JP2018056148A - Laser module and laser processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact laser module of high output and high concentration.SOLUTION: A laser module 10 includes multiple laser elements 1 arranged on the same plane of a base 2, and ejecting light beams, respectively, a collimate optical system 3 for collimating the ejected light beams, and a condensing optical system 4 for condensing the collimated light beams. The laser elements 1 are photonic crystal surface emission laser (PCSEL) element. The collimate optical system 3 is configured so that the adjoining light beams, out of the collimated light beams, are emitted in contact with each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser module and a laser processing apparatus including the laser module.

  A conventional laser module includes a plurality of laser elements (semiconductor laser elements) as light sources, a number of collimating lenses (or lens arrays) corresponding to the number of laser elements, and a condensing lens. The emitted light beam is collimated by a collimator lens, condensed by a condenser lens, and coupled to an optical fiber.

  For example, in the laser module disclosed in Non-Patent Document 1, a vertical cavity surface emitting laser (VCSEL) element is used as a laser element, and a light beam emitted from the laser element is collimated by a microlens array and collected. It is disclosed that light is collected using an optical lens.

  In the laser module disclosed in Patent Document 1, a VCSEL element is used as in Non-Patent Document 1, and a plurality of lenses having the functions of a collimating lens and a condensing lens are used. In particular, by using a microlens array integrated as a plurality of lenses, the number of laser elements can be increased and a high output beam can be obtained.

  Non-Patent Document 2 discloses a surface-emitting semiconductor laser element (photonic crystal surface-emitting laser element: PCSEL element) in which a periodic structure (photonic crystal structure) of the same order as the wavelength of light is provided in the vicinity of an active layer. It is disclosed.

Japanese Patent Laying-Open No. 2007-244851 (page 12, lines 1-8, lines 29-31, FIG. 18)

Collimating Diode Laser Beams from a Large-Area VCSEL-Array Using Microlens Array. (Hao-Lin Chen, et al. Photonics Technology Letters, IEEE (Volume: 11, Issue: 5)) Watt-class high-power, high-beam-quality photonic-crystal lasers. (K Hirose, et al. Nphoton. 2014. 75)

  By the way, when performing fiber coupling, if the parallel beams collected by the condensing lens are not in contact with each other, the condensing property of the light beams after fiber coupling is compared to the case in which the parallel beams are in contact with each other. Will drop. Therefore, when a plurality of light beams are combined into a single optical fiber, it is desirable to create parallel beams in contact with each other in order to obtain a combined beam with high light collecting properties.

  In the VCSEL element used in Patent Document 1 and Non-Patent Document 1, the beam size (light emitting area) in the vicinity of the light emitting surface is generally small, thereby increasing the divergence angle of the emitted light beam. Therefore, immediately after the emission, the adjacent light beams are overlapped with each other, and the condensing property of the light beams after the fiber coupling is lowered.

  This problem can be solved by increasing the arrangement interval of the laser elements or by moving the collimating lens away from the laser elements. However, if the arrangement interval of the laser elements is increased, the module is increased in the direction orthogonal to the optical axis. Further, when the collimating lens is moved away from the laser element, the module becomes large not only in the optical axis direction but also in the direction orthogonal to the optical axis due to the large divergence angle of the light beam. Therefore, in order to produce parallel beams in contact with each other, it is necessary to sufficiently shorten the installation position and focal length of the collimating lens.

  However, if the focal length of the collimating lens is shortened, the curvature increases, so that the required accuracy of lens production increases. In addition, when a short focus lens having a focal length of about 1 mm or less is used, it is necessary to suppress aberration by using an aspheric lens. However, it is difficult to manufacture an aspheric lens with high accuracy, which is not preferable.

  Further, when the focal length of the collimating lens is shortened, the influence of the positional deviation of the collimating lens on the deviation of the light beam emission direction increases, and fine adjustment is necessary in the alignment of the collimating lens. Therefore, alignment is performed while observing the light beam that has passed through the collimating lens array in a state where power is supplied to the laser element to emit the light beam, and the adjustment of the optical system becomes complicated. Has occurred. At the same time, it means that problems such as a decrease in output due to the displacement of the optical elements are likely to occur after the laser module is mounted on the mount member.

  Further, it is known that the VCSEL element has a deteriorated light collecting property when the light emitting area is increased. If the output is increased while the light emitting area is small, the energy density on the light emitting surface increases, leading to the destruction of the laser element. Therefore, a VCSEL element having a small light emission area is not suitable as a high-power and high-condensation laser light source.

  The above problem also occurs when an edge emitting semiconductor laser (EEL) is used as the laser element.

  As described above, in the prior art, it is difficult to achieve high output while maintaining high light condensing performance in terms of light source restrictions and optical system adjustment, and semiconductor laser arrays are used for applications that require high output such as sheet metal cutting. It was difficult.

  An object of the present invention is to realize a small, high-output and high-concentration laser module.

  A laser module according to the present invention includes a plurality of laser elements that are arranged on the same plane and emit light beams, a collimating optical system that collimates the light beams emitted from the plurality of laser elements, and a collimating optical system. A condensing optical system that condenses the collimated light beam to form a combined beam. The laser element is a photonic crystal surface emitting laser (PCSEL) element. The collimating optical system is configured to emit light in a state where adjacent light beams are in contact with each other among the collimated light beams.

  According to the present invention, by using a photonic crystal surface emitting laser element having a large light emitting area and a small divergence angle, it is possible to realize a small, high output and high condensing laser module.

It is a block diagram which shows the laser module by Embodiment 1 of this invention. It is the figure which looked at the base where a plurality of laser elements are arranged from the emission direction of the light beam. It is sectional drawing which shows the exemplary structure of a PCSEL element. It is a figure which shows the behavior of the light inside a photonic crystal layer. It is a figure which shows the behavior of the light inside a photonic crystal layer, Fig.5 (a) shows in-plane resonance of light, FIG.5 (b) shows the surface extraction of light. It is a block diagram which shows the laser module by Embodiment 2 of this invention. It is a block diagram which shows the laser module by Embodiment 3 of this invention. It is a figure which shows the compound lens of the laser module by the modification of Embodiment 3 of this invention. It is a figure for demonstrating lighting control of the laser element performed with the laser module by Embodiment 4 of this invention. It is a figure which shows intensity distribution of the light beam of highly focused Gaussian mode (a), donut type (b), and top hat type (c). It is a figure for demonstrating the polarization control of the combined beam performed with the laser module by Embodiment 5 of this invention. It is a figure for demonstrating the polarization control of the combined beam performed with the laser module by Embodiment 5 of this invention. It is a block diagram which shows the laser processing apparatus by Embodiment 6 of this invention. It is a figure which shows arrangement | positioning of the laser element suitable for a laser processing apparatus. (A) A plano-convex lens with a long focal length, (b) a plano-convex lens with a short focal length.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or similar components are denoted by the same reference numerals, and redundant description is omitted.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a laser module according to Embodiment 1 of the present invention.
The laser module 10 includes a plurality of laser elements 1, a collimating lens array 3, a condensing lens 4, and the like. For example, the laser module 10 is mounted on a mount member (not shown) together with the optical fiber 20 and is configured to couple a laser beam (light beam) emitted from the laser module 10 to the optical fiber 20. Yes. The laser module 10 is used for material processing (cutting processing or welding of metal, glass, carbon fiber reinforced plastic (CFRP), resin, etc., welding), optical communication, and the like.

  The plurality of laser elements 1 are mounted on the main surface (the same plane) of the base 2, and each emits a light beam. The laser element 1 is a photonic crystal surface emitting laser (PCSEL) element. The base 2 is plate-shaped, but may include a cooling mechanism for cooling the laser element, a power supply circuit for supplying power to the laser element, and the like. As shown in FIG. 2, the plurality of laser elements 1 are arranged in a hexagonal lattice shape, and thereby the emitted beams are arranged densely.

  2 schematically shows the arrangement of the laser elements 1, and the shape, number, and arrangement interval of the laser elements are not limited to this. For example, in FIG. 2, the laser element 1 is illustrated as a circle, but other shapes such as a rectangle and a hexagon may be used. In FIG. 2, the laser elements 1 are two-dimensionally arranged, but may be arranged one-dimensionally.

  The collimating lens array 3 converts the light beam emitted from each laser element 1 into a parallel beam. In the collimating lens array 3, a plurality of collimating lenses corresponding to the number of the laser elements 1 are integrated so that the light beams emitted from the plurality of laser elements 1 are received on the same axis. In the collimating lens array 3, the collimating lenses are arranged in a hexagonal close-packed manner corresponding to the plurality of laser elements 1 being arranged in a hexagonal lattice shape. The collimating lens array 3 is disposed at a position where adjacent light beams are in contact (or substantially in contact) with each other. At this time, the distance between the laser element 1 and the collimating lens array 3 is determined based on the divergence angle of the light beam and the beam diameter on the light emitting surface of the laser element 1.

  Due to the configuration of the collimating lens array 3, the light beams are emitted from the collimating lens array 3 in a state where adjacent light beams of the parallel beams are in contact with each other.

  Here, that the light beams are in contact with each other means that the beam diameter of the light beams matches the effective diameter of each lens included in the collimating lens array 3. In general, the beam diameter of the light beam is 1 / e2 (13.5%) of the peak value (or the value on the optical axis) of the radiation intensity of the light beam on a plane orthogonal to the optical axis. However, the “beam diameter” in the embodiment of the present invention is not limited to the size defined in this way, and depends on the required energy extraction rate of the light beam. Can be changed.

The condensing lens 4 condenses a plurality of parallel beams emitted from the collimating lens array 3 toward the coupling end surface of the core of the optical fiber 20. Since the adjacent light beams of the parallel beams emitted from the collimating lens array 3 are in contact with each other, the adjacent light beams are also in contact with each other with respect to the combined beam formed by the condenser lens 4. Here, the incident angle θ of the light beam at the time of fiber coupling needs to be a value equal to or _smaller than the maximum light receiving angle θ _max corresponding to the NA (numerical aperture) of the optical fiber 20. The focal length of the condensing lens 4 is determined based on the distance between the condensing lens 4 and the optical fiber 20 so that the incident angle θ is equal to or smaller than the maximum light receiving angle θ _max .

  The collimating lens array 3 is an example of a collimating optical system, and the condensing lens 4 is an example of a condensing optical system. For example, a plurality of collimating lenses may be used as the collimating optical system, or a lens that functions as a collimating optical system and a condensing optical system may be used.

  The combined beam emitted from the laser module 10 is fiber-coupled with adjacent light beams in contact with each other. Thereby, the condensing property of the light beam after fiber coupling improves. The plurality of light beams incident on the optical fiber 20 propagate through the core of the optical fiber 20 and are combined into one light beam, and are emitted from the emission end face of the optical fiber 20 as a high energy light beam.

  By transmitting the light beam to the outside using the optical fiber 20 as in the first embodiment, a complicated beam transmission optical system is not required, which is convenient for various applications. In addition, the intensity distribution before fiber coupling is made uniform in the course of fiber transmission, so that the beam quality can be improved. In particular, the fiber transmission realizes the rotational symmetry of the light beam, which is an important factor for two-dimensional laser processing.

Next, the PCSEL element will be described.
The PCSEL element is a surface emitting semiconductor laser element in which a photonic crystal structure having a period similar to the wavelength of light is provided in the vicinity of an active layer, and can emit uniform coherent light. By adjusting the semiconductor material used for manufacturing the PCSEL element and the period of the photonic crystal structure, the wavelength of the light beam emitted from the PCSEL element can be controlled.

  Specifically, in the conventional laser diode, the transverse mode of the emitted beam changes according to the area of the light emitting surface, and the light beam condensing performance decreases as the light emitting surface is increased for higher output. was there. On the other hand, it is known that the PCSEL element can increase the output while maintaining a high light collecting property even if the light emitting surface is enlarged. As for the longitudinal mode, a conventional laser diode emits a light beam having a wavelength in a certain region corresponding to the gain width of the active layer, whereas a PCSEL element has a single mode defined by the lattice constant of the photonic crystal. Only a light beam of one wavelength is emitted.

FIG. 3 is a cross-sectional view illustrating an exemplary structure of a PCSEL element. In FIG. 3, the light beam emission direction is defined as the z direction, the + z side is the front side, and the −z side is the back side.
As a material of the stacked body 100, for example, GaAs (gallium arsenide) is used. The PCSEL element is provided in a window formed by the laminated body 100, a window electrode 110 provided on the surface of the laminated body 100, a back electrode 120 provided on the back surface of the laminated body 100, and the window electrode 110. And an anti-reflection (AR) coating layer (anti-reflection coating) 130. This window portion becomes a light beam emission surface (light emission surface).

  The stacked body 100 includes a substrate 101, an n-type cladding layer 102, an active layer 103, a carrier block layer 104, a photonic crystal layer 105, a p-type cladding layer 106, and a p-type contact layer 107. The carrier block layer 104 is an undoped layer. In the photonic crystal layer 105, holes 105b are formed in the slab layer denoted by reference numeral 105a. The lattice shape of the photonic crystal layer 105 is arbitrary such as a square lattice, a triangular lattice, or an orthogonal lattice.

  In the configuration of the PCSEL element, the order of the active layer 103, the carrier block layer 104, and the photonic crystal layer 105 may be reversed.

  When a bias voltage is applied between the window electrode 110 and the back electrode 120, light is emitted from the active layer 103, modulated by the photonic crystal layer 105, and emitted as a laser beam in a direction perpendicular to the substrate surface (z direction). Is done.

  The oscillation wavelength of the laser is determined by the material and period of the photonic crystal. In the PCSEL element, the refractive index of GaAs used for the photonic crystal layer 105 is about 3.5, and the refractive index of air holes (air) is 1. Considering the volume occupied by the holes 105b (16%) and the laminated structure of the PCSEL elements, the effective refractive index in the vicinity of the active layer 103 is about 3.3. At this time, the period of the photonic crystal is 980 nm / 3.3≈295 nm. However, this period changes according to the laminated structure of the laminated body 100 or the like.

Next, an exemplary method for manufacturing a PCSEL element (including steps S1 to S4) will be briefly described.
(S1) On the back surface of the substrate 101, the n-type cladding layer 102, the active layer 103, the carrier block layer 104, and the slab layer 105a are epitaxially grown by, for example, metal organic chemical vapor deposition (MOCVD).
(S2) The photonic crystal layer 105 is formed by patterning a resist on the slab layer 105a and etching the slab layer 105a by, for example, reactive ion etching (RIE) to form holes 105b.
(S3) On the back surface of the photonic crystal layer 105, the p-type cladding layer 106 and the p-type contact layer 107 are epitaxially regrown by, for example, metal organic vapor phase epitaxy.
(S4) The window electrode 110 is provided on the surface of the n-type cladding layer 102, and the back electrode 120 is provided on the back surface of the p-type contact layer 107 by vapor deposition.

Next, the principle by which the PCSEL operates as a surface emitting laser light source will be described with reference to FIGS. 4 and 5 showing the behavior of light inside the photonic crystal.
FIG. 4 is a top view of the photonic crystal layer 105. In FIG. 4, for example, the shape of the hole 105b is a perfect circle. Since the photonic crystal layer 105 is located in the vicinity of the active layer 103, the photonic crystal layer 105 exhibits a binding action on the light generated in the active layer 103. The lattice shape of the photonic crystal is arbitrary, but here it is assumed that it is a square lattice shape that is easy to design. The lattice constant of the photonic crystal is equal to the wavelength λ of light generated in the active layer 103.

  For example, consider a case where light 201 having a wavelength indicated by an arrow in FIG. When the lattice constant of the photonic crystal is λ, the light 201 is diffracted in the direction of 90 ° or 180 ° as shown in FIG. 4B, and diffracted light 2021 and 2022 are generated, respectively. The diffracted lights 2021 and 2022 are further diffracted in the direction of 90 ° or 180 ° as shown in FIG. 4C, and diffracted lights 2031 and 2032 are generated, respectively. In FIG. 4C, it can be seen that the diffracted light 2021 and the diffracted light 2032 and the diffracted light 2022 and the diffracted light 2032 interfere with each other to form a standing wave. As described above, diffraction in the 90 ° and 180 ° directions is repeated, and the diffracted light interferes with each other, so that a standing wave along the crystal direction is generated inside the photonic crystal. As a result, light is confined and light resonance occurs in the active layer 103.

  By the way, although the diffraction in the plane where the photonic crystal is formed is considered in FIG. 4, of course, constructive interference also occurs in the direction perpendicular to the photonic crystal plane. As a result, the light confined within the plane and resonated is extracted as a laser beam in the direction perpendicular to the plane.

  FIG. 5A is a diagram corresponding to FIG. 4C and shows in-plane resonance of light. Diffracted lights 301 and 302 having an optical path difference equal to twice the wavelength λ interfere with each other. In FIG. 4, the shape of the hole 105b is a perfect circle, but in FIG. 5A, it is a triangle. It has been found that by making the shape of the air holes 105b triangular, the beam quality is improved as compared with the case of a perfect circle. FIG. 5B shows the direct extraction of the light. Diffracted lights 303 and 304 having an optical path difference equal to the wavelength λ interfere with each other.

  Note that in the PCSEL element, the light beam is emitted in the two-sided direct direction (two directions). In the case where the light beam only needs to be emitted from one direction, the light reflection by the back electrode 120 is used as in the PCSEL element. The light beam is emitted only from the surface side.

  Next, advantages of the first embodiment will be described.

  First, in a VCSEL element using a conventional laser module, the light emission area is as small as about several μm square. Accordingly, adjacent light beams of the light beams emitted from the VCSEL element overlap each other at a position of several mm or less after the emission. Therefore, in order to produce parallel beams in contact with each other, it is necessary to shorten the installation position and focal length of the collimating lens from several hundred μm to several mm.

  For example, in the VCSEL array described in Non-Patent Document 1, 40 × 40 VCSEL elements are arranged in a 1 cm × 1 cm region with a vertical and horizontal 0.25 mm pitch. In order to collimate the light beam emitted from the VCSEL array, a microlens array having a focal length of 0.776 mm and a curvature radius of 0.357 mm is used.

  On the other hand, the light beam emitted from the PCSEL element has a light emitting area of several hundred μm square or more and a divergence angle as small as about 1 degree. Therefore, the distance between the laser element 1 and the collimating lens array 3 and the focal length of the collimating lens array 3 are several to several tens mm while the size in the direction orthogonal to the optical axis of the laser module 10 is kept small. It can be as large as 100 mm. At this time, since collimated lens arrays 3 emit parallel beams in contact with each other, it is possible to obtain a combined beam with high light condensing performance.

  For example, as in the configuration of Non-Patent Document 1, consider a case where a plurality of laser elements 1 are arranged at a pitch of 0.25 mm. For example, when considering a PCSEL element having a light emitting area of 0.2 mm square and operating in a transverse single mode, the light beam emitted from the adjacent laser element 1 propagates by about 12.3 mm until it comes into contact. Therefore, the focal length of the collimating lens is also about 12.3 mm, which can be increased by 10 times or more compared with 0.776 mm in the case of Non-Patent Document 1.

  As described above, according to the first embodiment, since the focal length of the collimating lens array 3 can be increased, the curvature of the lens does not increase as in the case where a VCSEL element is used. Does not increase. In addition, since it is not necessary to consider the influence of aberration, it is not necessary to use an aspheric lens that is difficult to manufacture with high accuracy. Further, the problem that the adjustment of the optical system becomes complicated is also solved.

  Here, when combining light beams, the beam width of each light beam is expanded to the same extent as the width of each collimating lens, and parallelization is performed. Manufacturing accuracy is also important. In a collimating lens array with a short focal length, the curvature of each lens becomes large. Therefore, when manufacturing a lens array in which lenses are arranged closely, there is a problem that the manufacturing accuracy of the indented portion of the lens array decreases. .

  FIG. 15 shows two types of plano-convex lens arrays as an example. In the long focal length lens array shown in (b), the angle of the concave portion Vb at the lens boundary is large and shallow, whereas in the short focal length lens array shown in (a), 2 ° The angle of the indentation portion Va at the boundary between the two curved surfaces is small and a deep indentation. Therefore, the manufacturing accuracy is reduced in a lens array having a short focal length.

  Furthermore, as described above, in the PCSEL element, even when the light emitting area is increased, a high output and high condensing laser can be achieved while maintaining high light condensing property, which is difficult to realize with the conventional technology. Module 10 is realized.

Embodiment 2. FIG.
FIG. 6 is a block diagram showing a laser module according to Embodiment 2 of the present invention.

  When mounting a plurality of laser elements 1 on the base 2, if the arrangement (position, angle) of each other is shifted, the emission position and emission angle of the light beam may be shifted from each other.

  Therefore, in the second embodiment, a plurality of laser elements (discrete elements) 1 shown in FIG. 1 are integrated as a laser element array 11 on a single semiconductor substrate. This utilizes the characteristic that PCSEL elements can be manufactured by a semiconductor manufacturing process and can be simultaneously manufactured and integrated on a single semiconductor substrate.

  According to the second embodiment, since the arrangement of the plurality of laser elements 1 is not shifted from each other, the emission positions and emission angles of the light beams emitted from the plurality of laser elements 1 can be made uniform.

Embodiment 3 FIG.
FIG. 7 is a block diagram showing a laser module according to Embodiment 3 of the present invention.

  Unlike the conventional semiconductor laser, the PCSEL element can increase the output while maintaining a high light collecting property in principle. In the PCSEL element, in principle, the output and the light emission area are substantially proportional, and attempts have been made to increase the output by increasing the light emission area. For example, Non-Patent Document 2 reports a CW (continuous oscillation) output of 0.5 W in a single mode from an emission surface of 0.2 mm × 0.2 mm. For example, a 1 mm × 1 mm PCSEL element has an output of 10 W, and can be applied to metal processing applications.

  However, when this laser element is actually modularized, an arrangement interval of about 2 mm may be required for power supply, cooling, and the like. In this arrangement, in order to bring adjacent light beams into contact with each other with a collimating lens, the distance between the laser element and the collimating lens and the focal length of the collimating lens need to be about 110 mm.

  Increasing the focal length of the collimating lens facilitates alignment of the optical system, but the optical path length needs to be extended when the output of the laser module is changed, so that there remains a problem in scalability. Moreover, there is a possibility that the whole module becomes large.

  Therefore, in the third embodiment, in the laser module 10, the concave lens array 5 is disposed between the plurality of laser elements 1 and the collimating lens array 3. The concave lens array 5 has a function of expanding the beam diameter (beam divergence angle) of each light beam emitted from the plurality of laser elements 1. That is, the concave lens array 5 and the collimating lens array 3 constitute a beam expander (beam expanding optical system).

  According to the third embodiment, by increasing the beam diameter of the light beam using the concave lens array 5, it is possible to prevent an increase in the optical path length and an increase in the size of the laser module 10 due to an increase in output.

  For example, the concave lens array 5 in which the same number of concave lenses (focal length 5.5 mm) as the laser elements are integrated at a position of 5.5 mm from the laser element array 11 where the laser elements are arranged at a pitch of 2 mm is used. Provided to be coaxial with the beam. As a result, the beam divergence angle is expanded, and as a result, adjacent light beams come into contact with each other at a position of about 12.3 mm from the laser element array 11. By arranging the collimating lens array 3 having a focal length of 12.3 mm at this position, it is possible to configure a multiplexing optical system of a high output module while maintaining the same optical path length as the optical system exemplified in the first embodiment. It is. With this configuration, it is possible to prevent an increase in the size of the optical system.

  The focal length of the lens exemplified in the third embodiment is several mm or more, which is sufficiently larger than the focal length of 0.776 mm of the collimating lens described in Non-Patent Document 1. Therefore, the focal length of the third embodiment is as follows. The configuration does not hinder the effect described in the first embodiment (the optical system can be easily aligned). In addition, by appropriately designing the focal lengths of the concave lens array 5 and the collimating lens array 3, the size of the module can be further reduced.

  In the third embodiment, the laser element array 11 is used as the laser module 10 shown in FIG. 7, but a plurality of laser elements (discrete elements) 1 shown in FIG. 1 may be used.

FIG. 8 is a view showing a compound lens of a laser module according to a modification of the third embodiment of the present invention.
In this modification, the concave lens array 5 and the collimating lens array 3 are integrated as one compound lens 15. The light beam L _IN incident on the composite lens 15 is expanded in the compound lens 15, and emits collimated in a state of contact with each other (the light beam L _OUT).

Embodiment 4 FIG.
A laser module according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram corresponding to FIG. 14 described later. Configurations not shown in FIG. 9 in the fourth embodiment are the same as those in the first embodiment.

  In the fourth embodiment, the laser module 10 includes a control device 40 configured to selectively turn on / off each of the plurality of laser elements 1. By performing lighting control of the laser element 1 using the control device 40, the beam profile of the combined beam is controlled. The control device 40 includes a storage unit that stores a lighting control pattern of each laser element 1, a processing unit that performs lighting control, and the like.

Here, M ² is known as a quantity representing the beam quality. It is possible to calculate M ² = πd ₀ θ / λ, where λ is the wavelength of the light beam, d _{0 is} the radius of the light beam at the beam waist, and θ is the half angle of the light beam in the far field. When comparing light beams having the same beam diameter, the smaller the M ² value, the smaller the beam divergence. In the plurality of laser elements 1 shown in FIG. 9, the value of M ² can be made closer to 1 by turning on the laser element 1 closer to the center and turning off the surrounding laser element 1.

In Figure 9, the broken line 401, dashed line 402, the two-dot chain line 403, ^M 2 ^{~9, M} 2 ~11 ^{respectively,} showing the lighting range equivalent to M 2 to 13. By turning on only the laser element 1 within the lighting range, the value of M ² can be changed according to the application of the laser module 10.

  Even when the laser module 10 is used for the same laser processing, the optimum beam shape varies depending on the processing application. For example, a highly focused Gaussian mode light beam whose intensity distribution is shown in FIG. 10A is suitable for cutting a thin metal plate, and therefore only the laser element 1 near the center needs to be lit. On the other hand, a donut-shaped light beam whose intensity distribution is shown in FIG. 10B is suitable for cutting a thick metal plate. Therefore, the laser element 1 near the center is turned off and the surrounding laser elements 1 are turned on. You can do it. When a top hat type light beam having an intensity distribution shown in FIG. 10C is required, all the laser elements 1 may be turned on.

  According to the fourth embodiment, by selectively turning on the laser element 1 and controlling the beam profile of the combined beam, the light collecting property is excellent without mechanical change such as switching of the optical system. In addition, it is possible to obtain a light collection intensity distribution suitable for each processing application.

Embodiment 5. FIG.
A laser module according to the fifth embodiment of the present invention will be described with reference to FIGS. In the fifth embodiment, configurations not shown in FIGS. 11 and 12 are the same as those in the first embodiment.

  In general, in the interaction between light and a substance, characteristics such as absorptance change depending on the polarization state of light. Therefore, in the fifth embodiment, the polarization control of the combined beam is performed by configuring each laser element 1 so as to emit light beams having different polarization directions. The direction of polarized light emitted by each laser element 1 changes according to the shape of the hole 105 b formed in the photonic crystal layer 105. For example, by making the shape of the hole 105b elliptical, the polarization direction can be aligned with the major axis direction of the ellipse.

  When each laser element 1 is arranged so that the polarization direction emits a light beam represented by an arrow 501 in FIG. 11A, the combined beam 502 is a light beam as indicated by an arrow 503 in FIG. It becomes polarized light (azimuth polarized light) along the peripheral direction of the axis. When using azimuth polarized light for laser drilling, the S-polarized light with low absorptance and high reflectivity is incident on the inner wall of the keyhole, increasing the beam arrival rate to the bottom surface of the keyhole, and processing deep holes. It can be suitably performed.

  When the laser elements 1 are arranged so as to emit a light beam whose polarization direction is represented by an arrow 601 in FIG. 12A (orthogonal to the arrow 501 in FIG. 11A), the combined beam 602 is provided. Becomes polarized light (radial polarized light) along the radial direction from the optical axis as indicated by an arrow 603 in FIG. When using radially polarized light for laser cutting, P-polarized light having a high absorptance is incident on the keyhole, so that the material cutting performance is improved.

  The central laser element 1 may be removed as necessary.

  Also, a set of laser elements that produce azimuth polarization and a set of laser elements that produce radial polarization are mounted on the base 2 in a mixed state, and are combined using the control device 40 described in the fourth embodiment. The polarization state of the beam can be electrically switched. This makes it possible to perform laser processing using a light beam suitable for the application.

  In the fifth embodiment, the example in which the combined beam is an axially symmetric polarized beam (azimuth polarized light, radial polarized light) has been described. However, other polarization states (for example, straight lines and circles) may be used depending on the application.

Embodiment 6 FIG.
FIG. 13 is a block diagram showing a laser machining apparatus according to Embodiment 6 of the present invention.
The laser processing apparatus 1000 includes a laser module 10 according to any one of the first to fifth embodiments or any combination thereof, an optical fiber 20 that transmits a light beam emitted from the laser module 10, and light emitted from the optical fiber 20. And a processing head 30 for irradiating the workpiece W with the beam.

  The processing head 30 is a hollow cylindrical member and includes processing lenses 31 and 32 that collimate and collect a light beam to form a light spot at a processing point of the workpiece W. The tip of the processing head 30 is formed in a nozzle shape so that the light beam collected by the processing lens 32 passes and the assist gas is supplied toward the workpiece W.

Next, the arrangement of the laser elements 1 suitable for the laser processing apparatus 1000 according to the sixth embodiment will be described with reference to FIG.
For example, in a sheet metal cutting laser, a carbon dioxide gas laser or a fiber laser having an output of about 1 kW to about 6 kW and a light collecting property of about 4 mm · mrad is often used. At this time, for example, consider using a PCSEL element that oscillates vertically and horizontally in a wavelength band of 900 nm as a light source. At this time, when the multiplexing optical system described in the first to fifth embodiments is used, as shown in FIG. 14, 11 laser elements 1 are arranged in a hexagonal lattice shape in the diameter direction, thereby collecting light of about 4 mm · mrad. Can be realized. If 9 to 13 laser elements 1 are arranged in the diametrical direction, a light beam having a condensing property suitable for sheet metal cutting can be obtained.

  In the arrangement shown in FIG. 14, when the laser element 1 having an output of 10 W is used, the laser output of the laser module 10 is about 1 kW. More than four times the combined beam emitted from the laser module 10 by using polarization coupling that superimposes two light beams having orthogonal polarizations and wavelength coupling that superimposes two or more light beams having different wavelengths. By superimposing the light beam, it is possible to obtain a light beam having the same output (about 1 kW to about 6 kW) and condensing performance as a conventional sheet metal cutting laser.

  Further, for example, in metal welding using a laser beam, a laser having a light collecting property of about 8 mm · mrad to about 12 mm · mrad is often used. As in the case of the sheet metal cutting process, by using a laser module in which 25 to 41 laser elements 1 are arranged in the diameter direction, a light beam having a condensing property suitable for metal welding can be obtained.

  Although FIG. 14 shows a structure in which 91 laser elements 1 are arranged in a hexagonal lattice shape, the laser element 1 may be arranged in a shape close to a circle in which a hexagonal shape swells outward on the side. Good.

  While the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment. Further, another embodiment may be configured by arbitrarily combining the features of the embodiments. In addition, various modifications and improvements may be added to the above-described embodiment, and therefore there are various modifications in the present invention.

  For example, in the above-described embodiment, an example in which a plurality of laser elements 1 emit light beams with the same wavelength has been described, but light beams with different wavelengths may be emitted. It is known that among several wavelengths used for laser processing, for example, a light beam having a wavelength of 808 nm is easily absorbed by aluminum. Therefore, the workability of a workpiece made of aluminum can be improved by combining an element that emits a light beam with a wavelength of 808 nm with another element.

DESCRIPTION OF SYMBOLS 1 Laser element (PCSEL element), 2 Base, 3 Collimate lens array, 4 Condensing lens, 5 Concave lens array, 10 Laser module, 11 Laser element array, 15 Compound lens, 20 Optical fiber

Claims (9)

A plurality of laser elements arranged on the same plane, each emitting a light beam;
A collimating optical system for collimating light beams emitted from the plurality of laser elements;
A condensing optical system that condenses the light beam collimated by the collimating optical system and forms a combined beam;
The laser element is a photonic crystal surface emitting laser element,
The collimating optical system is configured to emit light in a state where adjacent light beams out of the collimated light beams are in contact with each other. The plurality of laser elements are arranged in a hexagonal lattice pattern,
The laser module according to claim 1. The plurality of laser elements are integrated on a single semiconductor substrate,
The laser module according to claim 1. It is disposed between the plurality of laser elements and the collimating optical system, and includes a concave lens array that expands a beam diameter of a light beam emitted from the plurality of laser elements.
The laser module according to any one of claims 1 to 3. The concave lens array and the collimating optical system are integrated as a compound lens,
The laser module according to claim 4. Each of the plurality of laser elements is selectively turned on, and includes a control device that controls a profile of the combined beam.
The laser module according to any one of claims 1 to 5. At least some of the plurality of laser elements emit light beams having different polarization directions so that the combined beam becomes an axially symmetric polarized beam,
The laser module according to claim 1. The laser module according to any one of claims 1 to 7,
An optical fiber that receives the light beam collected by the condensing optical system on one end side and transmits the light beam to the outside;
A laser processing apparatus comprising: a processing head for irradiating a workpiece with a light beam emitted from the optical fiber. A plurality of laser elements arranged on the same plane, each emitting a light beam;
A collimating optical system for collimating light beams emitted from the plurality of laser elements;
A condensing optical system for condensing the light beam collimated by the collimating optical system;
A laser module comprising: a control device that selectively turns on each of the plurality of laser elements and controls a profile of the combined beam.

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