Metal is easy to work and has excellent heat resistance and workability, so it is easy to use for the case. Also, since metal has excellent thermal conductivity, heat can be easily dissipated through the second case portion 70 .

In addition, in the optical combiner 1 of the present embodiment, the first input optical fiber 20a and the second input optical fiber 20b are arranged at positions sandwiching the specific input optical fiber 20 therebetween. Therefore, compared to the case where the specific input optical fiber 20 is not sandwiched, the specific input optical fiber 20 becomes a barrier, and the light is reflected by the inner wall closer to the second input optical fiber 20b than the first input optical fiber 20a. It is possible to suppress re-entering the first input optical fiber 20a. Therefore, it is possible to suppress the energy of the light re-entering the first input optical fiber 20a.

Furthermore, in the optical combiner 1 of the present embodiment, the plurality of input optical fibers 20 includes a specific input optical fiber 20, a first input optical fiber 20a, and a second input optical fiber 20b. and six optical fibers arranged around the optical fiber 20 . Therefore, the specific input optical fiber 20 and the input optical fibers 20 arranged around the specific input optical fiber 20 constitute seven input optical fibers 20, and the input optical fibers 20 adjacent to each other The center-to-center distances can be made equal.

In addition, when six input optical fibers 20 surround one specific input optical fiber 20, if the adjacent input optical fibers 20 are in contact with each other, the plurality of input optical fibers 20 are Close packed. In this case, the optical combiner 1 can be miniaturized.

Further, in the optical combiner 1 of the present embodiment, the plurality of input optical fibers 20 are arranged in the grooves 60G of the first case portion 60, and the grooves 60G of the first case portion 60 are arranged in the first case portion 60. It is arranged in the groove 70G of the second case portion 70 so as to face the second case portion 70 side. Therefore, compared to the case where the case 3 is not divided into the first case portion 60 and the second case portion 70, the plurality of input optical fibers 20 can be easily arranged in the tubular case 3. Further, when the first input optical fiber 20a is arranged closer to the inner wall on one side than the second input optical fiber 20b as described above, the first input optical fiber 20a and the second input optical fiber The first input optical fiber 20a and the second input optical fiber 20b can be easily arranged in the case 3 while maintaining the positional relationship with the input optical fiber 20b. Further, as described above, it is easy to make the reflectance of the inner wall of the first case portion 60 and the inner wall of the second case portion 70 different. can be easily made different from the reflectance of

In the optical combiner 1 of this embodiment, the plurality of input optical fibers 20 are fixed to the inner wall of the case 3 by the first fixing member 81 made of light-transmitting resin. Therefore, the position of each input optical fiber 20 can be fixed, and it is possible to suppress heat generation and damage due to absorption of light leaked into the case 3 by the resin.

Next, a method for manufacturing the optical combiner 1 of this embodiment will be described.

FIG. 7 is a flow chart showing a method for manufacturing the optical combiner 1 of this embodiment. As shown in FIG. 7, the method for manufacturing the optical combiner 1 of this embodiment includes a preparation process PS1, a fiber determination process PS2, and an arrangement process PS3.

<Preparation process PS1>
This step is a step of preparing the optical component 2 in which one end of each of the plurality of input optical fibers 20 is connected to the output optical fiber 50 . FIG. 8 is a diagram showing the state of this step. First, a plurality of input optical fibers 20, tapered optical fibers 30, and delivery optical fibers 40 are prepared. The coating layer 23 near one end of each input optical fiber 20 is removed. The tapered optical fiber 30 is formed by, for example, preparing an optical fiber having the diameter of the non-reduced diameter portion 33 and having no clad, and forming the tapered portion 34 by melting and drawing a part of the optical fiber. Obtainable. Also, the coating layer 43 near one end of the delivery optical fiber 40 is removed.

Then, as shown in FIG. 8, one ends of the plurality of input optical fibers 20 from which the coating layer 23 has been stripped are connected to one end of the tapered optical fiber 30 . One end of the tapered optical fiber 30 is the end on the side of the non-reduced diameter portion 33 . Also, one end of the delivery optical fiber 40 from which the coating layer 43 has been stripped is connected to the other end of the tapered optical fiber 30 . The other end of the tapered optical fiber 30 is the end on the tapered portion 34 side. The output optical fiber 50 is formed by connecting the tapered optical fiber 30 and the delivery optical fiber 40 . Either the connection between the input optical fiber 20 and the tapered optical fiber 30 or the connection between the tapered optical fiber 30 and the delivery optical fiber 40 may be performed first. Moreover, the connection is preferably performed by fusion. Thus, the optical component 2 shown in FIG. 2 is prepared.

It should be noted that this process described above is an example, and may be prepared in any way as long as the optical component 2 shown in FIG. 2 is prepared. For example, this step may be performed by purchasing the optical component 2 shown in FIG.

<Fiber Judgment Process PS2>
This step determines the magnitude relationship of the NA of two input optical fibers when light beams having the same incident angle are individually incident from the other ends of two input optical fibers in a plurality of input optical fibers. It is a process. It is only necessary to determine the magnitude relationship between the NAs of the two input optical fibers, and this step includes a measurement step PS2a and a comparison step PS2b. Note that this step may be performed by another method that does not include at least one of the measurement step PS2a and the comparison step PS2b described below.

<Measurement process PS2a>
This step is a step of individually inputting light beams having the same incident angle from the other end of each input optical fiber 20 of the optical component 2 and measuring the spread of each light beam emitted from the output optical fiber 50 . FIG. 9 is a diagram showing the state of this process. In this step of the present embodiment, the other end of one optical fiber 20 for input is fused to the end of the optical fiber 91f, which is the light emitting end of the light source 91 for testing. Next, light with a predetermined wavelength and a predetermined number of modes, that is, light with a predetermined beam quality is emitted from the test light source 91 . The test light source 91 individually enters light having the same wavelength and the same number of modes into each of the input optical fibers 20 at the same incident angle. Then, the diameter of light emitted from the delivery optical fiber 40 is measured. The test light source 91 is not particularly limited as long as it is a light source that emits a predetermined beam quality. In this embodiment, the test light source 91 includes a light source 92 such as an ASE (Amplified Spontaneous Emission) light source or an SLD (Super-Luminescent Diode) light source, and a plurality of optical fibers 93 and 94 are connected to this light source. The plurality of optical fibers 93 and 94 differ from each other in at least one of the core diameter and the refractive index difference of the core with respect to the cladding. Therefore, the light emitted from the optical fiber 91f has a predetermined beam quality as described above. For this measurement, for example, a power meter 95 shown in FIG. 9 can be used. The power meter 95 is irradiated with light emitted from the delivery optical fiber 40, and the average radius of the area including the center where the integrated value of the power of the light is 1/e of the power of the entire light is measured. This measurement is performed for each input optical fiber 20 . As described above, when the spread of the light emitted from the output optical fiber 50 is large, the NA of the light emitted from the output optical fiber 50 is large. Therefore, in the above measurement, if the diameter of the light having a predetermined power or more received by the power meter 95 is large, it can be evaluated that the NA of the light is large. It is preferable that the delivery optical fiber 40 is provided with a cladding mode stripper for removing cladding mode light during measurement.

In this embodiment, the power meter 95 is used to measure the spread of each light emitted from the output optical fiber 50. may measure the spread of light. For example, a measuring instrument capable of measuring the divergence angle of each light emitted from the output optical fiber 50 may be used.

Also, in this step, light beams having the same incident angle were separately incident from the other ends of the input optical fibers 20 of the optical components 2, and the spread of the light beams emitted from the output optical fibers 50 was measured. However, it suffices to input light beams having the same incident angle from the other end of two or more input optical fibers 20 of the optical component 2 and measure the spread of each light beam emitted from the output optical fiber 50 . , all input optical fibers 20 need not be measured.

<Comparison step PS2b>
This step is a step of comparing the spread of each light measured in the measurement step PS2a. In this embodiment, among the two input optical fibers 20 among the plurality of input optical fibers 20, the input optical fiber 20 with a smaller spread of light is used as the first input optical fiber 20a, and the input with a large spread is used. The optical fiber 20 for input is referred to as a second input optical fiber 20b. The first input optical fiber 20a is preferably the input optical fiber 20 with the smallest spread of light among the plurality of input optical fibers 20 . As described in the measurement step PS2a, if the spread of the light emitted from the output optical fiber 50 is large in the measurement step PS2a of the present embodiment, the NA of the light emitted from the output optical fiber 50 is large. It is the same to compare the spread of the respective light beams and to compare the NA of the light beams emitted from the output optical fiber 50 . Therefore, when light with the same incident angle is separately incident from the other end of the first input optical fiber 20a and the second input optical fiber 20b, which are two input optical fibers in a plurality of input optical fibers, The magnitude relationship between the NAs of the first input optical fiber 20a and the second input optical fiber 20b is determined.

<Placement process PS3>
This step is a step of arranging the optical component 2 so that the side faces of the plurality of input optical fibers 20 are surrounded in the tubular case 3 . FIG. 10 is a diagram showing the state of this step. Prior to this step, first, the first case portion 60 and the second case portion 70 are prepared. This preparation may be performed in the preparation step PS1. First, one end sides of the plurality of input optical fibers 20 , the tapered optical fiber 30 , and the one end side of the delivery optical fiber 40 are arranged in the groove 60</b>G of the first case portion 60 . As described above, the inner wall of the first case portion 60 transmits part of the light incident on the inner wall and irregularly reflects another part of the incident light. Therefore, the optical component 2 is arranged in the groove 60G so that the first input optical fiber 20a is closer to the bottom wall portion 61 of the first case portion 60 than the second input optical fiber 20b.

Then, the first fixing member 81 and the second fixing member 82 are filled and solidified as shown in FIG. If the first fixing member 81 and the second fixing member 82 are thermosetting resin, the resin is cured by heating. to cure the resin.

Next, an adhesive is applied to the side surface of the side wall portion 62 of the first case portion 60 opposite to the bottom wall portion 61 side, and the first case portion 60 is arranged in the groove 70G of the second case portion 70. , to solidify the adhesive. This adhesive is preferably a thermosetting resin. In this embodiment, since the first case portion 60 is optically transparent, the adhesive may be photocurable.

In addition, unlike the above, after the first fixing member 81 and the second fixing member 82 are filled as shown in FIG. 3, the adhesive is applied before the first fixing member 81 and the second fixing member 82 are solidified. Then, the first case portion 60 is arranged in the groove 70G of the second case portion 70, and then the adhesive and the first fixing member 81 and the second fixing member 82 are solidified. In this case, the first fixing member 81 and the second fixing member 82 can also be fixed to the second case portion 70 .

In this manner, the first case portion 60 and the second case portion 70 are fixed to each other to form the tubular case 3 . As described above, since the first input optical fiber 20a is arranged closer to the bottom wall portion 61 of the first case portion 60 than the second input optical fiber 20b is, the second input optical fiber 20b is arranged relatively closer to the bottom wall portion 71 of the second case portion 70 than the first input optical fiber 20a. Furthermore, the inner wall of the first case portion 60 has a lower light reflectance than the inner wall of the second case portion 70, and diffusely reflects light. That is, in this step, the input optical fiber with the smaller NA among the two input optical fibers determined in the fiber determination step PS2 is taken as the first input optical fiber 20a, and the input optical fiber with the larger NA is taken as the first input optical fiber 20a. When the second input optical fiber 20b is used, part of the light propagating from the output optical fiber 50 toward the input optical fiber 20 leaks in the case 3 from the first input optical fiber 20a. The energy of the light reflected by the inner wall of the case 3 and re-entering the first input optical fiber 20a is greater than the energy of the light reflected by the inner wall of the case 3 and re-entering the second input optical fiber 20b. The first input optical fiber 20a is arranged at the position where the distance between the two is smaller.

Thus, the optical combiner 1 is manufactured.

According to the method of manufacturing the optical combiner 1 of the present embodiment, the energy of the return light that propagates from the output optical fiber 50 to the first input optical fiber 20a and the energy of the return light that leaks from the optical component 2 in the case 3 and the inner wall of the case 3 , and the energy of the return light propagating from the output optical fiber 50 to the second input optical fiber 20b and the optical component in the case 3 2, reflected on the inner wall of the case 3, and re-entering the second input optical fiber 20b. Therefore, the optical combiner 1 manufactured by the manufacturing method of this embodiment can suppress the influence of return light.

(Second embodiment)
Next, a second embodiment of the invention will be described in detail with reference to FIG. Constituent elements that are the same as or equivalent to those of the first embodiment are denoted by the same reference numerals, and overlapping descriptions will be omitted unless specifically described.

FIG. 7 shows the optical combiner of the present embodiment in a manner similar to that of FIG. 6; The optical combiner 1 of the present embodiment differs from the optical combiner 1 of the first embodiment in that the inner wall of the first case portion 60 is processed to be light absorbing. Therefore, the inner wall of the first case portion 60 has a lower light reflectance than the inner wall of the second case portion 70 . In this embodiment, the first case portion 60 is made of metal. For example, the first case portion 60 is made of aluminum, and the inner wall of the first case portion 60 is black anodized. Note that unlike the present embodiment, the first case portion 60 may be made of a material other than metal, and the inner wall of the first case portion 60 may be processed to be light absorbing. However, it is preferable that the first case portion 60 is made of metal from the viewpoint of easily releasing heat generated from the absorbed light to the outside.

In the optical combiner 1 of the present embodiment, the reflectance of the inner wall on one side with reference to the area AR where the plurality of input optical fibers 20 are arranged is higher than the reflectance of the inner wall on the other side with the area AR as a reference. The low, one-sided inner wall absorbs at least a portion of the leaked light. Therefore, the energy of the light re-entering the first input optical fiber 20a can be further suppressed.

The optical combiner 1 of this embodiment is manufactured in the same manner as the optical combiner 1 of the first embodiment.

(Third embodiment)
Next, a third embodiment of the present invention will be described in detail with reference to FIGS. 12 and 13. FIG. Constituent elements that are the same as or equivalent to those of the second embodiment are denoted by the same reference numerals, and overlapping descriptions will be omitted unless specifically described.

FIG. 12 is a diagram showing the optical combiner of this embodiment in a manner similar to that of FIG. As shown in FIG. 6, the optical combiner 1 of the present embodiment has the same light reflectance of the inner wall of the first case portion 60 and the inner wall of the second case portion 70. It differs from the optical combiner 1 of the second embodiment. That is, in the optical combiner 1 of the present embodiment, in the plane perpendicular to the longitudinal direction of the case 3, the reflectance of the inner wall on one side with respect to the area AR where the plurality of input optical fibers 20 are arranged, and the area The reflectance of the inner wall on the other side with respect to AR is equal to each other, and the first input optical fiber 20a is arranged closer to the inner wall on the one side than the second input optical fiber 20b. Furthermore, in the optical combiner 1 of this embodiment, the distance from the first input optical fiber 20a to the inner wall on one side is greater than the distance from the second input optical fiber 20b to the inner wall on the other side.

When the leaked light reflected by the inner wall of the case 3 reenters the input optical fiber 20, the input optical fiber 20 is more likely to reach the input optical fiber 20 when the distance between the input optical fiber 20 and the inner wall facing the input optical fiber 20 is greater. It is difficult for the leaked light reflected by the inner wall of the case 3 to enter again. This will be explained using FIG. FIG. 13 shows the distance d between the input optical fiber 20 and the inner wall of the second case portion 70 shown in FIG. 6 of the first embodiment, and the power of light incident on the input optical fiber 20 from the light source 10 when a failure occurs. It is a figure which shows the relationship with. As described in the first embodiment, the inner wall of the first case portion 60 has a low light reflectance and diffusely reflects light. Therefore, the light leaked in the case 3 has a large effect on the light reflected by the inner wall of the second case portion 70 and reentering the input optical fiber 20 . Therefore, referring to FIG. 13, the smaller the distance d between the input optical fiber 20 and the inner wall of the second case portion 70, the smaller the power of the light incident on the input optical fiber 20 from the light source 10 when a failure occurs. . The fact that the power of the light incident on the input optical fiber 20 from the light source 10 is small means that the power of the return light that is reflected by the workpiece or the like and enters the output optical fiber 50 is also small. The power of the emitted light is also small. Therefore, when the distance d between the input optical fiber 20 and the inner wall of the second case portion 70 is small, failure tends to occur even if the power of the light leaked in the case 3 is small. Therefore, if the distance d between the input optical fiber 20 and the inner wall of the second case portion 70 is large, the influence of the returned light is small. The reason for this is that the larger the distance d between the input optical fiber 20 and the inner wall of the second case portion 70, the more difficult it is for the leaked light reflected by the inner wall of the second case portion 70 to enter the input optical fiber 20 again. it is conceivable that.

Therefore, in the present embodiment, as described above, in the optical combiner 1, the reflectance of the inner wall on one side and the reflectance of the inner wall on the other side with respect to the area AR are equal to each other, and the first input optical fiber 20a to the inner wall on one side is longer than the distance from the second input optical fiber 20b to the inner wall on the other side. Therefore, the energy of the leaked light reflected by Case 3 and re-entering the first input optical fiber 20a is lower than the energy of the leaked light reflected by Case 3 and re-entering the second input optical fiber 20b. .

According to the optical combiner 1 of the present embodiment, the energy of the light reflected by the inner wall and re-entering the first input optical fiber 20a is suppressed without changing the reflectance between the inner wall on one side and the inner wall on the other side. can do. Therefore, the configuration of the case 3 can be simplified as compared with the case where the inner wall on one side and the inner wall on the other side have different reflectances.

The optical combiner 1 of this embodiment is manufactured by the same steps as the manufacturing method of the first embodiment shown in the flowchart of FIG. However, in the method for manufacturing the optical combiner 1 of the present embodiment, in the disposing step PS3, the distance from the first input optical fiber 20a to the inner wall of the first case portion 60 is set to the second input optical fiber 20b to the second case portion. The optical component 2 is arranged so that it is greater than the distance to the inner wall of 70 .

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described in detail with reference to FIGS. 14 and 15. FIG. Constituent elements that are the same as or equivalent to those of the first embodiment are denoted by the same reference numerals, and overlapping descriptions will be omitted unless specifically described.

FIG. 14 is a diagram showing the optical combiner 1 of this embodiment in the same manner as in FIG. As shown in FIG. 14, the optical combiner 1 of this embodiment mainly differs from the optical combiner 1 of the first embodiment in that the optical component 2 does not have the tapered optical fiber 30 . Therefore, the delivery optical fiber 40 becomes the output optical fiber 50 . In this embodiment, each input optical fiber 20 is connected to one end of the delivery optical fiber 40, and the core 41 of the delivery optical fiber 40 and the core 21 of each input optical fiber 20 are optically coupled. ing. Therefore, the diameter of the clad 42 of the delivery optical fiber 40 of the present embodiment is, for example, equal to the diameter of one end of the tapered optical fiber 30 of the first embodiment to which the respective input optical fibers 20 are connected. Also, the diameter of the core 41 of the delivery optical fiber 40 of the present embodiment is equal to or greater than the diameter of the circle surrounding the core 21 of each input optical fiber 20 .

FIG. 15 shows the optical component 2 of FIG. 14 in a manner similar to that of FIG. As shown in FIG. 15, in the optical combiner 1 of this embodiment, the longitudinal direction of the first input optical fiber 20a and the longitudinal direction of the delivery optical fiber 40 are substantially parallel, but the longitudinal direction of the second input optical fiber 20b is substantially parallel to the longitudinal direction of the delivery optical fiber 40. The longitudinal direction and the longitudinal direction of the delivery optical fiber 40 are non-parallel. That is, the parallelism between the longitudinal direction of the first input optical fiber 20a and the longitudinal direction of the delivery optical fiber 40 is higher than the parallelism between the longitudinal direction of the second input optical fiber 20b and the longitudinal direction of the delivery optical fiber 40. high.

When the first input optical fiber 20a and the second input optical fiber 20b are connected to the delivery optical fiber 40 in this manner, the same incident light is individually transmitted from the first input optical fiber 20a and the second input optical fiber 20b. When light with an angle is incident, the NA of the light that is incident from the first input optical fiber 20a and is emitted from the delivery optical fiber 40 is greater than the NA of the light that is incident from the second input optical fiber 20b and is emitted from the delivery optical fiber 40. also becomes smaller.

Therefore, also in this embodiment, the first input optical fiber 20a is arranged closer to the bottom wall portion 61 of the first case portion 60 than the second input optical fiber 20b, and the second input optical fiber 20b is arranged closer to the bottom wall portion 71 of the second case portion 70 than the first input optical fiber 20a.

In this embodiment, light is condensed from the core 21 of each input optical fiber 20 to the core 41 of the delivery optical fiber 40, but the energy density of the light propagating through the core 41 of the delivery optical fiber 40 is It may be lower than the energy density of light propagating through the core 21 of each input optical fiber 20 .

Since the optical combiner 1 of this embodiment does not include the tapered optical fiber 30, the configuration can be simplified.

The optical combiner 1 of this embodiment is manufactured by the same steps as the manufacturing method of the first embodiment shown in the flowchart of FIG. However, in the manufacturing method of the optical combiner 1 of this embodiment, each input optical fiber 20 is directly connected to the delivery optical fiber 40 in the preparatory step PS1.

Although the present invention has been described above using the embodiments as examples, the present invention is not limited to these.

For example, in the above-described embodiment, in the tapered optical fiber 30, the central axis 33C of the non-reduced diameter portion 33 including one end whose diameter is not reduced and the central axis 34C of the tapered portion 34 including the other end whose diameter is reduced are misaligned. rice field. However, in the tapered optical fiber 30, the central axis 33C of the non-reduced diameter portion 33 and the central axis 34C of the tapered portion 34 may coincide. That is, the tapered optical fiber 30 may have a completely rotationally symmetrical shape about the axis. In this case, the parallelism between the central axis of the first input optical fiber 20a and the central axis of the tapered optical fiber 30 is higher than the parallelism between the central axis of the second input optical fiber 20b and the central axis of the tapered optical fiber 30. is also raised. Even in this case, when light with the same incident angle is separately incident on the first input optical fiber 20a and the second input optical fiber 20b, the delivery light is incident from the first input optical fiber 20a. The NA of the light emitted from the fiber 40 is made smaller than the NA of the light emitted from the delivery optical fiber 40 after entering from the second input optical fiber 20b. That is, in the present invention, when light beams having the same incident angle are separately incident on the first input optical fiber 20a and the second input optical fiber 20b, the light is incident from the first input optical fiber 20a and delivered to the delivery optical fiber. If the NA of the light emitted from 40 is made smaller than the NA of the light that enters from the second input optical fiber 20b and is emitted from the delivery optical fiber 40, it can be appropriately modified in connection between the optical fibers. .

Moreover, the delivery optical fiber 40 is not essential in the first to third embodiments. In this case, the tapered optical fiber 30 becomes the output optical fiber.

Also, the plurality of input optical fibers 20 of the optical combiner 1 of the present invention may be less than seven as long as they include the first input optical fiber 20a and the second input optical fiber 20b. It may well be eight or more.

Further, the case 3 of the optical combiner 1 of the present embodiment is composed of the first case portion 60 and the second case portion 70, but any tubular case may be used and may be composed of one member.

Also, in the above embodiment, the optical component 2 is fixed to the case 3 by the first fixing member 81 and the second fixing member 82, but the optical component 2 may be fixed to the case 3 by another method.

INDUSTRIAL APPLICABILITY According to the present invention, an optical combiner, a laser device, and a method for manufacturing an optical combiner capable of suppressing the influence of return light are provided, and can be used for processing laser devices, medical laser devices, and the like.

Reference Signs List 1 optical combiner 2 optical component 3 case 10 light source 20 input optical fiber 21 core 22 clad 30 tapered optical fiber 33 Non-reduced diameter portion 34 Tapered portion 40 Delivery optical fiber 41 Core 42 Clad 50 Output optical fiber 60 First case portion 70 Second Case part 100 ... laser device

Claims (19)

a plurality of input optical fibers including a first input optical fiber and a second input optical fiber;
an output optical fiber to which one end of each of the plurality of input optical fibers is connected;
a tubular case surrounding the sides of the plurality of input optical fibers;
with
When light with the same incident angle is incident on the first optical fiber for input and the second optical fiber for input individually, the amount of light incident from the first optical fiber for input and emitted from the optical fiber for output is NA is smaller than the NA of light incident from the second optical fiber for input and emitted from the optical fiber for output;
A part of the light propagating from the output optical fiber toward the input optical fiber leaks from the first input optical fiber, is reflected by the inner wall of the case, and is re-entered into the first input optical fiber. is arranged at a position where the energy of the light that leaks is smaller than the energy of the light that reenters the second input optical fiber after the leaked light is reflected by the inner wall ;
In the plane perpendicular to the longitudinal direction of the case, the reflectance of the inner wall on one side with respect to the area where the plurality of input optical fibers are arranged is the reflectance of the inner wall on the other side with respect to the area. ratio, and the first input optical fiber is positioned closer to the inner wall on the one side than the second input optical fiber
An optical combiner characterized by: a plurality of input optical fibers including a first input optical fiber and a second input optical fiber;
an output optical fiber to which one end of each of the plurality of input optical fibers is connected;
a tubular case surrounding the sides of the plurality of input optical fibers;
with
When light with the same incident angle is incident on the first optical fiber for input and the second optical fiber for input individually, the amount of light incident from the first optical fiber for input and emitted from the optical fiber for output is NA is smaller than the NA of light incident from the second optical fiber for input and emitted from the optical fiber for output;
A part of the light propagating from the output optical fiber toward the input optical fiber leaks from the first input optical fiber, is reflected by the inner wall of the case, and is re-entered into the first input optical fiber. is arranged at a position where the energy of the light that leaks is smaller than the energy of the light that reenters the second input optical fiber after the leaked light is reflected by the inner wall ;
In a plane perpendicular to the longitudinal direction of the case, the inner wall on one side with respect to the region where the plurality of input optical fibers are arranged diffusely reflects light, and the inner wall on the other side with respect to the region Light is reflected with less diffuse reflection than the inner wall on the one side, and the first optical fiber for input is arranged closer to the inner wall on the one side than the second optical fiber for input.
An optical combiner characterized by: In the plane perpendicular to the longitudinal direction of the case, the reflectance of the inner wall on one side with respect to the area where the plurality of input optical fibers are arranged is the reflectance of the inner wall on the other side with respect to the area. 3. The optical combiner of claim 2 , wherein the first input optical fiber is located closer to the one inner wall than the second input optical fiber. 4. The optical combiner according to claim 1 , wherein said one inner wall transmits at least part of light. 5. The optical combiner according to claim 4 , wherein the inner wall on the one side of the case is quartz and the inner wall on the other side of the case is metal. 4. The light combiner according to claim 1 , wherein said one inner wall absorbs at least part of light. a plurality of input optical fibers including a first input optical fiber and a second input optical fiber;
an output optical fiber to which one end of each of the plurality of input optical fibers is connected;
a tubular case surrounding the sides of the plurality of input optical fibers;
with
When light with the same incident angle is incident on the first optical fiber for input and the second optical fiber for input individually, the amount of light incident from the first optical fiber for input and emitted from the optical fiber for output is NA is smaller than the NA of light incident from the second optical fiber for input and emitted from the optical fiber for output;
A part of the light propagating from the output optical fiber toward the input optical fiber leaks from the first input optical fiber, is reflected by the inner wall of the case, and is re-entered into the first input optical fiber. is arranged at a position where the energy of the light that leaks is smaller than the energy of the light that reenters the second input optical fiber after the leaked light is reflected by the inner wall ;
The plurality of input optical fibers includes a specific input optical fiber,
The first input optical fiber and the second input optical fiber are arranged at positions sandwiching the specific input optical fiber.
An optical combiner characterized by: In the plane perpendicular to the longitudinal direction of the case, the reflectance of the inner wall on one side with respect to the area where the plurality of input optical fibers are arranged is the reflectance of the inner wall on the other side with respect to the area. 8. The optical combiner of claim 7 , wherein the first input optical fiber is located closer to the one inner wall than the second input optical fiber. 9. The light combiner of claim 8 , wherein the inner wall on one side transmits at least a portion of light. 10. The optical combiner of claim 9 , wherein the inner wall on the one side of the case is quartz and the inner wall on the other side of the case is metal. 9. The light combiner of claim 8 , wherein the inner wall on one side absorbs at least part of the light. In a plane perpendicular to the longitudinal direction of the case, the inner wall on one side with respect to the region where the plurality of input optical fibers are arranged diffusely reflects light, and the inner wall on the other side with respect to the region Light is reflected with less diffuse reflection than the inner wall on the one side, and the first optical fiber for input is arranged closer to the inner wall on the one side than the second optical fiber for input. 12. An optical combiner according to any one of claims 7-11 . In a plane perpendicular to the longitudinal direction of the case, the reflectance of the inner wall on one side with reference to the area where the plurality of input optical fibers are arranged, and the reflection of the inner wall on the other side with reference to the area are equal to each other,
8. The optical combiner according to claim 7 , wherein the distance from the first input optical fiber to the inner wall on the one side is longer than the distance from the second input optical fiber to the inner wall on the other side. . The plurality of input optical fibers are six including the specific input optical fiber, the first input optical fiber and the second input optical fiber and arranged around the specific input optical fiber. 14. An optical combiner according to claim 7 or 13 , comprising: an optical fiber of a plurality of input optical fibers including a first input optical fiber and a second input optical fiber;
an output optical fiber to which one end of each of the plurality of input optical fibers is connected;
a tubular case surrounding the sides of the plurality of input optical fibers;
with
When light with the same incident angle is incident on the first optical fiber for input and the second optical fiber for input individually, the amount of light incident from the first optical fiber for input and emitted from the optical fiber for output is NA is smaller than the NA of light incident from the second optical fiber for input and emitted from the optical fiber for output;
A part of the light propagating from the output optical fiber toward the input optical fiber leaks from the first input optical fiber, is reflected by the inner wall of the case, and is re-entered into the first input optical fiber. is arranged at a position where the energy of the light that leaks is smaller than the energy of the light that reenters the second input optical fiber after the leaked light is reflected by the inner wall ;
In a plane perpendicular to the longitudinal direction of the case, the reflectance of the inner wall on one side with reference to the area where the plurality of input optical fibers are arranged, and the reflection of the inner wall on the other side with reference to the area are equal to each other,
The distance from the first input optical fiber to the inner wall on the one side is greater than the distance from the second input optical fiber to the inner wall on the other side.
An optical combiner characterized by: The case has a first case portion in which a groove is formed and a second case portion in which a groove is formed,
The plurality of input optical fibers are arranged in the groove of the first case,
16. The first case part is arranged in the groove of the second case part with the groove of the first case part facing the second case part. or the optical combiner according to claim 1. 17. The optical combiner according to any one of claims 1 to 16 , wherein the plurality of input optical fibers are fixed to the inner wall of the case with a light-transmitting resin. an optical combiner according to any one of claims 1 to 17 ;
a plurality of light sources for injecting light into each of the input optical fibers;
A laser device comprising: A method for manufacturing an optical combiner having an optical component in which one end of each of a plurality of input optical fibers is connected to an output optical fiber,
A fiber for determining a magnitude relation of NA of the two input optical fibers when light beams having the same incident angle are separately incident from the other ends of the two input optical fibers in the plurality of input optical fibers. a judgment process;
an arrangement step of arranging the optical component such that the side surfaces of the plurality of input optical fibers are enclosed in a tubular case;
with
In the arranging step, the input optical fiber having a smaller NA among the two input optical fibers determined in the fiber determining step is set as a first input optical fiber, and the input optical fiber having a larger NA is set as a first input optical fiber. is the second input optical fiber, part of the light propagating from the output optical fiber toward the input optical fiber leaks from the first input optical fiber and is reflected by the inner wall of the case. and the energy of the light re-entering the first input optical fiber is smaller than the energy of the light re-entering the second input optical fiber after the leaked light is reflected by the inner wall. A method for manufacturing an optical combiner, characterized by:

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