JP2014120621A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device capable of generating a high-convergent and high-efficient light beam.SOLUTION: A semiconductor laser device 100 comprises: a plurality of semiconductor laser elements 1a-1d arranged in steps; and a correction optical system and the like for correcting light beams La-Ld emitted from the respective semiconductor laser elements 1a-1d. The semiconductor laser elements 1a-1d are arranged at an inter-optical axis distance d1 in a straight line, and emit the plurality of light beams parallel to each other. The correction optical system includes Z-type folded mirrors 6b, 7b; 6c, 7c; 6d, 7d for reflecting the light beams Lb-Ld emitted from the semiconductor laser elements 1b-1d twice, reduces a difference among optical path lengths that the light beams Lb-Ld advance, and sets an inter-optical axis distance d2 of each optical beam Lb-Ld so as to be smaller than the inter-optical axis distance d1 while arranging optical axes of the respective light beams Lb-Ld in parallel.

Description

  The present invention relates to a semiconductor laser device that generates a high-power light beam using a plurality of semiconductor laser elements.

  In a conventional semiconductor laser device (for example, Patent Document 1), semiconductor laser elements are arranged on a step-like jig, and light emission points are two-dimensionally aggregated. In another prior art (for example, Patent Document 2), a so-called stack type semiconductor laser device in which the light emitting points are arranged on the same plane is used, there are many restrictions on cooling, and the light emitting point interval is set to be small. Although narrowing has been devised, no consideration is given to the optical path difference. In another prior art (for example, Patent Document 3), even in a configuration in which the optical axis is folded at a right angle and a step is provided, the optical path difference between the light emitting points is not taken into consideration.

Japanese Patent No. 3154181 (page 3, FIG. 1) Japanese Patent Laid-Open No. 2001-215443 (pages 3 to 5, FIG. 1) Japanese Patent Laid-Open No. 2001-44574 (pages 4 to 5, FIG. 5)

  In the conventional semiconductor laser device as described above, when considering the characteristics of the entire assembly of light emitting points, the influence of the optical path difference between each light beam is large, so that it is difficult to achieve high-convergence and high-efficiency oscillation of the laser light. Become. Also, when an external resonator is configured by arranging integrated optical elements for a plurality of light emitting points, the laser oscillation conditions change due to the optical path difference for each light emitting point, and the laser does not oscillate. There are problems such as a decrease in light convergence.

  An object of the present invention is to provide a semiconductor laser device capable of generating a light beam with high convergence and high efficiency.

In order to achieve the above object, a semiconductor laser device according to the present invention is a plurality of semiconductor laser elements arranged in a staircase pattern, and is arranged in a straight line with a distance d1 between the optical axes and is parallel to each other. A plurality of semiconductor laser elements emitting a beam;
For reducing the difference in the optical path lengths of the light beams emitted from the respective semiconductor laser elements and aligning the optical axes of the respective light beams in parallel while setting the distance d2 between the optical axes of the respective light beams to be smaller than d1. And a correction optical system.

The semiconductor laser device according to the present invention is a plurality of semiconductor laser elements arranged in a staircase pattern, wherein the distance between the optical axes is equal and a plurality of semiconductor laser elements emitting a plurality of light beams traveling in a plurality of directions are emitted. When,
And a correction optical system for reducing the difference in optical path lengths of the light beams emitted from the respective semiconductor laser elements and aligning the optical axes of the respective light beams in parallel.

  According to the present invention, it is possible to realize a plurality of light beams having a small difference in optical path length and a distance between optical axes and a good parallelism. As a result, a highly converged and highly efficient light beam can be generated.

It is a block diagram which shows Embodiment 1 of this invention. It is a block diagram which shows Embodiment 2 of this invention. It is a block diagram which shows Embodiment 3 of this invention. It is a block diagram which shows Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a semiconductor laser device according to Embodiment 1 of the present invention. The semiconductor laser device 100 includes a plurality (here, four examples) of semiconductor laser elements 1a to 1d, a support base 4 for supporting the semiconductor laser elements 1a to 1d, and light emitted from the semiconductor laser elements 1a to 1d. And a correction optical system for correcting the light beams La to Ld. Here, for easy understanding, the direction perpendicular to the paper surface is defined as the X direction, the traveling direction of the light beam emitted from the semiconductor laser element is defined as the Y direction, and the X direction and the direction perpendicular to the Y direction are defined as the Z direction.

  The support base 4 is formed of a metal material having excellent thermal conductivity, such as copper, and has a stepped shape including a horizontal plane having a horizontal pitch p along the X direction and a vertical plane having a vertical pitch d1 along the Y direction. Have On each horizontal surface of the support 4, plate-like heat sinks 3 a to 3 d having an equal thickness are fixed. The heat sinks 3a to 3d are made of, for example, copper and have a function of heat dissipation and electric conduction, but may be omitted when the support base 4 also uses these functions.

  The semiconductor laser elements 1a to 1d are fixed by soldering near the edges of the heat sinks 3a to 3d on the horizontal plane. Conductive wires (not shown) are connected to the upper surfaces of the semiconductor laser elements 1a to 1d. Each of the semiconductor laser elements 1a to 1d may be an LD (laser diode) chip having a single light emitting point, or may be an LD bar in which a plurality of light emitting points are linearly arranged.

  Optical elements 5a to 5d having a collimating function and a beam converting function are installed in front of the light emitting points of the semiconductor laser elements 1a to 1d, respectively. The optical elements 5a to 5d are constituted by a ball lens, a rod lens, a cylindrical lens, or the like, and are generally positioned so that the focal position of the lens coincides with the light emitting point.

  The light beam La emitted from the semiconductor laser element 1a located on the uppermost horizontal plane passes through the optical element 5a and is supplied to the outside as it is. The correction optical system includes Z-type folding mirrors 6b, 7b; 6c, 7c; 6d, 7d for reflecting the light beams Lb-Ld emitted from the semiconductor laser elements 1b-1d other than the semiconductor laser element 1a twice.

  The optical beam length of the light beam Lb emitted from the semiconductor laser element 1b located on the second horizontal plane is shortened by a distance equal to the horizontal pitch p and downward by a distance equal to the vertical pitch d1, with reference to the light beam La. is seperated. Therefore, the installation positions and reflection angles of the mirrors 6b and 7b are such that the difference in optical path length between the light beam La and the light beam Lb is as small as possible, the optical axes of the light beams La and Lb are aligned in parallel, and The distance d2 between the optical axes of the light beams La and Lb is adjusted to be smaller than d1.

  The light beam Lc emitted from the semiconductor laser device 1c located on the third horizontal plane is shortened by a distance equal to twice the horizontal pitch p with reference to the light beam La, and twice the vertical pitch d1. Is separated downward by a distance equal to Therefore, the installation positions and reflection angles of the mirrors 6c and 7c are such that the difference in optical path length between the light beam La and the light beam Lc is as small as possible, the optical axes of the light beams La and Lc are aligned in parallel, and The distance d2 between the optical axes of the adjacent light beams Lb and Lc is adjusted to be smaller than d1.

  The light beam Ld emitted from the semiconductor laser element 1d located on the fourth horizontal plane is shortened by a distance equal to three times the horizontal pitch p with reference to the light beam La, and is three times the vertical pitch d1. Is separated downward by a distance equal to Therefore, the installation positions and reflection angles of the mirrors 6d and 7d are such that the difference in optical path length between the light beam La and the light beam Ld is as small as possible, the optical axes of the light beams La and Ld are aligned in parallel, and The distance d2 between the optical axes of the adjacent light beams Lc and Ld is adjusted to be smaller than d1.

  As shown on the right side of FIG. 1, the light beams La to Ld are arranged vertically at equal intervals (beam pattern B1) at a distance d1 immediately after emission of the semiconductor laser element, but after passing through the correction optical system. It can be seen that they are arranged vertically at equal intervals (beam pattern B2) of distance d2 (<d1). Thus, a plurality of light beams having a small difference in optical path length and a distance between the optical axes and good parallelism can be realized. As a result, a highly converged and highly efficient light beam can be generated.

  Here, the case where four semiconductor laser elements 1a to 1d are used is illustrated, but it is also possible to use two, three, or five or more semiconductor laser elements.

  One or both of the Z-shaped folding mirrors 6b, 7b; 6c, 7c; 6d, 7d may be integrated with the optical elements 5a-5d, or attached to the heat sinks 3a-3d.

  The effect of this embodiment is that the optical path difference of all the light emitting points is reduced, so that the external resonator is configured by using the optical element as an integral unit for all the light emitting points, not individually. It is most effective. In addition, in the case of fiber coupling, it is difficult for deviation of the condensing point due to the optical path difference to occur, and as a result, a fiber coupling light source with high convergence can be obtained.

  In addition, as the number of light emitting points increases, the effect of the optical path difference between the arranged light emitting points increases, and thus the effect of the present embodiment is further exerted.

  Furthermore, compared with the case where a stack type apparatus in which a heat sink and a semiconductor laser element are stacked vertically is used, the present embodiment employs a step-like arrangement, so that the restriction on cooling can be greatly relaxed.

  In addition, since the distance between the optical axes can be changed using the correction optical system, the degree of freedom in mechanical design around the semiconductor laser element is increased, and laser light with higher convergence can be generated. .

Embodiment 2. FIG.
2 is a block diagram showing a semiconductor laser device according to a second embodiment of the present invention. FIG. 2 (a) is a plan view, FIG. 2 (b) is a front view, and FIG. 2 (c) is a right side view. . The semiconductor laser device 200 includes a plurality (eight examples here) of semiconductor laser elements 11a to 11h, a support base 14 for supporting the semiconductor laser elements 11a to 11h, and light emitted from the semiconductor laser elements 11a to 11h. And a correction optical system for correcting the light beams La to Lh. Here, for easy understanding, the direction perpendicular to the paper surface in FIG. 2B is the X direction, the final traveling direction of the light beam emitted by the semiconductor laser element is the Y direction, and the direction perpendicular to the X direction and the Y direction. Is the Z direction.

  The support base 14 is formed of a metal material having excellent thermal conductivity, such as copper, and as shown in FIG. 2B, the support base 14 has a horizontal plane having a horizontal pitch p along the X direction and a vertical direction along the Y direction. It has a staircase shape consisting of a vertical surface having a pitch d. On each horizontal surface of the support 4, plate-like heat sinks 13 a to 13 h are fixed. The heat sinks 13a to 13h are formed of, for example, copper and have functions of heat dissipation and electrical conduction, but may be omitted when the support base 14 also uses these functions.

  In the present embodiment, with respect to the heights of the light beams La to Lh, the level of the second horizontal plane Sb on which the semiconductor laser element 11b is positioned is a level difference d with reference to the height of the uppermost horizontal plane Sa on which the semiconductor laser element 11a is positioned. The third horizontal plane Sc where the semiconductor laser element 11c is located is lower by the level difference d, and the fourth horizontal plane Sd where the semiconductor laser element 11d is located is lower by the level d × 3/2. The fifth horizontal plane Se where 11e is located is lower by a step d × 2, and the sixth horizontal plane Sf where the semiconductor laser element 11f is located is lower by a step d × 5/2, and the seventh level where the semiconductor laser element 11g is located. The horizontal plane Sg of the eye is set to be lower by a step d × 3, and the eighth horizontal plane Sh where the semiconductor laser element 11h is located is set to be lower by a step d × 7/2.

  The semiconductor laser elements 11a to 11h are fixed by soldering near the edges of the heat sinks 13a to 13h on the horizontal plane. Conductive wires (not shown) are connected to the upper surfaces of the semiconductor laser elements 11a to 11h. Each of the semiconductor laser elements 11a to 11h may be an LD (laser diode) chip having a single light emitting point, or may be an LD bar in which a plurality of light emitting points are linearly arranged.

  Optical elements 15a to 15h having a collimating function and a beam converting function are installed in front of the light emitting points of the semiconductor laser elements 11a to 11h, respectively. The optical elements 15a to 15h are constituted by a ball lens, a rod lens, a cylindrical lens, or the like, and are generally positioned so that the focal position of the lens coincides with the light emitting point.

  The light beam La emitted from the semiconductor laser element 11a located on the uppermost horizontal plane Sa passes through the optical element 15a and is supplied to the outside as it is. The correction optical system includes folding mirrors 16b to 16h for reflecting the light beams Lb to Lh emitted from the semiconductor laser elements 11b to 11h other than the semiconductor laser element 11a at an angle of 90 degrees.

  The light beam Lb emitted from the semiconductor laser element 11b located on the second horizontal plane Sb travels in the + X direction, and is subsequently reflected by the folding mirror 16b at an angle of 90 degrees in the Y direction. At this time, the optical axis of the light beam Lb is aligned parallel to the light beam La, but is separated downward by a distance d / 2. Further, by setting the distance from the semiconductor laser element 11b to the mirror 16b to be equal to the distance from the semiconductor laser element 11a to the mirror 16b, the difference in optical path length between the light beam Lb and the light beam La is made as much as possible. Less.

  The light beam Lc emitted from the semiconductor laser element 11c located on the third horizontal surface Sc travels in the −X direction, which is opposite to the traveling direction of the light beam Lb, and then, an angle of 90 degrees in the Y direction by the folding mirror 16c. Reflect on. At this time, the optical axis of the light beam Lc is aligned parallel to the light beam La, but is separated downward by a distance d. Further, by setting the distance from the semiconductor laser element 11c to the mirror 16c to be equal to the distance from the semiconductor laser element 11a to the mirror 16c, the difference in optical path length between the light beam Lc and the light beam La is made as much as possible. Less.

  The light beam Ld emitted from the semiconductor laser element 11d located on the fourth horizontal plane Sd travels in the + X direction, and is subsequently reflected by the folding mirror 16d at an angle of 90 degrees in the Y direction. At this time, the optical axis of the light beam Ld is aligned in parallel to the light beam La, but is separated downward by a distance d × 3/2. Further, by setting the distance from the semiconductor laser element 11d to the mirror 16d to be equal to the distance from the semiconductor laser element 11a to the mirror 16d, the difference in optical path length between the light beam Ld and the light beam La is made as much as possible. Less.

  The light beam Le emitted from the semiconductor laser element 11e located on the fifth level horizontal plane Se travels in the −X direction, which is opposite to the traveling direction of the light beam Ld, and subsequently, an angle of 90 degrees in the Y direction by the folding mirror 16e. Reflect on. At this time, the optical axis of the light beam Le is aligned parallel to the light beam La, but is separated downward by a distance d × 2. Further, by setting the distance from the semiconductor laser element 11e to the mirror 16e to be equal to the distance from the semiconductor laser element 11a to the mirror 16e, the difference in optical path length between the light beam Le and the light beam La is made as much as possible. Less.

  The light beam Lf emitted from the semiconductor laser element 11f positioned on the sixth horizontal plane Sf travels in the + X direction, and is subsequently reflected by the folding mirror 16f at an angle of 90 degrees in the Y direction. At this time, the optical axis of the light beam Lf is aligned parallel to the light beam La, but is separated downward by a distance d × 5/2. Further, by setting the distance from the semiconductor laser element 11f to the mirror 16f to be equal to the distance from the semiconductor laser element 11a to the mirror 16f, the difference in optical path length between the light beam Lf and the light beam La is made as much as possible. Less.

  The light beam Lg emitted from the semiconductor laser element 11g located on the seventh horizontal plane Sg travels in the −X direction, which is opposite to the traveling direction of the light beam Lf, and then, an angle of 90 degrees in the Y direction by the folding mirror 16g. Reflect on. At this time, the optical axis of the light beam Lg is aligned parallel to the light beam La, but is separated downward by a distance d × 3. Further, by setting the distance from the semiconductor laser element 11g to the mirror 16g to be equal to the distance from the semiconductor laser element 11a to the mirror 16g, the difference in optical path length between the light beam Lg and the light beam La is made as much as possible. Less.

  The light beam Lh emitted from the semiconductor laser element 11h located on the eighth level horizontal plane Sh travels in the + X direction, and is subsequently reflected by the folding mirror 16h at an angle of 90 degrees in the Y direction. At this time, the optical axis of the light beam Lh is aligned parallel to the light beam La, but is separated downward by a distance d × 7/2. Further, by setting the distance from the semiconductor laser element 11h to the mirror 16h to be equal to the distance from the semiconductor laser element 11a to the mirror 16h, the difference in optical path length between the light beam Lh and the light beam La is made as much as possible. Less.

  As shown on the right side of FIG. 2C, it can be seen that the light beams La to Lh are arranged vertically at equal intervals (beam pattern B3) of a distance d / 2. Thus, a plurality of light beams having a small difference in optical path length and a distance between the optical axes and good parallelism can be realized. As a result, a highly converged and highly efficient light beam can be generated.

  For this reason, when optical beams emitted from a plurality of semiconductor laser elements are collectively coupled to a fiber, a focus point shift (aberration) caused by a difference in optical distance, a decrease in coupling efficiency, an incidence, an increase in emission NA, etc. Can be avoided. Further, when an external resonator is integrally formed with respect to a plurality of semiconductor laser elements, it is possible to reduce a decrease in efficiency and a decrease in light condensing performance due to an optical path difference.

  Furthermore, compared with the case where a stack type apparatus in which a heat sink and a semiconductor laser element are stacked vertically is used, the present embodiment employs a step-like arrangement, so that the restriction on cooling can be greatly relaxed.

  Although the case where eight semiconductor laser elements 11a to 11h are used is illustrated here, it is possible to use two to seven semiconductor laser elements or nine or more semiconductor laser elements. As the number of light emitting points increases, the effect of the optical path difference between the arranged light emitting points becomes larger, so the effect of the present embodiment is more exerted.

Embodiment 3 FIG.
3 is a block diagram showing a semiconductor laser device according to a third embodiment of the present invention. FIG. 3 (a) is a plan view and FIG. 3 (b) is a front view. In the present embodiment, in the semiconductor laser device 100 according to the first embodiment, the wavelength dispersion element 21 and the partial transmission mirror 22 are arranged as external resonators on the emission side of the correction optical system.

  The partial transmission mirror 22 has, for example, a characteristic of reflecting 90% of incident light and transmitting 10%, and constitutes an optical resonator in combination with the rear end faces of the semiconductor laser elements 1a to 1d. Functions as an output mirror of the optical resonator.

  The wavelength dispersion element 21 includes, for example, a diffraction grating (grating), a prism, and the like, and has a characteristic that the emission direction changes depending on the wavelength of the light beam. When the wavelength dispersion element 21 is disposed inside the optical resonator, the wavelength selectivity of the optical resonator is increased, and a single longitudinal mode oscillation can be realized. A configuration in which the wavelength dispersion element 21 is not disposed inside the optical resonator is also possible, and in this case, multiple longitudinal mode oscillations can be realized.

  By using such an external resonator, it is possible to generate laser light with high convergence. In addition, since the difference in the optical path lengths of the light beams La to Ld is reduced in the semiconductor laser device 100, laser light with higher convergence can be realized.

Embodiment 4 FIG.
4 is a block diagram showing a semiconductor laser device according to a fourth embodiment of the present invention. FIG. 4 (a) is a plan view and FIG. 4 (b) is a front view. In the present embodiment, in the semiconductor laser device 200 according to the second embodiment, the wavelength dispersion element 21 and the partial transmission mirror 22 are arranged as external resonators on the emission side of the correction optical system.

  The partial transmission mirror 22 has, for example, a characteristic of reflecting 90% of incident light and transmitting 10%, and constitutes an optical resonator in combination with the rear end faces of the semiconductor laser elements 1a to 1d. Functions as an output mirror of the optical resonator.

  The wavelength dispersion element 21 includes, for example, a diffraction grating (grating), a prism, and the like, and has a characteristic that the emission direction changes depending on the wavelength of the light beam. When the wavelength dispersion element 21 is disposed inside the optical resonator, the wavelength selectivity of the optical resonator is increased, and a single longitudinal mode oscillation can be realized. A configuration in which the wavelength dispersion element 21 is not disposed inside the optical resonator is also possible, and in this case, multiple longitudinal mode oscillations can be realized.

  By using such an external resonator, it is possible to generate laser light with high convergence. In addition, since the difference in the optical path length of each of the light beams La to Ld is reduced in the semiconductor laser device 200, a laser beam with higher convergence can be realized.

1a to 1d, 11a to 11h semiconductor laser elements,
3a-3d, 13a-13h heat sink, 4,14 support base,
5a-5d, 15a-15h optical elements,
6b-6d, 7b-7d, 16b-16h Folding mirror,
21 wavelength dispersion element, 22 partial transmission mirror,
100, 200 semiconductor laser device,
La to Lh light beam, Sa to Sh horizontal plane.

Claims (6)

A plurality of semiconductor laser elements arranged in a step-like manner, arranged in a straight line at an inter-optical axis distance d1, and emitting a plurality of light beams parallel to each other;
For reducing the difference in the optical path lengths of the light beams emitted from the respective semiconductor laser elements and aligning the optical axes of the respective light beams in parallel while setting the distance d2 between the optical axes of the respective light beams to be smaller than d1. And a correction optical system.   2. The semiconductor laser device according to claim 1, wherein the correction optical system includes a Z-type folding mirror for reflecting the light beam emitted from the semiconductor laser element twice. A plurality of semiconductor laser elements arranged in a staircase, the plurality of semiconductor laser elements emitting a plurality of light beams having equal optical axis distances and traveling in a plurality of directions;
A semiconductor laser device, comprising: a correction optical system for reducing a difference in optical path lengths traveled by light beams emitted from the respective semiconductor laser elements and aligning optical axes of the respective light beams in parallel.   4. The semiconductor laser device according to claim 3, wherein the correction optical system includes a folding mirror for aligning the optical axes of the light beams emitted in the opposite directions from the two semiconductor laser elements in parallel.   5. The semiconductor laser device according to claim 1, further comprising a partial transmission mirror as an external resonator on the exit side of the correction optical system.   6. The semiconductor laser device according to claim 5, further comprising a wavelength dispersion element between the correction optical system and the partial transmission mirror.

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