JP2017156633A - Laser system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser system which can be miniaturized, prevents property deterioration, and efficiently provides large output.SOLUTION: A laser system comprises: a plurality of light source units 11-17, each having a plurality of lasers and being configured to output a primary laser beam obtained by optically coupling outputs of the plurality of lasers; an optical coupler 3 configured to optically couple the primary laser beams to output a secondary laser beam; and a hollow core fiber 4 for transmitting the secondary laser beam output by the optical coupler 3, where a hollow core of the hollow core fiber 4 is covered by an output end of the optical coupler 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser system for high output in which a plurality of laser beams are optically coupled.

  Conventionally, as a laser beam irradiation device used in medical equipment and machining, a plurality of laser beams are optically coupled using a bundle fiber, and the combined laser beam is transmitted using a delivery fiber (light guide). A laser system that outputs the signal is known (see Patent Document 1).

  In the laser system as described in Patent Document 1, in recent years, a high-power laser system in which a plurality of coupled light sources such as a direct diode laser (DDL) and a multimode (MM) fiber laser are further bundled has been studied. ing. However, in such a high-power laser system, it is necessary to increase the output numerical aperture (NA) of the delivery fiber or increase the optical fiber diameter.

  A glass-based fiber is usually used as the delivery fiber. However, since the numerical aperture of the glass fiber is controlled by the refractive index of the dopant, there is a limit to increasing the numerical aperture. Further, when the fiber diameter of the delivery fiber is increased, it is difficult to bend, and there may be a problem in handling. Thus, it has been difficult to realize a laser system that efficiently obtains a large output without degrading characteristics.

Japanese Patent Laid-Open No. 7-027950

  An object of the present invention is to provide a laser system that can be miniaturized, can prevent deterioration of characteristics, and can efficiently obtain a large output.

  In one embodiment of the present invention, (a) a plurality of light source units each having a plurality of lasers and outputting primary laser beams obtained by optically combining the outputs of the plurality of lasers, and (b) a primary laser beam. Are coupled optically to output secondary laser light, and (c) a hole core fiber that transmits the secondary laser light output by the optical coupler is provided. The gist of the present invention is that the laser system is such that, at the end, the exit core of the optical coupler covers the hole core of the hole core fiber.

In one embodiment of the present invention, the number of lasers is n1, the numerical aperture is NA1, the diameter of the lasers that transmits light is D1, the number of light source units is n2, the numerical aperture is NA2, and the light source unit is primary. The diameter for transmitting the laser beam is D2, the numerical aperture of the optical coupler and hole core fiber is NA3, and the diameter of the optical coupler and hole core fiber transmitting the secondary laser beam is D3,

n1 (NA1 × D1) <n2 (NA2 × D2) <NA3 × D3

The main point is to satisfy this relationship.

  In one aspect of the present invention, the gist is that the diameter of the emission end is equal to or larger than the diameter of the hole core.

  In one aspect of the present invention, the hole core fiber has a hole portion extending in the longitudinal direction of the hole core on the outer periphery of the hole core, and the cross-sectional area of the emission end is a size that further blocks the hole portion. It is a summary.

  In one aspect of the present invention, the gist is that the refractive index of the central portion of the emission end is higher than the refractive index of the peripheral portion surrounding the central portion.

  In one aspect of the present invention, the gist further includes a coating layer covering the outer periphery of the exit end and the entrance end of the hole core fiber.

  In one aspect of the present invention, the gist is that the outer periphery of the emitting end is inserted on the incident end side of the hole core so as to be in contact with the inner wall of the hole core.

  Another aspect of the present invention is that the primary laser light is output light of a direct diode laser.

  In one aspect of the present invention, each of the numerical aperture of the optical coupler and the numerical aperture of the hole core fiber is 0.3 or more.

  Another aspect of the present invention is to further include an optically transparent end cap that closes the output end of the hole core fiber.

  In one aspect of the present invention, the gist is that a fused portion is provided between the exit end and the entrance end of the hole core fiber.

  ADVANTAGE OF THE INVENTION According to this invention, the laser system which can be reduced in size, can prevent characteristic deterioration, and can obtain a high output efficiently can be provided.

It is the schematic which shows an example of the laser system which concerns on embodiment of this invention. It is the schematic which shows an example of the light source unit which concerns on embodiment of this invention. It is sectional drawing perpendicular | vertical to a longitudinal direction which shows an example of the optical fiber connected to the light source unit which concerns on embodiment of this invention. It is sectional drawing perpendicular | vertical to a longitudinal direction which shows an example of the optical coupler which concerns on embodiment of this invention. It is sectional drawing perpendicular | vertical to a longitudinal direction which shows an example of the hole core fiber which concerns on embodiment of this invention. FIG. 4 is a cross-sectional view taken along the light transmission direction showing an example of a connecting portion between the optical coupler and the hole core fiber according to the embodiment of the present invention (viewed from the IV-IV direction in FIG. 4 and the VV direction in FIG. 5); Is a sectional view). It is sectional drawing cut in the transmission direction of light which shows an example of the connection part of the optical coupler and hole core fiber which concern on the 1st modification of embodiment of this invention. It is sectional drawing cut in the transmission direction of light which shows an example of the connection part of the optical coupler and hole core fiber which concern on the 2nd modification of embodiment of this invention. It is sectional drawing cut in the transmission direction of the light which shows an example of the connection part of the optical coupler and hole core fiber which concern on the 3rd modification of embodiment of this invention. It is sectional drawing cut in the transmission direction of light which shows an example of the connection part of the optical coupler and hole core fiber which concern on the 4th modification of embodiment of this invention.

  Hereinafter, embodiments of the present invention and first to fourth modifications will be described with reference to the drawings. In the description of the drawings referred to in the following description, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the following embodiments and first to fourth modifications exemplify a laser system for embodying the technical idea of the present invention, and the technical idea of the present invention is configured as follows. The material of the parts, their shape, structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

  As shown in FIG. 1, the laser system according to the embodiment of the present invention includes a plurality of (seven in the example of FIG. 1) light source units 11 to 17, and a plurality of light source units 11 to 17 and optical fibers 21 to 27. And a hole core fiber 4 connected to the optical coupler 3.

  The light source units 11 to 17 each output a primary laser beam obtained by optically combining a plurality of laser beams. For example, as shown in FIG. 2, the light source unit 11 includes a plurality of (six in the example of FIG. 2) laser diodes (LD) 111 to 126 and a plurality of laser diodes 111 to 126 arranged corresponding to the plurality of laser diodes 111 to 126. The diffraction gratings 121 to 126 are provided and have a structure equivalent to or similar to the DDL (hereinafter, in this specification, the configuration of the light source units 11 to 17 as shown in FIG. These will be referred to as “DDL1 to DDL7”).

  The laser beams output from the plurality of laser diodes 111 to 126 are diffracted by the plurality of diffraction gratings 121 to 126 and combined to constitute DDL1. The output from the DDL 1 is input to the optical fiber 21 as primary laser light. The other light source units 12 to 17 shown in FIG. 1 can also be configured in the same manner as the light source unit 11 to obtain outputs from DDL2 to DDL7.

  In addition, you may comprise the light source units 11-17 using a some fiber laser. When a plurality of fiber lasers are used, for example, a plurality of single mode (SM) laser beams are combined to generate a multimode (MM) fiber laser beam, and the generated MM fiber laser beam is used as a primary laser beam. It may be output.

  As shown in FIG. 1, the plurality of primary laser beams output from the plurality of light source units 11 to 17 are respectively incident on the plurality of optical fibers 21 to 27. For example, as shown in FIG. 3, the optical fiber 21 includes a core 21a and a cladding 21b that covers the outer periphery of the core 21a and extends in the longitudinal direction of the core 21a and has a lower refractive index than the core 21a. . The other optical fibers 22 to 27 illustrated in FIG. 1 can be configured in the same manner as the optical fiber 21.

  The optical coupler 3 shown in FIG. 1 optically couples a plurality of primary laser beams output from the plurality of light source units 11 to 17 and outputs a secondary laser beam. For example, as shown in FIG. 4, the optical coupler 3 can be constituted by a fiber bundle bundled by inserting the emission end sides of the optical fibers 21 to 27 into a cylindrical ferrule 31. The ferrule 31 can be made of, for example, a glass tube or a resin. The optical coupler 3 is not limited to the configuration shown in FIG. 4 and may be any configuration as long as the light from the plurality of light source units 11 to 17 can be optically coupled without being spatially coupled.

  The hole core fiber 4 shown in FIG. 1 transmits and outputs the secondary laser light output from the optical coupler 3. The exit end side of the hole core fiber 4 is connected to, for example, a processing head of a laser processing machine, and a large output optically coupled can be used for laser processing. The hole core fiber 4 functions as a delivery fiber (transmission fiber).

  As shown in FIG. 5, the hole core fiber 4 has a hole core 41 provided at the center of an optical fiber made of quartz glass or the like, and a concentric structure in the longitudinal direction of the hole core 41 on the outer periphery of the hole core 41. The photonic crystal fiber has a plurality of (three layers) hole portions 42a, 42b, and 42c provided so as to extend. The hole portions 42 a, 42 b, and 42 c arranged concentrically and periodically form a clad that satisfies the Bragg reflection condition for confining light transmitted through the hole core 41.

  5 illustrates a Bragg clad in which three layers of hole portions 42a, 42b, and 42c are periodically provided along the radial direction on the outer periphery of the hole core 41. The structure is not limited to the structure shown in FIG. Since the hole core fiber 4 used in the laser system according to the embodiment of the present invention has at least the hole core 41, various structures and topologies can be adopted as the structure of the cladding and the like.

Here, the number of the plurality of lasers constituting the light source units 11 to 17 is n1, the numerical aperture is NA1, the diameter at which the plurality of lasers transmit light is D1, the number of the light source units 11 to 17 is n2, and the numerical aperture. Is NA2, the diameter of the light source units 11 to 17 transmitting the primary laser light is D2, the numerical aperture of the optical coupler 3 and the hollow core fiber 4 is NA3, and the optical coupler 3 and the hollow core fiber 4 are secondary. It is preferable to satisfy the relationship of the formula (1), where D3 is a diameter for transmitting the laser beam.

n1 (NA1 × D1) <n2 (NA2 × D2) <NA3 × D3 (1)

  By satisfying the relationship of Expression (1), it is possible to prevent leakage of light to the outside of the system. In the laser system according to the embodiment of the present invention, by using the hole core fiber 4 having the hole core 41 as the delivery fiber, a high numerical aperture NA3 can be realized. Can be satisfied. Therefore, the expansion of the diameter D3 in which the optical coupler 3 and the hole core fiber 4 transmit the secondary laser light can be suppressed.

  Here, in the laser system according to the embodiment of the present invention, as shown in FIG. 6, the emission end of the optical coupler 3 closes at least the entrance end of the hole core 41. The diameter D0 of the exit end of the optical coupler 3 is set to be larger than the diameter D3 of the hole core 41 and not more than the diameter D4 of the outermost hole part 42c. For example, the end of the ferrule 31 that is the outer peripheral portion of the optical coupler 3 and the incident end of the hole core fiber 4 are heat-sealed, for example, and the end of the ferrule 31 and the incident end of the hole core fiber 4 are A fusion part 3a is provided between them. 6 illustrates the case where the end portion of the ferrule 31 that is the outer peripheral portion of the output end of the optical coupler 3 blocks the hole 42a, the diameter D0 of the output end of the optical coupler 3 is illustrated. The emission end of the optical coupler 3 including the ferrule 31 may block only the incident end of the hole core 41.

  The outer periphery of the hole core fiber 4 is covered with a coating layer 43 made of stainless steel, resin, or the like. A connection flange 51 is provided on the output end side of the optical coupler 3, and a connection flange 52 is provided on the incident end side of the hole core fiber 4. The connection flanges 51 and 52 are coupled by a clamp 53. The optical coupler 3 and the hole core fiber 4 are aligned and fixed by the connecting flanges 51 and 52 and the clamp 53, and are connected to each other.

  6 illustrates a case where the cross section on the light emitting end side of the optical coupler 3 cut in the light transmission direction is rectangular, the cross-sectional structure gradually increases toward the light emitting end of the optical coupler 3. It may be a trapezoid (tapered shape) or the like that becomes thinner. Even in the case of the taper shape, the diameter D0 of the emission end face of the optical coupler 3 may be set larger than the diameter D3 of the hole core 41. In other words, the cross-sectional area of the output end of the optical coupler 3 only needs to be large enough to block the hole core 41.

  As described above, according to the laser system according to the embodiment of the present invention, by using the hole core fiber 4 having high non-linear resistance as the delivery fiber, the laser light is optically coupled in two stages, High output can be achieved efficiently.

  Further, as illustrated in FIG. 1, when the light source units 11 to 17 are DDL1 to DDL7, there is a possibility that it is preferable to the MM type fiber laser in terms of power consumption and the like. For this purpose, an optical fiber having a large diameter is required.

  On the other hand, since the hole core fiber 4 can realize a higher numerical aperture than the glass fiber, the numerical aperture NA3 of the optical coupler 3 and the hole core fiber 4 can be increased to 0.3 or more. it can. Therefore, even if the diameter D3 of the optical coupler 3 and the hole core fiber 4 is not made very large, the equation (1) can be satisfied, and many lasers such as 7 or 19 DDL couplings can be obtained. It becomes possible to combine.

  Furthermore, using a bundle fiber or the like as the optical coupler 3 makes it easy to satisfy the formula (1), so that leakage of light to the outside can be prevented and excellent in high output including safety. A system can be realized.

  Further, when the hole core fiber 4 is used as a delivery fiber, the hole core fiber is such that when impurities such as moisture and dirt enter the hole core 41, the hole core fiber 4 is deteriorated in characteristics over time. A unique problem due to the hole core 41 unique to 4 occurs.

  Therefore, in the laser system according to the embodiment of the present invention, the diameter D0 of the emission end of the optical coupler 3 is set slightly larger than the diameter D3 of the hole core 41 as shown in FIG. Thereby, the light emitted from the cores of the optical fibers 21 to 27 constituting the optical coupler 3 is incident on the incident end of the hole core 41, and the light emission end of the optical coupler 3 is the hole core 41. The incident end is blocked. Due to the structure in which the incident end is closed, impurities such as moisture and dirt can be prevented from entering the hole core 41, and the splicing of the hole core fiber 4 caused by the impurities entering the hole core 41 can be prevented. Suppressing temporal characteristic deterioration and ensuring reliable operation.

  Furthermore, as shown in FIG. 6, when the hole core fiber constituting the hole core fiber 4 has hole portions 42 a, 42 b, and 42 c in the outer cladding of the hole core 41, the hole portion Although the light transmitted through 42a, 42b, and 42c is less than the light transmitted through the hole core 41, if impurities such as moisture enter the hole portions 42a, 42b, and 42c, the hole core fiber 4 Reliability decreases.

  Regarding the problem on the clad side, according to the laser system according to the embodiment of the present invention, the connection flange 51 is provided on the emission end side of the optical coupler 3 and the connection provided on the incident end side of the hole core fiber 4 is provided. Since the connection with the flange 52 is made, the outer peripheral portion of the emission end of the optical coupler 3 and the connection flange 51 block the incident ends of the hole portions 42a, 42b, and 42c. For this reason, the connection flange 51 can prevent moisture and impurities from entering the hole portions 42a, 42b, and 42c constituting the cladding, and can further improve the reliability of the hole core fiber 4. The diameter D0 of the exit end of the optical coupler 3 is further reduced so that the optical coupler 3 closes only the hole core 41 and the connection flange 51 closes all the incident ends of the hole portions 42a, 42b, and 42c. It may be configured.

  Further, since the output end of the optical coupler 3 and the incident end of the hole core fiber 4 are connected using the connection flanges 51 and 52 and the clamp 53, the output end of the optical coupler 3 and the incident end of the hole core fiber 4 are connected. And mechanical connection strength can be increased.

(First modification)
As shown in FIG. 7, the laser system according to the first modification of the embodiment of the present invention has an optical coupler 3 at the connection portion between the exit end of the optical coupler 3 and the entrance end of the hole core fiber 4. 6 differs from the configuration of the laser system shown in FIG. 6 in that not only the incident end of the hole core 41 but also the incident ends of the hole portions 42a, 42b, and 42c are blocked.

  The diameter D0 of the emission end of the optical coupler 3 is set to be larger than the diameter D4 of the outermost hole portion 42c of the hole core fiber 4. In other words, the cross-sectional area of the emission end of the optical coupler 3 is set to a size that blocks the outermost hole portion 42 c of the hole core fiber 4.

  Furthermore, in the laser system according to the first modification, the refractive index n1 of the coupling core 33 at the central portion on the emission end side of the optical coupler 3 is determined from the refractive index n2 of the peripheral emission cladding portion 32 surrounding the coupling core 33. Is different from the structure of the laser system shown in FIG. 6 in that the degree of optical coupling from the optical coupler 3 to the hole core fiber 4 is increased.

  Since it is sufficient that the refractive index n2 of the output cladding part 32 is lower than the refractive index n1 of the coupling core 33, the output cladding part 32 may be an air layer. Further, the refractive index n1 of the coupling core 33 and the refractive index n2 of the output cladding portion 32 may not be changed stepwise, but may be a refractive index distribution type structure in which the refractive index changes with an inclination gradient. The “gradient gradient” only needs to be such that the refractive index gradually decreases from the central portion on the output end side of the optical coupler 3 to the periphery. It does not matter if the refractive index changes.

  On the exit end side of the optical coupler 3, the exit ends of the optical fibers 21 to 27 are separated from the entrance end of the hole core fiber 4 and are made of glass or resin so as to be in contact with the exit ends of the optical fibers 21 to 27. A coupling core 33 with a rate n1 is arranged. The coupling core 33 has, for example, a cylindrical shape, and is in contact with the incident end of the hole core fiber 4 so as to close the hole core 41. Further, all of the hole portions 42 a to 42 c are closed by the coupling core 33 and the emission cladding portion 32.

  The ferrule 31 is separated from the coupling core 33 via the output cladding portion 32 on the output end side of the optical coupler 3, and is in contact with the outer peripheral portion of the input end of the hole core fiber 4. On the emission end side of the optical coupler 3, the end of the ferrule 31 and the outer periphery of the hole core fiber 4 are connected by heat fusion, and the end of the ferrule 31 is provided with a fusion part 3 a. Yes.

  Although not shown, the laser system according to the first modification is also connected to the exit end side of the optical coupler 3 and the entrance end side of the hole core fiber 4 as in FIG. A flange may be provided, and the two connection flanges may be coupled by a clamp or the like to increase the mechanical connection strength.

  According to the laser system according to the first modification, the emission end of the optical coupler 3 closes the incident end of the hole core 41 and the hole portions 42a, 42b, and 42c, so that moisture and impurities are holes. Intrusion into the portions 42a, 42b and 42c can also be prevented, and the reliability of the hole core fiber 4 can be improved.

  Further, by setting the refractive index n1 of the coupling core 33 located at the central portion of the output end of the optical coupler 3 to be higher than the refractive index n2 of the peripheral output cladding portion 32, the light is transmitted through the optical coupler 3. The incident light can be easily collected on the coupling core 33 at the exit end of the optical coupler 3, so that the light coupling efficiency can be increased and the output can be easily increased.

(Second modification)
As shown in FIG. 8, the laser system according to the second modification of the embodiment of the present invention has an optical coupler 3 at the connection portion between the emission end of the optical coupler 3 and the incident end of the hole core fiber 4. 6 differs from the structure of the laser system shown in FIG. 6 in that the outer peripheral side of the light emitting end is inserted on the incident end side of the hole core 41 so that the outer peripheral side of the hole end is in contact with the inner wall of the hole core 41.

  In the second modification of FIG. 8, the case where the clad portions of the optical fibers 21, 22, and 25 constituting the optical coupler 3 are all inserted into the hole core 41 is illustrated. It is not always necessary that all of the cladding portions of the fibers 21, 22, and 25 are inserted into the hole core 41. Some of the cladding portions of the optical fibers 21, 22, and 25 are inserted into the hole core 41. It may be a structured. However, all the cores of the optical fibers 21, 22, and 25 of the optical coupler 3 need to be inserted into the hole core 41. Moreover, even if the diameter D0 of the output end of the optical coupler 3 is further smaller and the ferrule 31 constituting the outer peripheral portion of the optical coupler 3 is inserted so as to be in contact with the inner wall of the hole core 41, Good.

(Third Modification)
The laser system according to the embodiment of the present invention may have a structure according to a third modification as shown in FIG. Similar to the second modified example, at the exit end of the optical coupler 3, the exit ends of the optical fibers 21 to 27 are separated from the entrance end of the hole core fiber 4 and contact the exit ends of the optical fibers 21 to 27. As described above, the coupling core (first coupling core) 33 having a refractive index n1 made of glass, resin, or the like is disposed, but the coupling core 33 is separated from the hole core 41. An output cladding part 32 having a refractive index n2 is provided so as to surround the coupling core 33 (n1> n2). At the end portion of the coupling core 33, a coupling core (second coupling core) 34 having a refractive index n1 made of a cylindrical member such as glass is disposed so as to be surrounded by an output cladding portion 32 having a refractive index n2. The cross-sectional area of the coupling core 34 is smaller than the cross-sectional area of the coupling core 33, and the outer periphery of the end of the coupling core 34 is inserted into the incident end of the hole core 41 so as to contact the inner periphery of the hole core 41. .

  In the structure according to the third modification shown in FIG. 9, the output cladding portion 32 may be an air layer because the refractive index n2 of the output cladding portion 32 only needs to be lower than the refractive index n1 of the coupling cores 33 and 34. Further, the refractive index n1 of the coupling cores 33 and 34 and the refractive index n2 of the output cladding part 32 may not be changed stepwise, and the refractive index may be changed with an inclination gradient.

  According to the laser system according to the third modified example, the optical coupling efficiency is improved by inserting at least a part of the emission end of the optical coupler 3 into the incident end of the hole core 41, and further, The incident end of the hole core 41 can be blocked. Thereby, impurities such as moisture and dirt can be prevented from entering the hole core 41, and the characteristic deterioration of the hole core fiber 4 over time due to the impurities entering the hole core 41 is prevented. Can be suppressed. It should be noted that at least a part of the output end of the optical coupler 3 is not inserted into the incident end of the hole core 41, but is held at the position of the incident end of the hole core 41, and the incident end of the hole core 41 is simply set. You may be the structure which closes.

  Although not shown, the laser system according to the third modification is also connected to the exit end side of the optical coupler 3 and the entrance end side of the hole core fiber 4 as in FIG. A flange may be provided, and the two connection flanges may be coupled by a clamp or the like to increase the mechanical connection strength.

(Fourth modification)
As shown in FIG. 10, the laser system according to the fourth modification of the embodiment of the present invention further includes an optically transparent end cap 8 that closes the output end facing the incident end of the hole core fiber 4. It is different from the structure of the structure of the laser system shown in FIG. The end cap 8 covers the entire output end of the hole core fiber 4 while maintaining confidentiality.

  As a material of the end cap 8, for example, a material that is optically transparent to light transmitted through the hole core 41 such as quartz glass can be used. The end cap 8 and the exit end of the hole core fiber 4 are, for example, heat-sealed or bonded.

  In FIG. 10, the end cap 8 is a parallel plate. However, the end cap 8 may be formed of a convex lens or the like, and the end cap 8 may have a function of a condensing lens. If the end cap 8 is a half-convex lens, one surface of the half-convex lens is flat, so that confidentiality is maintained even when the output end of the hole core fiber 4 is cut to a flat surface. The end cap 8 can be heat-sealed or bonded to the exit end of the hole core fiber 4. When the end cap 8 is a biconvex lens, if the output end of the hole core fiber 4 is configured as a concave surface that meets the curvature of the biconvex lens, the exit of the hole core fiber 4 is maintained so as to maintain confidentiality. The end cap 8 can be heat-sealed or bonded to the end.

  According to the laser system according to the fourth modification, the end cap 8 is provided at the exit end of the hole core fiber 4 to completely close both ends of the hole core 41 and the hole portions 42a, 42b, and 42c. Can do. Therefore, moisture and impurities can be prevented from entering the hole core 41 and the hole portions 42a, 42b, and 42c, the deterioration of the hole core fiber 4 with time is further suppressed, and the reliability and stability are more excellent. It is possible to provide a high power laser system.

(Other embodiments)
As described above, the present invention has been described by the embodiment and the first to fourth modifications. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. . From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the embodiment of the present invention and the first to fourth modifications, as shown in FIG. 5, the structure of the hole core fiber 4 having three layers of ring hole portions 42a, 42b, and 42c is used. Although illustrated, the number, position, size, and the like of the hole portions 42a, 42b, and 42c are not particularly limited as long as the hole core fiber 4 has at least the hole core 41. In addition, the hole core fiber 4 is composed of a photonic crystal fiber that has no hole around the hole core 41 and realizes a Bragg reflection condition and a photonic band gap with a periodic structure of refractive index by a polymer or the like. Also good.

  Thus, the present invention can be applied to various laser systems without departing from the scope of the present invention described in the claims.

DESCRIPTION OF SYMBOLS 3 ... Optical coupler 3a ... Fusion | fusion part 4 ... Hole core fiber 8 ... End cap 11-17 ... Light source unit (DDL1-DDL7)
21-27 ... Optical fiber 21a ... Core 21b ... Cladding 31 ... Ferrule 32 ... Outgoing cladding part 33, 34 ... Coupling core 41 ... Hole core 42a, 42b, 42c ... Hole part 43 ... Coating layer 51, 52 ... Connection flange 53 ... Clamp 111-126 ... Laser diode 121-126 ... Diffraction grating

Claims (11)

A plurality of light source units each having a plurality of lasers and respectively outputting primary laser beams obtained by optically combining the outputs of the plurality of lasers;
An optical coupler for optically combining the primary laser light and outputting a secondary laser light;
A hole core fiber that transmits the secondary laser beam output from the optical coupler;
The laser system according to claim 1, wherein an emission end of the optical coupler is plugged with a hole core of the hole core fiber at an incident end of the hole core fiber. The number of the plurality of lasers is n1, the numerical aperture is NA1, the diameter of the plurality of lasers transmitting light is D1, the number of the light source units is n2, the numerical aperture is NA2, and the light source unit is the primary laser beam. , D2 is the numerical aperture of the optical coupler and the hole core fiber NA3, and D3 is the diameter at which the optical coupler and the hole core fiber transmit the secondary laser light.

n1 (NA1 × D1) <n2 (NA2 × D2) <NA3 × D3

The laser system according to claim 1, wherein:   The laser system according to claim 1, wherein a diameter of the emission end is equal to or larger than a diameter of the hole core. The hole core fiber has a hole portion extending in a longitudinal direction of the hole core on an outer periphery of the hole core;
3. The laser system according to claim 1, wherein a cross-sectional area of the emission end is a size that further blocks the hole portion. 4.   5. The laser system according to claim 1, wherein a refractive index of a central portion of the emission end is higher than a refractive index of a peripheral portion surrounding the central portion.   6. The laser system according to claim 1, further comprising a coating layer covering an outer periphery of the emitting end and an incident end of the hole core fiber.   3. The laser system according to claim 1, wherein an outer periphery of the emitting end is inserted on an incident end side of the hole core so as to contact an inner wall of the hole core.   The laser system according to claim 1, wherein the primary laser light is output light of a direct diode laser.   9. The laser system according to claim 1, wherein each of the numerical aperture of the optical coupler and the numerical aperture of the hole core fiber is 0.3 or more.   The laser system according to any one of claims 1 to 9, further comprising an optically transparent end cap that closes an output end of the hole core fiber.   The laser system according to claim 1, wherein a fusion part is provided between the emission end and the incidence end of the hole core fiber.

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