阅读说明：本技术 半导体激光装置 (Semiconductor laser device ) 是由 河崎正人 桂智毅 藤川周一 于 2019-03-29 设计创作，主要内容包括：特征在于,具有：多个半导体激光元件(1011、1012),其射出波长彼此不同的激光(2001、2002)；部分反射元件(104),其与多个半导体激光元件(1011、1012)构成外部谐振器的两端；透射型波长色散元件(103),其在多个半导体激光元件(1011、1012)及部分反射元件(104)之间的激光的光路上,配置于多个激光(2001、2002)重叠起来的位置,具有波长色散性,通过在包含多个激光(2001、2002)的光轴的第1面(XY面)内,使多个激光(2001、2002)的行进方向变化,从而使多个激光共有光轴、进行耦合；以及非对称折射光学元件(105),其配置于透射型波长色散元件(103)及部分反射元件(104)之间的光路上,与包含于第1面(XY面)且与激光的光轴正交的方向即第1朝向(D1)上的位置变化相伴地,从内部通过的距离即元件内通过距离减少。(Characterized in that it comprises: a plurality of semiconductor laser elements (1011, 1012) that emit laser beams having different wavelengths from each other (2001, 2002); a partially reflecting element (104) which forms both ends of the external resonator together with the plurality of semiconductor laser elements (1011, 1012); a transmission-type wavelength dispersion element (103) which is disposed at a position where the plurality of laser beams (2001, 2002) overlap on the optical path of the laser beam between the plurality of semiconductor laser elements (1011, 1012) and the partial reflection element (104), has wavelength dispersion properties, and causes the plurality of laser beams to share an optical axis and to be coupled by changing the traveling direction of the plurality of laser beams (2001, 2002) within a 1 st plane (XY plane) including the optical axes of the plurality of laser beams (2001, 2002); and an asymmetric refractive optical element (105) which is disposed on the optical path between the transmissive wavelength dispersion element (103) and the partially reflective element (104), and which reduces the distance passed from the inside, i.e., the intra-element passing distance, as the position in the 1 st direction (D1), which is a direction perpendicular to the optical axis of the laser beam and is included in the 1 st plane (XY plane), changes.)

1. A semiconductor laser device is characterized by comprising:

a plurality of semiconductor laser elements that emit laser beams having different wavelengths;

a partial reflection element which constitutes both ends of the external resonator together with the plurality of semiconductor laser elements;

a transmission-type wavelength dispersion element having wavelength dispersion properties, which is disposed at a position where the plurality of laser beams overlap each other on an optical path of the laser beams between the plurality of semiconductor laser elements and the partially reflective element, and which couples the plurality of laser beams by sharing an optical axis by changing a traveling direction of the plurality of laser beams in a 1 st plane including the optical axes of the plurality of laser beams; and

and an asymmetric refractive optical element that is disposed on an optical path between the transmission wavelength dispersion element and the partially reflective element, and that reduces an internal passing distance, which is a distance that passes through the inside of the element, as a position of the element changes in a 1 st direction, which is a direction that is orthogonal to an optical axis of the laser beam and is included in the 1 st surface.

2. The semiconductor laser device according to claim 1,

the transmission type wavelength dispersion element is a transmission type diffraction grating.

3. The semiconductor laser device according to claim 1 or 2,

the asymmetric refractive optical element is formed of a material having a higher refractive index than free space,

the 1 st direction is a direction in which a distance from the transmissive wavelength dispersion element to the asymmetric refractive optical element is long and short.

4. The semiconductor laser device according to claim 3,

with the asymmetric refractive optical element, the intra-element pass distance decreases linearly with respect to the distance of the 1 st orientation.

5. The semiconductor laser device according to claim 3,

with the asymmetric refractive optical element, the intra-element pass distance decreases in stages per certain distance traveled in the 1 st orientation.

6. The semiconductor laser device according to any one of claims 1 to 5,

the laser device further includes a divergence angle correction element that is disposed between the semiconductor laser element and the transmission wavelength dispersion element and corrects a divergence angle of the laser beam.

7. The semiconductor laser device according to claim 6,

the optical system further includes a condensing lens disposed on an optical path between the divergence angle correcting element and the transmissive wavelength dispersion element.

8. The semiconductor laser device according to any one of claims 1 to 7,

the optical device further includes a condensing lens disposed on an optical path between the transmissive wavelength dispersion element and the asymmetric refractive optical element.

9. The semiconductor laser device according to any one of claims 1 to 8,

the laser device further includes a rotating optical element disposed on an optical path between the plurality of semiconductor laser elements and the transmission wavelength dispersion element, and configured to emit the plurality of incident laser beams by rotating the plurality of laser beams by 90 degrees independently about an optical axis as a rotation axis.

10. The semiconductor laser device according to any one of claims 1 to 9,

at least a part of the plurality of semiconductor laser elements is constituted by a semiconductor laser array element.

Technical Field

The present invention relates to a semiconductor laser device that couples laser light emitted from a plurality of semiconductor laser elements using a wavelength dispersive optical element.

Background

In the semiconductor laser device, the laser power that can be generated from 1 light emitting point is low, and in applications such as laser processing, it is necessary to use a plurality of semiconductor laser devices in a collective manner. As a technique for collecting laser light from a plurality of semiconductor laser elements, a semiconductor laser device has been proposed in which light beams from a plurality of semiconductor laser elements are coupled to 1 optical axis using an external resonator including a plurality of semiconductor laser elements and a wavelength dispersion optical element. In such a semiconductor laser device, it is a problem to improve the light condensing property of the light beam.

Patent document 1 discloses a semiconductor laser device in which, in an external resonator in which light beams of a plurality of semiconductor laser elements are coupled using a dispersive optical element, cross-coupled oscillation is suppressed by a lens disposed between the dispersive optical element and a partial mirror, and the light condensing property of an output light beam is improved.

Patent document 1: U.S. patent application publication No. 2013/0208361 specification

Disclosure of Invention

However, according to the above-described conventional technique, there is a problem that, although the decrease in the light condensing property due to the cross-coupled oscillation can be alleviated, the decrease in the light condensing property due to a factor other than the cross-coupled oscillation is not effective.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor laser device which couples laser light emitted from a plurality of semiconductor laser elements using a wavelength dispersion optical element, and which generates high-power laser light with high light condensing performance.

In order to solve the above problems and achieve the object, a semiconductor laser device according to the present invention includes: a plurality of semiconductor laser elements that emit laser beams having different wavelengths; a partial reflection element which constitutes both ends of the external resonator together with the plurality of semiconductor laser elements; a transmission-type wavelength dispersion element having wavelength dispersion properties, which is disposed at a position where the plurality of laser beams overlap each other on an optical path of the laser beams between the plurality of semiconductor laser elements and the partially reflecting element, and which couples the plurality of laser beams by sharing an optical axis by changing a traveling direction of the plurality of laser beams in a 1 st plane including the optical axes of the plurality of laser beams; and

and an asymmetric refractive optical element which is disposed on an optical path between the transmission wavelength dispersion element and the partial reflection element, and which reduces a distance that passes through the inside, that is, an in-element passing distance, in accordance with a change in position of a 1 st direction, which is a direction that is included in the 1 st plane and is orthogonal to an optical axis of the laser light.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, in a semiconductor laser device in which laser light emitted from a plurality of semiconductor laser elements is coupled using a wavelength dispersion optical element, the semiconductor laser device can generate laser light having high light condensing performance and high power.

Drawings

Fig. 1 is a schematic diagram showing a structure of a semiconductor laser device according to embodiment 1 of the present invention.

Fig. 2 is a schematic diagram showing an example of a condensing state of an optical system having no aberration.

Fig. 3 is a schematic diagram showing an example of a condensing state of an optical system having aberration.

Fig. 4 is a schematic diagram showing an example of the structure of the asymmetric refractive optical element shown in fig. 1.

Fig. 5 is a schematic diagram showing a configuration of an asymmetric refractive optical element as a modification of fig. 4.

Fig. 6 is a schematic diagram showing a structure of a semiconductor laser device according to embodiment 2 of the present invention.

Fig. 7 is a schematic diagram showing a structure of a semiconductor laser device according to embodiment 3 of the present invention.

Fig. 8 is a schematic diagram showing a structure of a semiconductor laser device according to embodiment 4 of the present invention.

Fig. 9 is a schematic diagram showing the structure of the semiconductor laser array element shown in fig. 8.

Fig. 10 is a schematic diagram showing a structure of a semiconductor laser device according to embodiment 5 of the present invention.

Fig. 11 is a perspective view showing an example of the configuration of the rotating optical element shown in fig. 10.

Fig. 12 is a schematic diagram showing a structure of a semiconductor laser device according to embodiment 6 of the present invention.

Detailed Description

A semiconductor laser device according to an embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.

Fig. 1 is a schematic diagram showing a configuration of a semiconductor laser device 1001 according to embodiment 1 of the present invention. The X, Y, and Z axes of a 3-axis rectangular coordinate system are illustrated in fig. 1.

The semiconductor laser device 1001 includes a plurality of semiconductor laser elements 1011 and 1012 that emit laser beams having different wavelengths. The laser beam 2001 emitted from the semiconductor laser element 1011 enters the transmission wavelength dispersion element 103 via the divergence angle corrector 1021 for correcting the beam divergence angle. The laser light 2002 emitted from the semiconductor laser element 1012 enters the transmission wavelength dispersion element 103 via the divergence angle correction element 1022 for correcting the beam divergence angle.

The semiconductor laser elements 1011 and 1012 constitute one end of the external resonator, and the partially reflecting element 104 constitutes the other end of the external resonator. In other words, the partially reflective element 104 and the semiconductor laser elements 1011 and 1012 form both ends of the external resonator. The transmission wavelength dispersion element 103 is disposed on the optical path of the laser beam between the semiconductor laser elements 1011, 1012 and the partially reflecting element 104, and in the deflection unit 301 including the position where the plurality of laser beams 2001, 2002 are superposed. The transmission wavelength dispersion element 103 changes the traveling direction of the laser beams 2001 and 2002 by wavelength dispersion in the XY plane which is the 1 st plane including the optical axes of the laser beams 2001 and 2002. Thereby, the plurality of laser beams 2001 and 2002 are coupled into 1 beam sharing a common optical axis. The transmissive wavelength dispersion element 103 is, for example, a transmissive diffraction grating, a prism, or the like.

The partial reflection element 104 reflects a part of the laser beams 2001 and 2002 coupled as 1 beam, returns the reflected laser beams to the transmission wavelength dispersion element 103, and outputs the remaining part to the outside of the external resonator. In fig. 1, the partial reflection element 104 reflects a part of the entire beam cross section of the laser beams 2001 and 2002, but may be a mirror (scraper) that passes a part of the beam cross section of the incident light to the outside and reflects the remaining part to form an unstable resonator.

The asymmetric refractive optical element 105 is disposed on the optical path between the transmissive wavelength dispersive element 103 and the partially reflective element 104. In the asymmetric refractive optical element 105, the angle of the emission surface 105a of the asymmetric refractive optical element 105 with respect to the incident light differs depending on the position on the 1 st direction D1, which is a direction orthogonal to the optical axis of the laser light and included in the XY plane. Therefore, the angle change of the exit surface 105a differs depending on the position on the 1 st orientation D1. Therefore, the asymmetric refractive optical element 105 varies the optical path length from the emission surface 105a to the partially reflecting element 104 depending on the position in the 1 st direction D1.

The external optical system 302 includes a condensing lens 302a, and condenses the laser light emitted from the semiconductor laser device 1001 at a condensing point 303. Fig. 2 is a schematic diagram showing an example of a condensing state of an optical system having no aberration. Fig. 3 is a schematic diagram showing an example of a condensing state of an optical system having aberration. As representative of a large number of rays in the light beam, a principal ray 312 passing on the optical axis of the light beam, a lower ray 311 passing from the lower side of the optical axis of the light beam in the lens, and an upper ray 313 passing from the upper side of the optical axis of the light beam in the lens are shown. In the case where there is no aberration, as shown in fig. 2, at the light-converging point 303 formed by the external optical system 302, the principal ray 312, the upper side ray 313, and the lower side ray 311 intersect at 1 point.

In contrast, when there is aberration, as shown in fig. 3, the principal ray 312, the upper ray 313, and the lower ray 311 do not intersect at 1 point at the converging point 303 formed by the external optical system 302. When aberration is present, the light condensing property is reduced, the energy density of the laser beam at the condensing point 303 is reduced, and the beam profile is not targeted.

In the semiconductor laser device 1001 shown in fig. 1, since the optical path lengths of the laser beams 2001 and 2002 are different in the deflection unit 301, the light converging property is lowered as shown in fig. 3 when the asymmetric refractive optical element 105 is not provided. In the semiconductor laser device 1001, the optical path length difference generated in the deflecting unit 301 is reduced by the asymmetric refractive optical element 105. Therefore, the light condensing property of the light beam is improved.

A more detailed configuration of each component of semiconductor laser device 1001 will be described. In the semiconductor laser device 1001 shown in fig. 1, 2 semiconductor laser elements 1011 and 1012 are used, but 3 or more semiconductor laser elements may be used. Here, the semiconductor laser elements 1011 and 1012 are end-face light emitting type single emitting semiconductor laser elements having a fabry-perot resonator. An end-face light-emitting semiconductor laser having a Fabry-Perot resonator has a fast axis with a large beam divergence angle and a slow axis orthogonal to the fast axis and having a small beam divergence angle. In fig. 1, the fast axis is in the XY plane, and the slow axis is the Z-axis direction. The semiconductor laser elements 1011 and 1012 have a wavelength of 400nm to 1100nm, which facilitates fiber coupling, for example, and are commercially available with a longer lifetime than other wavelength bands, particularly around 900nm to 1000nm, and therefore are suitable for high power applications such as laser processing. The semiconductor laser elements 1011 and 1012 according to the present embodiment may be of a surface-emitting type, for example, or a resonator structure may be of a horn type or a folded resonator type.

The laser beams 2001 and 2002 emitted from the semiconductor laser elements 1011 and 1012 enter divergence angle correction elements 1021 and 1022 in the fast axis direction, respectively. The laser beams 2001 and 2002 emitted from the divergence angle correction elements 1021 and 1022 enter the transmission wavelength dispersion element 103.

The laser beams 2001 and 2002 have overlapping beam profiles at the position of the transmission wavelength dispersion element 103. In fig. 1, the beam profiles are superimposed by adjusting the arrangement of the semiconductor laser elements 1011 and 1012 and the transmission type wavelength dispersion element 103. In this way, the arrangement of the plurality of semiconductor laser elements 1011, 1012 may be adjusted to overlap the beam cross-sections, or an optical element may be separately provided on the optical paths of the plurality of laser beams 2001, 2002 to adjust the optical paths to overlap the beam cross-sections.

The transmissive wavelength dispersion element 103 has wavelength dispersion properties in the XY in-plane direction of the laser light. The transmission wavelength dispersion element 103 deflects the plurality of laser beams in the XY plane at an angle depending on the wavelength, thereby coupling the plurality of laser beams into a beam having 1 optical axis in common. When passing through the deflection unit 301, the optical path length varies in the XY plane depending on the position in the beam cross section. Such a difference in optical path length causes a reduction in the light condensing property of the output light beam of the external resonator.

In the asymmetric refractive optical element 105, the internal passage distance, which is the distance that the laser light passes through the inside of the asymmetric refractive optical element 105, decreases with a change in the position of the 1 st direction D1 in the beam cross-sectional direction in the XY plane. The asymmetric refractive optical element 105 shown in fig. 1 is formed of a material having a higher refractive index than free space. In this specification, a region around the semiconductor laser elements 1011 and 1012 and the optical element is referred to as a free space. When the refractive index of the asymmetric refractive optical element 105 is higher than the refractive index of the free space, the 1 st direction D1 is a direction of the outer ray 203 on the long side and the inner ray 201 on the short side from the transmissive wavelength dispersion element 103 to the asymmetric refractive optical element 105, as shown in fig. 1. Further, in the case where the asymmetric refractive optical element 105 is formed of a material having a lower refractive index than that of free space, the 1 st direction D1 is a direction from the inner light ray 201 toward the outer light ray 203.

In fig. 1, a chief ray 202, an inner ray 201, and an outer ray 203 are shown. The chief ray 202 is the optical axis of the laser. The inner ray 201 and the outer ray 203 are geometrical light paths. The inner ray 201 is incident on the transmission wavelength dispersion element 103 at the inner side of the deflection angle than the principal ray 202, and the outer ray 203 is incident on the transmission wavelength dispersion element 103 at the outer side of the deflection angle than the principal ray 202.

When the traveling direction of the laser light is changed by the transmissive wavelength dispersion element 103, the asymmetric refractive optical element 105 functions such that the optical path length to the partially reflective element 104 after passing through the asymmetric refractive optical element 105 is longer than the main beam 202 with respect to the inner beam 201 whose optical path length is shorter than the main beam 202. The asymmetric refractive optical element 105 functions such that the optical path length to the partial reflection element 104 after passing through the asymmetric refractive optical element 105 is shorter than the principal ray 202 for the outside ray 203 whose optical path length becomes longer than the principal ray 202. Thereby, the fluctuation of the light at the condensed point 303 is reduced. That is, the aberration is reduced, and the reduction in the light condensing property of the output light beam can be suppressed.

Fig. 4 is a schematic diagram showing an example of the structure of the asymmetric refractive optical element 105 shown in fig. 1. The asymmetric refractive optical element 105 shown in fig. 4 is a prism having the shape of a triangular prism whose bottom surface is a right-angled triangle. As a constituent material of the prism, for example, an optical material such as synthetic quartz is suitable, and a low reflection coating is formed at the light incident surface and the light exit surface as necessary. The vertex angle θ of the triangle may be set to reduce the optical path difference between the outside ray 203 and the inside ray 201. More preferably, the output light beam having high light condensing property may be obtained by calculating the aberration generated by the deflection unit 301, designing the apex angle θ by taking into account the refractive index of the material of the asymmetric refractive optical element 105, and calculating the in-element passing distance in the asymmetric refractive optical element 105 depending on the position in the cross section so as to compensate the optical path difference between the outer light beam 203 and the inner light beam 201 generated by the deflection unit 301.

The asymmetric refractive optical element 105 is disposed so that a side surface corresponding to a hypotenuse of the right triangle becomes an emission surface. Thus, the in-element pass distance decreases linearly with respect to the travel distance at 1 st orientation D1. In addition, the intra-element passing distance is the same in the Z-axis direction which is a direction orthogonal to the 1 st direction D1.

Fig. 5 is a schematic diagram showing a configuration of an asymmetric refractive optical element 1052 which is a modification of fig. 4. The asymmetric refractive optical element 1052 is a step-shaped element of high refractive material. The shape of the asymmetric refractive optical element 105 is not limited to the examples shown in fig. 4 and 5, and may be different depending on the position in the 1 st direction D1 of the beam profile. The asymmetric refractive optical element 105 is a single optical element in fig. 1, 4, and 5, but may be configured by a plurality of optical elements.

In recent years, the power of processing laser light has been increased, and it has been required to couple light beams from a larger number of semiconductor laser elements in a limited wavelength range. In such a laser device, in order to increase the incident angle of the light beam to the wavelength dispersion element and to improve the wavelength resolution of the wavelength dispersive optical element, it is required to increase the beam diameter on the wavelength dispersion element. The beam angle of incidence is the angle that a ray of light incident on the element makes with the normal to the plane of incidence. In such a laser device, since the light converging property in the 1 st direction D1 shown in fig. 1 is greatly reduced in the direction of wavelength dispersion of the wavelength dispersion element, a great effect can be expected by applying the technique of the above-described embodiment.

For example, in the case where the wavelength of the output light of the semiconductor laser elements 1011 and 1012 is 900nm to 1100nm and the transmission type wavelength dispersion element 103 uses a transmission type diffraction grating in which the number of grooves is 1500 or more/mm, the incident angle of the laser light to the transmission type wavelength dispersion element 103 is 40 degrees or more in an optical arrangement close to, for example, littrow (littrow) type where the diffraction effect is the highest. Under such conditions, since aberration generated in the deflection unit 301 of the transmissive wavelength dispersion element 103 becomes large, a great effect can be expected by applying the technique of the present embodiment. If the beam diameter of the 1 st direction D1 on the transmissive wavelength dispersion element 103 is greater than or equal to 30mm in terms of the edge width, the aberration generated by the transmissive wavelength dispersion element 103 becomes particularly large. Therefore, the aberration reduction effect by applying the technique of the present embodiment becomes large.

Here, when the energy is integrated in the 1 st direction D1 of the beam cross section, the position where the integrated energy is 16% is x1, and the position where the integrated energy is 84% is x2, the knife edge width dx is expressed by the following equation (1).

dx＝2×(x2-x1)…(1)

It has not been known that the aberration in the beam profile generated in the deflection unit 301 described in the present embodiment largely affects the light condensing performance in the wavelength-coupled external resonator. The reason for this is considered that the wavelength-coupling external resonator is developed as a complicated system for coupling a plurality of light beams. In a complicated system in which a plurality of light beams are coupled, there are a plurality of causes of deterioration in light condensing performance such as a difference in characteristics between the light beams subjected to wavelength coupling, an influence of smear (smile) of the semiconductor laser array, and an influence of cross-coupling oscillation. Therefore, it is difficult to separate and analyze them, and no attention is paid to the influence of the aberration generated by the deflection unit 301, and no countermeasure is taken. The inventors of the present invention have provided a solution for the first time with attention paid to the aberration generated by the deflection unit 301.

Further, it is also conceivable that if the asymmetric refractive optical element 105 is disposed in the wavelength coupling external resonator, the light condensing property of the wavelength coupling light beam is reduced due to the wavelength dispersion property of the asymmetric refractive optical element 105. However, in the present embodiment, the reduction in the light condensing property due to the wavelength dispersion property of the asymmetric refractive optical element 105 is sufficiently smaller than the effect of improving the light condensing property due to the asymmetric refractive optical element 105. Specifically, for example, if an optical element made of glass such as quartz glass or SF10 is used and the aberration is eliminated by the difference in the distance passed through the portion made of the glass, the effect of improving the light condensing property can be higher than the reduction in the light condensing property by at least 1 order of magnitude or more.

As described above, in the semiconductor laser device 1001 according to embodiment 1 of the present invention, the distance that the laser light passes through the inside of the asymmetric refractive optical element 105, that is, the intra-element passing distance decreases in the XY plane, which is the 1 st plane, along with the position change in the 1 st direction D1. The optical path length at the deflection unit 301 becomes shorter as going from the outer side to the inner side of the corner of the beam of the laser light 2001, 2002, but by using the asymmetric refractive optical element 105 having the in-element passing distance as described above, the optical path length from the emission surface 105a of the asymmetric refractive optical element 105 to the partial reflection element 104 becomes longer as going from the outer side to the inner side of the corner of the beam of the laser light 2001, 2002. Therefore, the asymmetric refractive optical element 105 can reduce aberration of the semiconductor laser device 1001. Therefore, the semiconductor laser device 1001 can generate laser light having high light-condensing property and high power.

Embodiment 2.

Fig. 6 is a schematic diagram showing a structure of a semiconductor laser device 1002 according to embodiment 2 of the present invention. In addition to the configuration of the semiconductor laser device 1001 shown in fig. 1, the semiconductor laser device 1002 includes a condenser lens 1061 disposed on the optical path between the divergence angle correction element 1021 and the transmission-type chromatic dispersion element 103, and a condenser lens 1062 disposed on the optical path between the divergence angle correction element 1022 and the transmission-type chromatic dispersion element 103. Hereinafter, the same components as those of semiconductor laser device 1001 are denoted by the same reference numerals, and detailed description thereof is omitted, and the description is mainly given of the portions different from semiconductor laser device 1001.

In the semiconductor laser device 1002, when the traveling direction of the laser beams 2001 and 2002 is changed by the transmission-type wavelength dispersion element 103, the optical path length of the inner beam 201 is longer than that of the main beam 202, and the optical path length of the outer beam 203 is shorter than that of the main beam 202, as in the semiconductor laser device 1001. The asymmetric refractive optical element 105 functions to make the optical path length to the partial reflection element 104 after passing through the asymmetric refractive optical element 105 longer than the principal ray 202 with respect to the inner ray 201 having a shorter optical path length than the principal ray 202 by refraction of light. The asymmetric refractive optical element 105 functions to make the optical path length to the partial reflection element 104 after passing through the asymmetric refractive optical element 105 shorter than the principal ray for the outer ray 203 having a longer optical path length than the principal ray 202 by refraction of light. Thus, the transmission type chromatic dispersion element 103 can reduce aberration caused by the optical path length difference between the laser beams 2001 and 2002 occurring in the direction including the 1 st direction D1. Therefore, the reduction in light condensing performance can be suppressed.

In the semiconductor laser device 1002, the beam diameter at the transmission wavelength dispersion element 103 is smaller than that at the semiconductor laser device 1001 by the action of the condenser lenses 1061 and 1062. Therefore, the amount of aberration generated at the deflection unit 301 can be reduced. The beam diameter coupled by the transmissive wavelength dispersion element 103 is also smaller than that of the semiconductor laser device 1001. Therefore, the distance to the light collecting point 303 in the external optical system 302 can be shortened, and the size of the entire optical system can be reduced.

As described above, according to embodiment 2 of the present invention, as in embodiment 1, at least a part of the aberration generated by the deflection unit 301 depending on the position on the 1 st direction D1 in the beam cross section can be compensated. Therefore, a laser beam with high light condensing property and high power can be generated by using the plurality of laser beams 2001 and 2002 emitted from the plurality of semiconductor laser elements 1011 and 1012 by using the element having dispersion property.

Further, by reducing the beam diameter of the laser beams 2001 and 2002 incident on the transmissive wavelength dispersion element 103, the aberration generated by the deflection unit 301 can be reduced at the generation stage.

Embodiment 3.

Fig. 7 is a schematic diagram showing a configuration of a semiconductor laser device 1003 according to embodiment 3 of the present invention. The semiconductor laser device 1003 includes a condenser lens 107 on the optical path between the transmissive wavelength dispersion element 103 and the asymmetric refractive optical element 105, in addition to the configuration of the semiconductor laser device 1001. Hereinafter, the same components as those of semiconductor laser device 1001 are denoted by the same reference numerals, and detailed description thereof is omitted, and the description is mainly given of the portions different from semiconductor laser device 1001.

The condenser lens 107 changes the incident angle and the beam height of the laser beam to the asymmetric refractive optical element 105. Thus, the optical path length difference between the optical paths, which is the cause of the occurrence of the aberration, can be converted into the light collection angle difference and the light beam height difference. Therefore, the asymmetric refractive optical element 105 can be miniaturized. Here, the light ray height refers to the height of a light ray measured in a direction perpendicular to the optical axis from the optical axis.

When the semiconductor laser elements 1011 and 1012 are assumed to be point light sources, in an optical system having no aberration, if the beam height in the direction perpendicular to the principal beam 202 is h and the light collection angle is α, the light in the single beam is collected while maintaining the relationship in which the beam height h is proportional to the tangent tan α of the light collection angle α. In this case, all the rays converge at one point. On the other hand, in the case of an optical diameter having aberration, the relationship between the light height h and the light condensing angle α is broken, and the light is not collected at one point.

In the case where the asymmetric refractive optical element 105 is not provided in front of the partially reflective element 104, the inner ray 201, the principal ray 202, and the outer ray 203 do not converge at a single point at the converging point 303 due to the influence of the optical path length difference generated at the transmissive wavelength dispersion element 103. In contrast, in the present embodiment, by providing the asymmetric refractive optical element 105, the light beam height h and the light collection angle α of each light beam are changed by the refraction action, and the tangent tan α of the light beam height h and the light collection angle α are in a state close to proportional to each other, thereby reducing the aberration. Note that, although the semiconductor laser elements 1011 and 1012 are described as point light sources for simplicity, the same aberration reduction effect as described above can be obtained for laser beams emitted from the actual semiconductor laser elements 1011 and 1012.

As described above, according to embodiment 3 of the present invention, as in embodiment 1, at least a part of the aberration generated by the deflection unit 301 depending on the position on the 1 st direction D1 in the beam cross section can be compensated. Therefore, a laser beam with high light condensing property and high power can be generated by using the plurality of laser beams 2001 and 2002 emitted from the plurality of semiconductor laser elements 1011 and 1012 by using the element having dispersion property.

In addition, in the present embodiment, by converting the optical path length difference between the optical paths, which is a cause of the occurrence of aberration, into the condensing angle difference and the beam height difference using the condensing lens 107, the size of the asymmetric refractive optical element 105 can be reduced compared to embodiments 1 and 2, and the semiconductor laser device 1003 can be downsized.

Embodiment 4.

Fig. 8 is a schematic diagram showing a structure of a semiconductor laser device 1004 according to embodiment 4 of the present invention. The semiconductor laser device 1004 also has the functions of the condenser lenses 1061 and 1062 described in embodiment 2 and the condenser lens 107 described in embodiment 3. Therefore, 2 effects of reduction of aberration by the deflecting unit 301 and miniaturization of the asymmetric refractive optical element 105 can be obtained at the same time.

The semiconductor laser device 1004 uses the semiconductor laser array element 108, in which a plurality of semiconductor laser elements are integrated, as a light source. Therefore, while in embodiment 2 the divergent angle correction elements 1021, 1022 and the condenser lenses 1061, 1062 are provided corresponding to the semiconductor laser elements 1011, 1012, in embodiment 4 the divergent angle correction element 109 and the condenser lens 1063 are provided across the optical paths of the laser beams emitted from the semiconductor laser array element 108.

Fig. 9 is a schematic diagram showing the structure of the semiconductor laser array element 108 shown in fig. 8. The fast axis direction of the semiconductor laser array element 108 coincides with the Z axis direction, and the slow axis direction coincides with the Y axis direction. The semiconductor laser array element 108 has a plurality of light emitting points. Fig. 9 shows light emission directions 401 and 402 from the respective light-emitting points. The semiconductor laser array element 108 shown in fig. 9 emits a plurality of light beams with parallel optical axes. The condenser lens 1063 has a function of overlapping a plurality of light fluxes at a certain position by changing the traveling direction of the plurality of light fluxes in addition to a function of changing the spread angles of the plurality of light fluxes.

In the end-surface emission type semiconductor laser bar, the elements are generally arranged in the slow axis direction, and the divergence angle correcting element 109 which is a cylindrical lens is used as a lens for correcting the beam divergence angle in the fast axis direction. In the present embodiment, the coupling of the light beam by the transmissive wavelength dispersion element 103 is performed in the slow axis direction, and the aberration at the deflection unit 301 is also generated in the slow axis direction. Therefore, the condenser lens 1063, the condenser lens 107, and the asymmetric refractive optical element 105, which contribute to the reduction of aberration, are disposed so as to function in the slow axis direction.

In addition, the semiconductor laser array elements 108 are arranged closely at a narrow pitch. Therefore, more light beams are incident into a narrow angle for wavelength coupling than a single chip laser diode. Therefore, the transmissive wavelength dispersion element 103 requires higher angular resolution. In order to improve the angular resolution of the transmissive wavelength dispersion element 103, the beam diameter on the transmissive wavelength dispersion element 103 needs to be set large. Therefore, the aberration in the beam profile by the deflection unit 301 becomes larger, and the effect of the present invention is exerted more.

As described above, according to embodiment 4 of the present invention, as in embodiment 1, at least a part of the aberration generated by the deflection unit 301 depending on the position on the 1 st direction D1 in the beam cross section can be compensated. Therefore, the laser light having high light-condensing property and high power can be generated by using the plurality of laser light emitted from the semiconductor laser array element 108 using the element having dispersion property.

Further, in the present embodiment, since the condenser lens 1063 and the condenser lens 107 are provided, the effect of reducing the aberration at the deflection unit 301 in the generation stage described in embodiment 2 and the effect of downsizing the asymmetric refractive optical element 105 described in embodiment 3 can be obtained at the same time.

Further, since the semiconductor laser array element 108 on which a plurality of semiconductor laser elements are mounted is used, high-power and high-light-condensing laser light can be generated by a semiconductor laser device having a simple structure and a small number of components.

Embodiment 5.

Fig. 10 is a schematic diagram showing a structure of a semiconductor laser device 1005 according to embodiment 5 of the present invention. In addition to the configuration of the semiconductor laser device 1004 according to embodiment 4, the semiconductor laser device 1005 includes a rotating optical element 110 on the optical path between the divergence angle correcting element 109 and the transmissive wavelength dispersion element 103 in the fast axis direction, and the rotating optical element 110 superimposes the respective light fluxes on the transmissive wavelength dispersion element 103 while rotating the images around the optical axis.

Fig. 11 is a perspective view showing an example of the structure of the rotating optical element 110 shown in fig. 10. The rotating optical element 110 is a 90-degree image rotating optical system array that emits a plurality of laser beams by rotating the laser beams by 90 degrees around an optical axis as a rotation axis. The rotating optical element 110 is disposed in a state of being inclined at 45 degrees with respect to the Y axis in the YZ plane. The rotary optical element 110 is arranged with a plurality of pairs of cylindrical convex lenses in a state of being inclined at 45 degrees with respect to a horizontal axis. The cylindrical convex lenses are arranged at the same pitch as the arrangement pitch of the plurality of light emitting points included in the semiconductor laser array element 108. When the focal length of the cylindrical convex lenses is f, the distance L between the pair of cylindrical convex lenses is 2 f. When a light beam is incident on the rotating optical element 110, the light beam in a state in which the vertical axis direction and the horizontal axis direction are reversed is emitted. Such a rotating optical element 110 is already commercialized and can be easily obtained. International publication No. 2014/087726 also discloses a wavelength-coupled external resonator having a rotating optical element 110, and the same technique can be applied.

An end-face emission type semiconductor laser array element 108 as shown in fig. 9 is often used when a plurality of semiconductor laser elements are used in a row. In such a semiconductor laser array element 108, the light beam divergence angle of the slow axis, which is the arrangement direction of the light emitting points, is generally about 5 degrees to 10 degrees in total, whereas the light beam divergence angle of the fast axis direction orthogonal to the arrangement direction is about 30 degrees to 60 degrees in total. In addition, the slow axis direction is generally lower in light condensing property than the fast axis direction. In the semiconductor laser array element 108, there is deformation of the element called smear caused by the manufacturing process, and sometimes fluctuation in the setting height of the light source occurs in the fast axis direction. In the present embodiment, by rotating the laser beam by 90 degrees around the optical axis using the rotary optical element 110, the influence of the blur in the fast axis direction can be converted to the slow axis direction in which the light condensing property is relatively low.

Thus, the semiconductor laser device 1005 has an effect of suppressing a reduction rate of the light condensing property due to the blur, stably superimposing the outputs of the plurality of semiconductor laser elements, and obtaining a high power.

As described above, according to the semiconductor laser device 1005 according to embodiment 5 of the present invention, as in embodiment 1, it is possible to compensate for at least part of the aberration generated by the deflection unit 301 depending on the position on the 1 st direction D1 in the beam profile. Therefore, the laser light having high light-condensing property and high power can be generated by using the plurality of laser light emitted from the semiconductor laser array element 108 using the element having dispersion property.

In addition, in the present embodiment, since the rotary optical element 110 is used, the influence of the blur in the fast axis direction can be changed to the slow axis direction in which the light condensing property is relatively low. Therefore, it is possible to suppress a decrease in light condensing performance due to blur and stably obtain high power by superimposing outputs of a plurality of semiconductor laser elements.

Embodiment 6.

Fig. 12 is a schematic diagram showing the structure of a semiconductor laser device 1006 according to embodiment 6 of the present invention. The semiconductor laser device 1006 includes a plurality of semiconductor laser array elements 1081 and 1082. The semiconductor laser array elements 1081, 1082 can have the same structure as the semiconductor laser array element 108 shown in fig. 9. Here, 2 semiconductor laser array elements 1081, 1082 are shown, but 3 or more semiconductor laser array elements 108 may be used.

The semiconductor laser device 1006 includes 2 divergence angle correction elements 1091, 1092, and 2 rotating optical elements 1101 and 1102 provided corresponding to the 2 semiconductor laser array elements 1081 and 1082, respectively.

In addition, in order to superimpose the outputs of the plurality of semiconductor laser array elements 1081 and 1082, the light beam enters the transmissive wavelength dispersion element 103 from a wider angle range than in the case of using 1 semiconductor laser array element 108. Therefore, the light beam incident on the transmission wavelength dispersion element 103 at a large incident angle has a large deflection angle at the deflection unit 301, and thus aberration caused by the optical path length difference generated by the deflection unit 301 also becomes large. Therefore, in the semiconductor laser device 1006 having the wavelength-coupled external resonator using the plurality of semiconductor laser array elements 1081 and 1082, the effect of applying the technique of the present embodiment is large.

As described above, according to the semiconductor laser device 1006 according to embodiment 6 of the present invention, as in embodiment 1, at least a part of the aberration generated by the deflection unit 301 depending on the position on the 1 st direction D1 in the beam cross section can be compensated. Therefore, by using the elements having dispersion properties, it is possible to generate high-power laser light having high light-condensing properties by using a plurality of laser light beams emitted from the semiconductor laser array elements 1081 and 1082.

In addition, in the present embodiment, since the plurality of semiconductor laser array elements 1081 and 1082 are used, the effect of enabling higher power to be achieved by coupling laser light output from a larger number of semiconductor laser elements than in the case of using 1 semiconductor laser array element 108 can be obtained.

In the above embodiment, the structures of the semiconductor laser devices 1001 to 1006 have been described, but the technique described in the above embodiment can also be realized as a laser processing device having the semiconductor laser devices 1001 to 1006.

The configurations described in the above embodiments are merely examples of the contents of the present invention, and may be combined with other known techniques, and some of the configurations may be omitted or modified within a range not departing from the gist of the present invention.

For example, although embodiments 4 and 5 described above show an example in which 1 semiconductor laser array element 108 is used as a light source, and embodiment 6 shows an example in which 2 semiconductor laser array elements 1081 and 1082 are used as light sources, the present invention is not limited to the above example. At least a part of the plurality of semiconductor laser elements may be constituted by the semiconductor laser array element 108. That is, the semiconductor laser devices 1004 to 1006 may include both the semiconductor laser array element 108 and the semiconductor laser element that is a single-chip laser diode, without being limited to the example in which all the semiconductor laser elements are the semiconductor laser array element 108. The semiconductor laser devices 1004 to 1006 may have 3 or more semiconductor laser array elements 108.

Description of the reference numerals

103 transmission type wavelength dispersion element, 104 partial reflection element, 105 asymmetric refraction optical element, 105a emitting surface, 107, 302a, 1061, 1062, 1063 condenser lens, 108, 1081, 1082 semiconductor laser array element, 109, 1021, 1022, 1091, 1092 divergence angle correction element, 110, 1101, 1102 rotating optical element, 201 inner light ray, 202 principal light ray, 203 outer light ray, 301 deflection part, 302 outer optical system, 303 condensing point, 1011, 1012 semiconductor laser element, 2001, 2002 laser, D1 1 st orientation, theta apex angle, alpha condensing angle, h ray height.