WO2021241545A1

WO2021241545A1 - Optical combiner and laser device

Info

Publication number: WO2021241545A1
Application number: PCT/JP2021/019723
Authority: WO
Inventors: 亮吉松本; 智之藤田; 裕山口; 拓矢小林; 究鈴木
Original assignee: 株式会社フジクラ
Priority date: 2020-05-26
Filing date: 2021-05-25
Publication date: 2021-12-02

Abstract

The present invention provides an optical combiner capable of reducing the NA of light propagating through a core located outside a light output part. An optical combiner (40) is provided with a light output part (130) to which light input parts (110, 120) respectively having cores (11, 21) are connected. The light output part (130) includes a center core (31) to which the core (11) of the light input part (110) is optically coupled, and a ring core (33) to which the core (21) of the light input part (120) is optically coupled. The ring core (33) has an outside diameter larger than the outside diameter of the center core (31). The light input part (120) includes an optical fiber (20) and a light adjustment member (50) that causes light emitted from an end of the core (21) of the optical fiber (20) to propagate such that the emission angle thereof becomes smaller.

Description

Optical combiner and laser device

The present invention relates to an optical combiner and a laser device, and particularly relates to an optical combiner that combines and outputs light propagating through a plurality of optical fibers.

In the field of laser machining, in order to improve machining performance such as machining speed and machining quality, it is important to change the beam profile of the laser beam irradiating the machining object according to the material and thickness of the machining object. .. In recent years, from this point of view, by forming a plurality of optical waveguides on the optical fiber on the output side and controlling the laser light introduced into each of these optical waveguides, a beam of laser light irradiated to the object to be processed is applied. Techniques have also been developed to transform the profile into the desired form.

For example, in Patent Document 1 and Patent Document 2, the central core of an output optical fiber is described as an optical combiner for introducing laser light into an output optical fiber having a central core as an optical waveguide and an outer core located around the central core. Correspondingly, one or more optical fibers (center side optical fibers) are arranged on the center side, and a plurality of optical fibers (outer optical fibers) are annularly arranged around the center side optical fiber corresponding to the outer core of the output optical fiber. The arrangement is disclosed (see FIGS. 8a and 8b of Patent Document 1 and FIG. 14 of Patent Document 2). With the diversification of laser processing in recent years, it is considered to realize a desired beam profile by variously changing the parameters of the laser beam introduced into a plurality of optical waveguides of the optical fiber on the output side. The NA of light can be considered as one of the parameters of such laser light.

Here, in the present specification, the NA of light propagating in the core of an optical fiber means a quantity defined by NA = nsinθ, where n is the refractive index of the core and θ is the propagation angle of the light. There is. When the light propagating in the core of the optical fiber is incident on a medium having a refractive index n'(for example, air), the NA of the light propagating in the core of the optical fiber can be determined by measuring the spread angle θ'of the light in the medium. It can be evaluated by NA = n'sinθ'(= nsinθ).

Japanese Unexamined Patent Publication No. 2009-145888 U.S. Pat. No. 9620925

The first object of the present invention is to provide an optical combiner capable of reducing the NA of light propagating in a core located outside the optical output unit.

A second object of the present invention is to provide a laser device capable of reducing the NA of the laser beam emitted from the outer core.

According to the first aspect of the present invention, there is provided an optical combiner capable of reducing the NA of light propagating through a core located outside the optical output unit. This optical combiner includes at least one first optical input unit having a first input optical waveguide, at least one second optical input unit having a second input optical waveguide, and the first optical input unit. And an optical output unit to which the second optical input unit is connected. The optical output unit includes a first core to which the first input optical waveguide of the at least one first optical input unit is optically coupled, and the first core of the at least one second optical input unit. Includes a second core to which the input optical waveguide of 2 is optically coupled. The first core has a first outer diameter, and the second core has a second outer diameter larger than the first outer diameter. The at least one second optical input unit is an optical fiber including a core as the second input optical waveguide and a cladding having a refractive index lower than the refractive index of the core and covering the periphery of the core. And an optical adjusting member that propagates the light emitted from the end of the core of the optical fiber so that the emission angle thereof becomes small.

According to the second aspect of the present invention, there is provided a laser device capable of emitting a low NA laser beam from an outer core. This laser apparatus includes at least one first laser light source that generates a laser beam, at least one second laser light source that generates a laser beam, and the above-mentioned optical combiner. The first input optical waveguide of the at least one first optical input unit of the optical combiner is optically coupled to the at least one first laser light source. The second input optical waveguide of the at least one second optical input section of the optical combiner is optically coupled to the at least one second laser light source.

FIG. 1 is a schematic block diagram showing a configuration of a laser device according to the first embodiment of the present invention. FIG. 2 is a diagram showing a cross section of the output optical fiber of the laser apparatus shown in FIG. 1 together with a refractive index distribution along the radial direction. FIG. 3 is a perspective view showing an optical combiner of the laser apparatus shown in FIG. FIG. 4 is an exploded perspective view of the optical combiner shown in FIG. FIG. 5 is a schematic block diagram showing a configuration of a laser device according to a second embodiment of the present invention. FIG. 6 is a perspective view showing an optical combiner of the laser apparatus shown in FIG. FIG. 7 is an exploded perspective view of the optical combiner shown in FIG.

Hereinafter, embodiments of the laser apparatus including the optical combiner according to the present invention will be described in detail with reference to FIGS. 1 to 7. In FIGS. 1 to 7, the same or corresponding components are designated by the same reference numerals, and duplicate description will be omitted. Further, in FIGS. 1 to 7, the scale and dimensions of each component may be exaggerated or some components may be omitted. In the following description, unless otherwise noted, terms such as "first" and "second" are only used to distinguish the components from each other and represent a particular order or order. It's not a thing.

FIG. 1 is a schematic block diagram showing the configuration of the laser device 1 according to the first embodiment of the present invention. As shown in FIG. 1, the laser apparatus 1 in the present embodiment generates a laser light source 2 (first laser light source) that generates a laser beam, an optical fiber 10 connected to the laser light source 2, and a laser beam. A plurality of laser light sources 3 (second laser light source), an optical fiber 20 connected to the laser light source 3, an output optical fiber 30 to which the

optical fibers

10 and 20 are connected, and a laser propagating through the

optical fibers

10 and 20. An optical combiner 40 that combines light and introduces it into the output optical fiber 30, a laser emitting unit 4 provided at the end of the output optical fiber 30, a control unit 5 that controls

laser light sources

2 and 3, and an object to be processed. It is equipped with a stage 6 that holds W. As the

laser light sources

2 and 3, for example, a fiber laser or a semiconductor laser can be used. In the following embodiments, unless otherwise specified, the direction from the

laser light sources

2 and 3 toward the laser emitting unit 4 is referred to as "downstream side", and the opposite direction is referred to as "upstream side". do.

FIG. 2 is a diagram showing a cross section of the output optical fiber 30 together with a refractive index distribution along the radial direction. As shown in FIG. 2, the output optical fiber 30 includes a center core 31 (first core), an inner clad 32 that covers the periphery of the center core 31, and a ring core 33 (second core) that covers the periphery of the inner clad 32. It has an outer clad 34 that covers the periphery of the ring core 33.

The refractive index of the inner clad 32 is lower than that of the center core 31 and the ring core 33, and the refractive index of the outer clad 34 is lower than that of the ring core 33. As a result, optical waveguides through which light propagates are formed inside the center core 31 and the ring core 33, respectively. As described above, in the present embodiment, the center core 31 and the ring core 33, which are independent optical waveguides, are concentrically arranged inside the output optical fiber 30. For example, the center core 31 and the ring core 33 are formed of quartz glass (SiO ₂ ), and a dopant having a property of lowering the refractive index (for example, fluorine (F) or boron (B)) is added to the quartz glass to form an inner clad 32. And the outer clad 34 may be formed. Alternatively, the inner clad 32 and the outer clad 34 are formed of quartz glass (SiO ₂ ), and a dopant having a property of increasing the refractive index (for example, germanium (Ge)) is added to form the center core 31 and the ring core 33. May be good. The periphery of the outer clad 34 is covered with, for example, a coating made of resin (reference numeral 35 in FIG. 3), but the coating is omitted in FIG.

The outer diameter of the center core 31 of the output optical fiber 30, the outer diameter of the inner clad 32, the outer diameter of the ring core 33, and the outer diameter of the outer clad 34 are important for determining the intensity distribution of the laser beam L emitted from the laser emitting portion 4. Although it is a factor, it can be appropriately set according to the application and output specifications of the laser device 1. As an example, the outer diameter of the center core 31 is 100 μm, the outer diameter of the inner clad 32 (inner diameter of the ring core 33) is 200 μm, the outer diameter of the ring core 33 is 300 μm, and the outer diameter of the outer clad 34 is 375 μm. Further, the refractive index of the inner clad 32 and the refractive index of the outer clad 34 may be the same or different.

FIG. 3 is a perspective view showing the optical combiner 40, and FIG. 4 is an exploded perspective view. As shown in FIGS. 3 and 4, the optical combiner 40 in the present embodiment includes an optical input unit 110 (first optical input unit) composed of a downstream end portion of an optical fiber 10 extending from a laser light source 2. A plurality of optical input units 120 (second optical input units) each composed of a downstream end portion of the optical fiber 20 extending from the laser light source 3 and an optical adjusting member 50, and an upstream end portion of the output optical fiber 30. The optical output unit 130 is included.

As shown in FIGS. 3 and 4, the optical fiber 10 constituting the optical input unit 110 has a core 11 and a clad 12 that covers the periphery of the core 11, and the refractive index of the clad 12 is the core. It is lower than the refractive index of 11. For example, the core 11 is formed of quartz glass (SiO ₂ ), and a dopant having the property of lowering the refractive index (for example, fluorine (F) or boron (B)) is added to the quartz glass to form the clad 12. May be good. Alternatively, the clad 12 may be formed of quartz glass (SiO ₂ ), and the core 11 may be formed by adding a dopant having the property of increasing the refractive index (for example, germanium (Ge)). As a result, an optical waveguide (first input optical waveguide) through which light propagates is formed inside the core 11 of the optical fiber 10. Therefore, the laser light generated by the laser light source 2 propagates inside the core 11 of the optical fiber 10. As an example, the outer diameter of the core 11 of the optical fiber 10 is 30 μm, and the outer diameter of the clad 12 is 125 μm. In the portion not shown in FIGS. 3 and 4, the periphery of the clad 12 of the optical fiber 10 is covered with, for example, a coating made of resin (not shown).

Further, the optical fiber 20 of the optical input unit 120 has a core 21 and a clad 22 that covers the periphery of the core 21, and the refractive index of the clad 22 is lower than that of the core 21. For example, the core 21 is formed of quartz glass (SiO ₂ ), and a dopant having the property of lowering the refractive index (for example, fluorine (F) or boron (B)) is added to the quartz glass to form the clad 22. May be good. Alternatively, the clad 22 may be formed of quartz glass (SiO ₂ ), and the core 21 may be formed by adding a dopant having the property of increasing the refractive index (for example, germanium (Ge)). As a result, an optical waveguide (second input optical waveguide) through which light propagates is formed inside the core 21 of the optical fiber 20. Therefore, the laser light generated by the laser light source 3 propagates inside the core 21 of the optical fiber 20. As an example, the outer diameter of the core 21 of the optical fiber 20 is 30 μm, and the outer diameter of the clad 22 is 125 μm. In the portion not shown in FIGS. 3 and 4, the periphery of the clad 22 of the optical fiber 20 is covered with, for example, a coating made of resin (not shown). Further, in the present embodiment, the optical fiber 10 and the optical fiber 20 are made of optical fibers having the same configuration and dimensions, but the optical fiber 10 and the optical fiber 20 may be made of different optical fibers. ..

Further, the light adjustment member 50 of the light input unit 120 is a cylindrical member having a function of reducing the emission angle of the laser light propagating inside. That is, the optical adjustment member 50 propagates the laser light emitted from the emission end portion 20A (see FIG. 4) of the optical fiber 20 of the optical input unit 120 so that the emission angle thereof becomes small, and the emission end portion 50A (FIG. 4). 4) is configured to emit light. As such an optical adjusting member 50, for example, a GRIN (Graded Index or Gradient Index) lens member whose refractive index gradually decreases from the central axis toward the outer side in the radial direction can be used. Such a GRIN lens member can be formed, for example, by adding a dopant such as germanium (Ge) to a central portion of a cylindrical glass made of quartz at a high concentration. As an example, the outer diameter of the light adjusting member 50 is 125 μm.

As shown in FIGS. 3 and 4, in the optical output unit 130, the upstream end portion of the coating 35 covering the periphery of the outer clad 34 of the output optical fiber 30 is removed, and the outer clad 34 is exposed to the outside. There is. The above-mentioned

optical input portions

110 and 120 are fused and connected to the upstream end surface (connection end surface) 135 of the portion where the outer clad 34 is exposed. Specifically, in the present embodiment, the size of the center core 31 of the optical output unit 130 is larger than that of the core 11 of the optical input unit 110, and in the optical input unit 110, the core 11 of the optical fiber 10 is optical. It is fused and connected to the optical output unit 130 so as to be located within the region of the center core 31 of the output unit 130. Further, the optical input unit 120 is fused and connected to the optical output unit 130 so that the emission end portion 50A of the optical adjustment member 50 of the optical input unit 120 is optically coupled to the ring core 33 of the optical output unit 130.

With such a configuration, the laser light generated by the laser light source 2 propagates inside the core 11 of the optical fiber 10, reaches the optical input unit 110 of the optical combiner 40, and is incident on the center core 31 of the optical output unit 130. do. The laser light incident on the center core 31 of the optical output unit 130 propagates inside the center core 31 of the output optical fiber 30 and is directed from the laser emitting unit 4 toward the processing object W on the stage 6 as a part of the laser light L. It is irradiated (see FIG. 1).

Further, the laser light generated by the laser light source 3 propagates inside the core 21 of the optical fiber 20 and reaches the optical input unit 120 of the optical combiner 40. The laser beam incident on the optical adjustment member 50 from the optical fiber 20 of the optical input unit 120 has a smaller emission angle while propagating through the optical adjustment member 50, and is emitted from the emission end 20A of the optical fiber 20. It is incident on the ring core 33 of the optical output unit 130 at a small emission angle. The laser light incident on the ring core 33 of the optical output unit 130 propagates inside the ring core 33 of the output optical fiber 30 and is directed from the laser emitting unit 4 toward the processing object W on the stage 6 as a part of the laser light L. It is irradiated (see FIG. 1).

As described above, in the laser apparatus 1 of the present embodiment, the laser beam L including the laser beam generated by the laser light source 2 on the center side and the laser beam generated by the laser light source 3 on the outside thereof is the laser emitting portion. It is irradiated from 4 toward the workpiece W on the stage 6.

Here, as shown in FIG. 1, the output optical fiber 30 between the optical combiner 40 and the laser emitting unit 4 has excess light leaked from the center core 31 or the ring core 33 of the output optical fiber 30 to the outer clad 34. A light removing unit 7 for removing the clad mode light) is provided. Since a known structure (clad mode stripper) can be used as the light removing unit 7, the details thereof will be omitted. Since the light removing unit 7 can remove unnecessary light leaked from the center core 31 or the ring core 33 of the output optical fiber 30 to the outer clad 34, such light is emitted from the laser emitting unit 4. It is possible to suppress adverse effects on L.

The control unit 5 can control these

laser light sources

2 and 3 by, for example, controlling the current supplied to the

laser light sources

2 and 3. By controlling the

laser light sources

2 and 3 by the control unit 5 in this way, the power of the laser light generated by the laser light source 2 and the power of the laser light generated by the laser light source 3 can be changed. Thereby, the power on the center side of the laser beam L output from the laser emitting unit 4 of the laser apparatus 1 and the power on the outer side thereof can be adjusted, and the profile of the laser beam L can be easily changed.

For example, when cutting a work object W which is a thin metal plate, a small-diameter circular beam having a high optical power density on the center side of the laser beam L is used to cut the work object W which is a thick metal plate. When cutting, use a large-diameter ring-shaped beam with a small rate of change in spot diameter and optical power density at a position deviated from the beam waist in the laser propagation direction (thickness direction of the workpiece W). Often. Such a large-diameter ring-shaped beam has an advantage that the optical power density at the beam waist portion can be increased as compared with a circular beam even if the beam diameter and the beam output are the same. Suitable for cutting. In processing using such a large-diameter ring-shaped beam, it is presumed that it is advantageous to use a low NA beam rather than a small-diameter circular beam.

As in the present embodiment, the laser beam is introduced into the ring core 33 of the output optical fiber 30 after reducing the emission angle of the laser light propagating through the core 21 of the optical fiber 20 by the optical adjustment member 50 of the optical input unit 120. The NA of the laser beam output from the ring core 33 of the emitting unit 4 can be reduced. Therefore, by using such a laser beam for processing the processing object W, it is possible to suppress fluctuations in the beam diameter and the optical power density on the front surface, the inside, and the back surface of the processing object W. As described above, according to the present embodiment, it is possible to irradiate the processing object W with a laser beam L suitable for processing, for example, a thick metal plate.

The configuration of the laser light source 2 and the configuration of the laser light source 3 may be the same, and even if the NA of the laser light generated by the laser light source 2 and the NA of the laser light generated by the laser light source 3 are the same. good. In this case, the laser light incident on the ring core 33 of the light output unit 130 from the light adjustment member 50 of the light input unit 120 is compared with the NA of the laser light incident on the center core 31 of the light output unit 130 from the light input unit 110. NA can be lowered.

Further, in the present embodiment, the laser light source 2 and the laser light source 3 are shown as separate light sources, but one light source is provided with two output ports, and the first output port is connected to the optical fiber 10. The second output port may be connected to the optical fiber 20. In this case, the above-mentioned laser light source 2 and laser light source 3 can be realized by switching between the first output port and the second output port by, for example, a spatial optical system switch. Alternatively, two output ports may be provided on both sides of one amplification optical fiber, the first output port may be connected to the optical fiber 10, and the second output port may be connected to the optical fiber 20. In this case, if two sets of fiber Bragg gratings having different reflected wavelength bands are arranged across the amplification optical fiber, the generated laser light can be directed to each output port by each set of fiber Bragg gratings. , The above-mentioned laser light source 2 and laser light source 3 can be realized.

In the present embodiment, each optical input unit 120 includes the optical adjustment member 50, but only a part of the optical input unit 120 may include the optical adjustment member 50. Further, the optical input unit 110 may include an optical adjusting member similar to the optical adjusting member 50.

FIG. 5 is a schematic block diagram showing the configuration of the laser device 401 according to the second embodiment of the present invention. As shown in FIG. 5, the laser device 401 in the present embodiment includes a plurality of laser light sources 3 that generate laser light, an optical fiber 20 connected to the laser light source 3, and a plurality of laser light sources 402 that generate laser light. The optical fiber 410 connected to the laser light source 402, the optical combiner 440 that combines the laser light propagating through the

optical fibers

20 and 410 and introduced into the output optical fiber 30, and the laser light source 402 (first laser light source). And a control unit 405 that controls the laser light source 3 (second laser light source). As the laser light source 402, for example, a fiber laser or a semiconductor laser can be used.

FIG. 6 is a perspective view showing the optical combiner 440, and FIG. 7 is an exploded perspective view. As shown in FIGS. 6 and 7, the optical combiner 440 in the present embodiment has an optical input unit 520 (first optical input unit) configured by the intermediate optical fiber 420 and an optical fiber 20 extending from the laser light source 3. A plurality of optical input units 120 (second optical input units) each composed of a downstream end portion and an optical adjusting member 50, and a plurality of each composed of a plurality of downstream end portions of an optical fiber 410 extending from a laser light source 402. Includes an optical input unit 510 (third optical input unit), a bridge fiber 450 connected to these optical input units 510, and an optical output unit 130 composed of an upstream end portion of the output optical fiber 30. I'm out. The intermediate optical fiber 420 is connected to the downstream side of the bridge fiber 450.

As shown in FIG. 7, the intermediate optical fiber 420 constituting the optical input unit 520 has a core 421 and a clad 422 that covers the periphery of the core 421, and the refractive index of the clad 422 is that of the core 421. It is lower than the refractive index. As a result, an optical waveguide (first input optical waveguide) through which light propagates is formed inside the core 421 of the intermediate optical fiber 420.

As described in the first embodiment, an optical waveguide (second input optical waveguide) through which light propagates is formed inside the core 21 of the optical fiber 20 constituting the optical input unit 120. The laser light generated by the laser light source 3 propagates through the core 21 of the optical fiber 20 and reaches the optical input unit 120 of the optical combiner 440. The emission angle of the laser beam incident on the optical adjustment member 50 from the optical fiber 20 of the optical input unit 120 becomes smaller while propagating through the optical adjustment member 50, and the laser light is emitted from the emission end portion 20A of the optical fiber 20. Also incident on the ring core 33 of the optical output unit 130 at a small emission angle.

As shown in FIGS. 6 and 7, the optical fiber 410 constituting the optical input unit 510 has a core 411 and a clad 412 that covers the periphery of the core 411, and the refractive index of the clad 412 is the core. It is lower than the refractive index of 411. For example, the core 411 is formed of quartz glass (SiO ₂ ), and a dopant having the property of lowering the refractive index (for example, fluorine (F) or boron (B)) is added to the quartz glass to form a clad 412. May be good. Alternatively, the clad 412 may be formed of quartz glass (SiO ₂ ), and the core 411 may be formed by adding a dopant having a property of increasing the refractive index (for example, germanium (Ge)). As a result, an optical waveguide (third input optical waveguide) through which light propagates is formed inside the core 411 of the optical fiber 410. Therefore, the laser light generated by the laser light source 402 propagates through the core 411 of the optical fiber 410 and reaches the optical input unit 510 of the optical combiner 440. As an example, the outer diameter of the core 411 of the optical fiber 410 is 30 μm, and the outer diameter of the clad 412 is 125 μm. In the portion not shown in FIGS. 6 and 7, the periphery of the clad 412 of the optical fiber 410 is covered with, for example, a coating made of resin (not shown). Further, in the present embodiment, the optical fiber 410 and the optical fiber 20 are made of optical fibers having the same configuration and dimensions, but the optical fiber 410 and the optical fiber 20 may be made of different optical fibers. ..

The bridge fiber 450 has a core 451 and a clad 452 that covers the periphery of the core 451. The refractive index of the clad 452 is lower than that of the core 451, and an optical waveguide through which light propagates is formed inside the core 451. The bridge fiber 450 having such a core-clad structure inside has a first cylindrical portion 461 extending with a constant outer diameter along the optical axis, and a first cylindrical portion 461 gradually having an outer diameter along the optical axis. It includes a reduced diameter portion 462 in which the diameter is reduced, and a second cylindrical portion 463 extending from the reduced diameter portion 462 with a constant outer diameter along the optical axis direction.

The end surface of the first cylindrical portion 461 is a bridge incident surface 465 to which the downstream end portions of the respective optical input portions 510 are fused and connected. In the present embodiment, the three optical input units 510 are connected to the bridge incident surface 465 of the bridge fiber 450 in a state of being in contact with each other. The size of the core 451 on the bridge entrance surface 465 of the bridge fiber 450 is such that the core 411 of all the optical input units 510 can be contained therein, and the optical input unit 510 and the bridge fiber 450 are 3 All the cores 411 of the optical input unit 510 are fused and connected so as to be located in the region of the core 451 on the bridge entrance surface 465 of the bridge fiber 450.

As described above, the bridge fiber 450 is configured to propagate the laser light emitted from the core 411 of the optical input unit 510 into the core 451 and reduce the beam diameter by the reduced diameter portion 462. At this time, the laser beam is repeatedly reflected on the inner peripheral surface of the clad 452 of the reduced diameter portion 462 to increase the divergence angle (angle in the direction in which the light spreads with respect to the optical axis of the core 451), and the laser emitted from the bridge fiber 450. The light emission angle increases. As described above, the bridge fiber 450 in the present embodiment is a member that increases the emission angle of the propagating laser beam. In order to suppress the reflection when the laser beam is incident on the core 451 of the bridge fiber 450 from the core 411 of the optical input unit 510, the refractive index of the core 451 of the bridge fiber 450 is the refraction index of the core 411 of the optical input unit 510. It is preferable that it is substantially the same as the rate.

The end surface of the second cylindrical portion 463 located on the side opposite to the bridge entrance surface 465 in the optical axis direction is the bridge exit surface 466 to which the intermediate optical fiber 420 is fused and connected. Here, the size of the core 421 of the intermediate optical fiber 420 is larger than the size of the core 451 on the bridge exit surface 466 of the bridge fiber 450, and the bridge fiber 450 and the optical input unit 520 (intermediate optical fiber 420) Is fused and connected so that the core 451 of the bridge fiber 450 on the bridge exit surface 466 is located within the region of the core 421 of the intermediate optical fiber 420.

As described above, the intermediate optical fiber 420 of the optical input unit 520 is configured to propagate the laser light propagating through the core 451 of the bridge fiber 450 to the inside of the core 421. In order to suppress reflection when laser light is incident on the core 421 of the intermediate optical fiber 420 from the core 451 of the bridge fiber 450, the refractive index of the core 421 of the intermediate optical fiber 420 is the refraction of the core 451 of the bridge fiber 450. It is preferable that it is substantially the same as the rate.

The bridge fiber 450 in the present embodiment has a clad 452 on the outside of the core 451 as a low refractive index medium having a refractive index lower than that of the core 451. Such a low refractive index medium is clad. It is not limited to the coating layer such as 452, and for example, an air layer may be formed around the core 451 and this air layer may be used as a low refractive index medium.

The connection end surface 135 of the optical output unit 130 has a downstream end portion (emission end portion 50A) of the optical input unit 120 (optical adjustment member 50) and a downstream end portion of the optical input unit 520 (intermediate optical fiber 420). Each is fused and connected. At the downstream end (connection end) of the optical input unit 120 and the optical input unit 520, six optical input units 120 are located outside the optical input unit 520 (intermediate optical fiber 420) from the center of the intermediate optical fiber 420, etc. They are arranged at a distance, and the adjacent

optical input units

120 and 520 are in close contact with each other. Here, the connection ends of the

optical input units

120 and 520 of the optical output unit 130 are arranged so that the center of the intermediate optical fiber 420 arranged in the center _{coincides with the center O 1} (see FIG. 2) of the output optical fiber 30. It is fused and connected to the connection end surface 135.

The area of the center core 31 of the optical output unit 130 is large enough to include the core 421 of the optical input unit 520 arranged in the center. The optical input unit 520 is fused and connected to the optical output unit 130 so that the core 421 of the intermediate optical fiber 420 of the optical input unit 520 is located in the region of the center core 31 of the optical output unit 130. Further, the optical input unit 120 is fused and connected to the optical output unit 130 so that the optical adjustment member 50 of the optical input unit 120 is optically coupled to the ring core 33 of the optical output unit 130.

With such a configuration, the laser light generated by the laser light source 402 propagates inside the core 411 of the optical fiber 410 and is incident on the core 451 of the bridge fiber 450 from the bridge incident surface 465 of the bridge fiber 450. The laser beam incident on the core 451 of the bridge fiber 450 propagates through the core 451 of the bridge fiber 450 while being reflected at the interface between the core 451 and the clad 452. NA) becomes large. The laser beam in a state where the beam diameter is small and the emission angle is large enters the core 421 of the intermediate optical fiber 420 from the bridge emission surface 466 of the bridge fiber 450, propagates inside the core 421, and propagates inside the core 421 of the optical output unit 130. It is incident on the center core 31. The laser light incident on the center core 31 of the optical output unit 130 propagates inside the center core 31 and is emitted from the laser emitting unit 4 toward the processing object W on the stage 6 as a part of the laser light L (FIG. 5).

Further, the laser light generated by the laser light source 3 propagates inside the core 21 of the optical fiber 20 and reaches the optical input unit 120 of the optical combiner 40. The laser beam incident on the optical adjustment member 50 from the optical fiber 20 of the optical input unit 120 has a smaller emission angle while propagating through the optical adjustment member 50, and is emitted from the emission end 20A of the optical fiber 20. It is incident on the ring core 33 of the light output unit 130 from the emission end portion 50A at a small emission angle. The laser light incident on the ring core 33 of the optical output unit 130 propagates inside the ring core 33 and is emitted from the laser emitting unit 4 toward the processing object W on the stage 6 as a part of the laser light L (FIG. 5).

As described above, in the present embodiment, the laser light from the plurality of laser light sources 402 can be coupled by the bridge fiber 450 and introduced into the center core 31 of the optical output unit 130, so that the center core 31 of the output optical fiber 30 is propagated. The power of the laser beam can be easily increased.

The control unit 405 can control these

laser light sources

3, 402, for example, by controlling the current supplied to the

laser light sources

3, 402. By controlling the

laser light sources

3 and 402 by the control unit 405 in this way, the power of the laser light generated by the laser light source 3 and the power of the laser light generated by the laser light source 402 can be changed. As a result, the power on the center side of the laser beam L output from the laser emitting unit 4 of the laser apparatus 401 and the power on the outside thereof can be adjusted, and the profile of the laser beam L can be easily changed.

As described above, also in this embodiment, the emission angle of the laser beam propagating through the core 21 of the optical fiber 20 is reduced by the optical adjusting member 50 of the optical input unit 120, and then introduced into the ring core 33 of the optical output unit 130. Can be done. Therefore, it is possible to reduce the NA of the laser beam output from the ring core 33 of the laser emitting unit 4, and it is possible to irradiate the machined object W with the laser beam L suitable for processing a thick metal plate, for example. Is.

The configuration of the laser light source 3 and the configuration of the laser light source 402 may be the same, and even if the NA of the laser light generated by the laser light source 3 and the NA of the laser light generated by the laser light source 402 are the same. good. In the present embodiment, the NA of the laser light generated by the laser light source 402 increases while propagating through the reduced diameter portion 462 of the bridge fiber 450, so that the NA of the laser light propagating through the core 421 of the optical input section 520 is Although it is higher than the NA of the laser light propagating through the core 21 of the optical fiber 20 of the optical input unit 120, the laser light incident on the ring core 33 of the optical output unit 130 from the optical input unit 120 by the above-mentioned optical adjustment member 50. The NA can be adjusted to be even lower than the NA of the laser beam incident on the center core 31 of the optical output unit 130 from the optical input unit 520.

Further, in the present embodiment, the laser light source 3 and the laser light source 402 are shown as separate light sources, but as described above, one light source is provided with two output ports, and a spatial optical system switch or two sets of fibers are provided. The above-mentioned laser light source 3 and laser light source 402 can also be realized by switching the output port using the Bragg grating.

The output optical fiber 30 (optical output unit 130) in the above-described embodiment has two optical waveguides including a center core 31 and a ring core 33, but the output optical fiber 30 has three or more optical waveguides. You may be doing it. Further, the cross-sectional shape of the core (optical waveguide) included in the output optical fiber 30 is not limited to the circular shape or the annular shape as shown in the figure.

Further, although the output optical fiber 30 (optical output unit 130) in the above-described embodiment has two

clads

32 and 34, the output optical fiber 30 may have a single clad layer. , Or may have three or more clad layers. For example, as the output optical fiber 30 having a single clad layer, the refractive index such that the ring core 33 corresponds to the first clad of the center core 31 without the inner clad 32 of the output optical fiber 30 in the above-described embodiment exists. Those having a profile are conceivable. Further, as a low refractive index medium having a refractive index lower than that of the ring core 33, an outer clad 34 is formed around the ring core 33, and such a low refractive index medium is like the outer clad 34. The present invention is not limited to the coating layer, and for example, an air layer may be formed around the ring core 33, and this air layer may be used as a low refractive index medium.

In the above-described embodiment, the configuration of the laser light source 2, the configuration of the laser light source 3, and the configuration of the laser light source 402 may be the same or different. Further, the wavelength of the laser light generated by the laser light source 2, the wavelength of the laser light generated by the laser light source 3, and the wavelength of the laser light generated by the laser light source 402 may be the same or different. May be good.

Although the preferred embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment and may be implemented in various different forms within the scope of the technical idea.

As described above, according to the first aspect of the present invention, there is provided an optical combiner capable of reducing the NA of light propagating through a core located outside the optical output unit. This optical combiner includes at least one first optical input unit having a first input optical waveguide, at least one second optical input unit having a second input optical waveguide, and the first optical input unit. And an optical output unit to which the second optical input unit is connected. The optical output unit includes a first core to which the first input optical waveguide of the at least one first optical input unit is optically coupled, and the first core of the at least one second optical input unit. Includes a second core to which the input optical waveguide of 2 is optically coupled. The first core has a first outer diameter, and the second core has a second outer diameter larger than the first outer diameter. The at least one second optical input unit is an optical fiber including a core as the second input optical waveguide and a cladding having a refractive index lower than the refractive index of the core and covering the periphery of the core. And an optical adjusting member that propagates the light emitted from the end of the core of the optical fiber so that the emission angle thereof becomes small. As the light adjusting member, a GRIN lens whose refractive index gradually decreases from the central axis toward the outer side in the radial direction can be used.

According to such a configuration, the light incident on the optical adjustment member from the core of the optical fiber of the second optical input unit has a small emission angle while propagating through the optical adjustment member, and the light is emitted from the end of the optical fiber. Since the light is incident on the second core of the optical output unit at a smaller emission angle than when it is emitted, the NA of the light propagating through the second core of the optical output unit can be reduced.

The optical output unit is a center core as the first core, and has a center core arranged in the center and an inner clad having a refractive index lower than the refractive index of the center core and covering the periphery of the center core. The ring core as the second core may be included. The ring core has a refractive index higher than that of the inner clad and covers the periphery of the inner clad.

The optical combiner may further include a plurality of third optical input units each having a third input optical waveguide, and a bridge fiber. The diameter of the bridge fiber gradually increases as the distance from the bridge incident surface to which the third input optical waveguide of the plurality of third optical input units is optically coupled and the bridge incident surface along the optical axis direction gradually increases. It has a reduced diameter portion that becomes smaller and a bridge exit surface that is opposite to the bridge entrance surface in the optical axis direction. The at least one first optical input unit includes an intermediate optical fiber including a core optically coupled to the bridge exit surface of the bridge fiber. According to such a configuration, light from a plurality of third optical input units can be coupled by a bridge fiber and introduced into the first core of the optical output unit, so that the first core of the optical output unit can be introduced. The power of light propagating can be easily increased.

According to such an embodiment, as described above, the NA of the laser beam incident on the second core of the optical output unit of the optical combiner can be reduced, so that the low NA laser beam is emitted from the outer core. It is possible to emit light.

The laser device may further include a light removing unit that removes light leaking from the first core or the second core of the optical output unit of the optical combiner. With such a light removing unit, it is possible to remove unnecessary light leaking from the first core or the second core of the light output unit of the optical combiner.

The laser device is controlled by the at least one first laser light source and the at least one second laser light source, thereby using the at least one first laser light source and the at least one second laser light source. Further, a control unit for adjusting the output of the generated laser beam may be provided. With such a control unit, the power of the laser beam output from the laser apparatus can be adjusted, and the profile of the laser beam can be easily changed.

As described above, according to the first aspect of the present invention, there is provided an optical combiner capable of reducing the NA of light propagating through a core located outside the optical output unit. This optical combiner includes at least one first optical input unit having a first input optical waveguide, at least one second optical input unit having a second input optical waveguide, and the first optical input unit. And an optical output unit to which the second optical input unit is connected. The optical output unit includes a first core to which the first input optical waveguide of the at least one first optical input unit is optically coupled, and the first core of the at least one second optical input unit. Includes a second core to which the input optical waveguide of 2 is optically coupled. The first core has a first outer diameter, and the second core has a second outer diameter larger than the first outer diameter. The at least one second optical input unit is an optical fiber including a core as the second input optical waveguide and a cladding having a refractive index lower than the refractive index of the core and covering the periphery of the core. And an optical adjusting member that propagates the light emitted from the end of the core of the optical fiber so that the emission angle thereof becomes small.

This application is based on Japanese Patent Application No. 2020-091461 filed on May 26, 2020, and claims the priority of the application. The disclosure of such application is incorporated herein by reference in its entirety.

The present invention is suitably used for an optical combiner that combines and outputs light propagating through a plurality of optical fibers.

1 Laser device 2 (1st) laser light source 3 (2nd) laser light source 4 Laser emission unit 5 Control unit 6 Stage 7

Light removal unit

10, 20 Optical fiber 30 Output optical fiber 31 Center core (1st core)
32 Inner clad 33 Ring core (second core)
34 Outer clad 40,440 Optical combiner 50 Optical adjuster 110 (1st) Optical input unit 120 (2nd) Optical input unit 130 Optical output unit 135 Connection end face 401 Laser device 402 (1st) Laser light source 405 Control Section 410 Optical fiber 420 Intermediate optical fiber 450 Bridge fiber 461 First cylindrical section 462 Reduced diameter section 465 Second cylindrical section 465 Bridge entrance surface 466 Bridge exit surface 510 (third) Optical input section 520 (first) Optical input section

Claims

With at least one first optical input unit having a first input optical waveguide,
With at least one second optical input unit having a second input optical waveguide,
An optical output unit to which the first optical input unit and the second optical input unit are connected.
A first core to which the first input optical waveguide of the at least one first optical input unit is optically coupled, the first core having a first outer diameter, and the like.
A second core to which the second input optical waveguide of the at least one second optical input unit is optically coupled and having a second outer diameter larger than the first outer diameter. Equipped with an optical output unit including 2 cores
The at least one second optical input unit is
An optical fiber comprising a core as the second input optical waveguide and a cladding having a refractive index lower than that of the core and covering the periphery of the core.
A light adjusting member for propagating light emitted from an end portion of the core of the optical fiber so that the emission angle thereof is reduced.
Optical combiner.
The optical combiner according to claim 1, wherein the optical adjusting member is composed of a GRIN lens whose refractive index gradually decreases from the central axis toward the outer side in the radial direction.
The optical output unit is
A center core as the first core, the center core arranged in the center, and the center core.
With an inner clad that has a refractive index lower than that of the center core and covers the periphery of the center core,
The optical combiner according to claim 1 or 2, wherein the ring core as the second core has a refractive index higher than that of the inner clad and includes a ring core that covers the periphery of the inner clad.
A plurality of third optical input units each having a third input optical waveguide,
A bridge incident surface to which the third input optical waveguide of the plurality of third optical input units is optically coupled, and a reduced diameter portion whose diameter gradually decreases as the distance from the bridge incident surface along the optical axis direction increases. And a bridge fiber having a bridge exit surface on the opposite side of the bridge entrance surface in the optical axis direction.
The at least one first optical input unit includes an intermediate optical fiber including a core optically coupled to the bridge exit surface of the bridge fiber.
The optical combiner according to any one of claims 1 to 3.
With at least one first laser source that produces laser light,
With at least one second laser source that produces a laser beam,
The optical combiner according to any one of claims 1 to 4 is provided.
The first input optical waveguide of the at least one first optical input section of the optical combiner is optically coupled to the at least one first laser light source.
The second input optical waveguide of the at least one second optical input section of the optical combiner is optically coupled to the at least one second laser light source.
Laser device.
The laser device according to claim 5, further comprising an optical removing unit for removing light leaking from the first core or the second core of the optical output unit of the optical combiner.
By controlling the at least one first laser light source and the at least one second laser light source, the laser light generated by the at least one first laser light source and the at least one second laser light source. The laser apparatus according to claim 5 or 6, further comprising a control unit for adjusting the output of the above.