WO2008047608A1

WO2008047608A1 - Semiconductor laser device

Info

Publication number: WO2008047608A1
Application number: PCT/JP2007/069448
Authority: WO
Inventors: Hirofumi Miyajima; Hirofumi Kan; Kazunori Kuroyanagi; Takayuki Uchiyama
Original assignee: Hamamatsu Photonics K.K.
Priority date: 2006-10-19
Filing date: 2007-10-04
Publication date: 2008-04-24
Also published as: JP5165226B2; JP2008103564A

Abstract

A semiconductor laser device comprising at least two semiconductor laser modules (30), a collimate lens (55) for collimating a laser light outputted from the semiconductor laser modules (30) in the fast direction, an optical element for transmitting a laser light outputted from at least one semiconductor laser module (30) out of laser lights from the collimate lens (55) and reflecting a laser light outputted from at least one other semiconductor laser module (30), thereby combining the laser lights, and a housing (20) for internally arranging the semiconductor laser modules, the collimate lens and the optical element. In this semiconductor laser device, the inner wall face (21) of the housing (20) facing the semiconductor laser modules (30) through the optical element is inclined at least in the fast direction.

Description

Specification

Semiconductor laser device

Technical field

The present invention relates to a high-power semiconductor laser device that collects laser light and emits it with a high energy density.

Background art

[0002] Semiconductor laser devices have been widely used in recent years for light sources for various purposes because of their ability to emit laser light at a high energy density despite their small size. At the same time, developments have been made to further increase the output of semiconductor laser devices. For example, in FIGS. 11 and 12 of Patent Document 1, laser light from one light source is transmitted through a laser light path from a plurality of semiconductor laser light sources substantially orthogonal to each other and lasers from other laser light sources are transmitted. A technology that increases the energy density by combining each laser beam from multiple semiconductor laser sources by disposing an optical element that reflects light at approximately 45 degrees with respect to each optical path has been disclosed. .

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-258624

Disclosure of the invention

Problems to be solved by the invention

By the way, when laser light is used for metal processing such as laser welding or laser cutting of a metal steel plate, a high energy density is particularly required. Therefore, it is conceivable to arrange a plurality of high-power semiconductor laser modules having a large number of active layers for generating laser light, as described in Patent Document 1, and to synthesize these laser lights by optical elements. The However, it is not always possible to combine all the generated laser beams and emit them to the outside. A part of the laser light to be reflected by the optical element may pass through the optical element and irradiate the inner wall surface of the housing. Since this laser beam is collimated in the thickness direction (fast direction) of the active layer in advance, it is reflected on the inner wall surface of the housing and returns to the active layer of the semiconductor laser module as it is to be activated. It will degrade the layer.

[0004] The present invention has been made to solve the above-described problems, and includes a plurality of semiconductor laser modules. In a semiconductor laser device having a module, laser light output from the semiconductor laser module is transmitted through the optical element and reflected by the inner wall surface of the housing, and is prevented from returning to the semiconductor laser module and degrading the active layer. An object of the present invention is to provide a semiconductor laser device that can be used.

Means for solving the problem

In order to achieve such an object, a semiconductor laser device of the present invention includes at least two or more semiconductor laser modules, a collimating lens that collimates laser light output from the semiconductor laser module in the fast direction, and Both laser beams are transmitted by transmitting laser light output from at least one semiconductor laser module and reflecting laser light output from at least one other semiconductor laser module. An optical element that synthesizes light, and a housing in which a semiconductor laser module, a collimator lens, and an optical element are disposed, and the inner wall surface of the housing that faces the semiconductor laser module through the optical element is at least in the fast direction It is inclined to.

[0006] According to this apparatus, laser light output from two or more high-power semiconductor laser modules having a large number of active layers for generating laser light is collimated in the fast direction by a collimating lens and synthesized by an optical element. Is done. At that time, some of the laser light that is reflected by the optical element and is to be combined with the laser light from other semiconductor laser modules is transmitted through the optical element, and the housing The inner wall may be irradiated. Even in this case, since the irradiated inner wall surface is inclined in the fast direction, the laser beam does not return to the emitted route and deteriorate the active layer of the semiconductor laser module.

[0007] When the inner wall surface of the housing is blackened, the scattering and absorption of the laser light applied to the inner wall surface of the housing is promoted, and therefore the laser beam returning to the semiconductor laser module is further increased. The laser light can be reduced, and the laser beam reflected by the inner wall surface of the casing is not irradiated to a certain location in the casing as a collective laser beam.

[0008] In addition, the inner wall surface of the casing irradiated with the laser beam may become a high temperature of several hundred degrees in some cases, thereby increasing the temperature inside the casing and deteriorating the components and resin installed therein. become. However, the semiconductor laser device has an inner wall that is irradiated with laser light from the housing. In the case of further including a cooling device provided in the housing wall at a location corresponding to the surface, it is possible to suppress an increase in temperature due to laser light irradiation.

The invention's effect

[0009] According to the present invention, of the laser light output from the semiconductor laser module, a part of the laser light to be reflected by the optical element is transmitted through the optical element and applied to the inner wall surface of the housing. However, it is possible to prevent the active layer from being deteriorated by being reflected by the inner wall surface and returning to the semiconductor laser module, and to provide a highly reliable semiconductor laser device.

Brief Description of Drawings

FIG. 1 is a conceptual diagram showing an example in which the semiconductor laser device 1 is used in a steel sheet welding line.

FIG. 2 is a perspective view in which the outer case of the semiconductor laser device 1 is partially broken.

3 is a perspective view showing a semiconductor laser module 30. FIG.

FIG. 4 is an explanatory diagram of a main part excluding the outer case 11 in the IV-IV cross section in FIG.

FIG. 5 is a cross-sectional view taken along the line V-V in FIG.

FIG. 6 is an explanatory diagram of the state of light emitted from the LD.

FIG. 7 is a view showing another form of the inclined surface of the inner wall surface of the housing 20.

Explanation of symbols

[0011] 1 · · Semiconductor laser device, 11 · · Outer case, 12 · · Cooling water inlet / outlet, 13 · · Power supply terminal, 20

• · Housing, 20a '· Cooling water passage cover, 21, 22, 23 · · Inclined surface of the inner wall of the housing, 24, 25

• · Cooling water passage, 30 · · Semiconductor laser module, 31 · 'LD array stack, 31A--LD array, 31Aa.' Active layer, 32 · electrode, 33 · flange, 40 · barrel, 51, 52 · 'Striped mirror, 53 · · Half-wave plate, 54 ·' Beam splitter, 55 · 'Collimate lens, 56 · · Collimate lens, 57 ·' Condenser lens.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of a semiconductor laser device according to the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted. FIG. 1 is a conceptual diagram showing an example in which the semiconductor laser device 1 of the present embodiment is applied to laser welding of a steel plate. Semiconductor The one-device apparatus 1 is slidably installed on the lower rail 2 by an appropriate holding member 3. The butted portions 4 of the steel plates S1 and S2 are welded by the laser beam condensed while moving along the butted portions 4 of the steel plates S1 and S2. The semiconductor laser device 1 is connected with a semiconductor laser module, a flexible pipe for circulating cooling water for cooling the housing wall, and a power cable for supplying power. The cooling water distribution pipe and the power cable are connected to a fixedly installed cooler and power source, respectively, and the end on the semiconductor laser device 1 side is connected to the upper rail 5 of the semiconductor laser device 1. It is arranged so that it can follow the movement!

FIG. 2 is a perspective view in which the outer case 11 of the semiconductor laser device 1 according to the present embodiment is partially broken. Inside the outer case 11, a casing 20 is installed with its front surface exposed to the outside. A lens barrel 40 for emitting laser light to the outside is attached to the front surface of the housing 20. In the outer case 11, four semiconductor laser modules 30-1 to 30-4 (only reference numeral 30 is used when the four are not distinguished) are attached to the casing 20. Further, the outer case 11 is provided with an external cooling water circulation pipe and a cooling water inlet / outlet 12 for connecting a pipe to a cooling portion of each semiconductor laser module 30 in the outer case 11. Also, on the bottom surface of the outer case 11, although not shown, a cooling water inlet / outlet for allowing the cooling water to flow through a cooling water passage formed in the housing wall described later is also provided. The outer case 11 is also provided with a power supply terminal 13 connected to an external power cable in order to supply power to each semiconductor laser module 30.

The casing 20 is formed of, for example, an aluminum alloy, and a black film of alumite (aluminum oxide formed by anodization) is formed on the inner surface of the casing 20 in order to prevent reflection of laser light as much as possible. It has been applied. Since the surface of the black film becomes an appropriate rough surface! /, It has the effect of dispersing the reflection of the laser light to some extent. An opening for attachment is formed in the housing 20, and a semiconductor laser module 30 — ;! ~ 30-4 is attached thereto.

FIG. 3 is a perspective view showing the semiconductor laser module 30 disposed in the opening of the housing 20. The semiconductor laser module 30 includes an LD array stack 31 in which a large number of semiconductor laser arrays (hereinafter referred to as “LD arrays”) 31A are stacked between electrodes 32 at both ends. It is attached and configured. Each LD array 31A forms a one-dimensional array of laser light emission points in which a plurality of active layers are arranged in a row in the horizontal direction in the drawing. The thickness direction of each active layer, that is, the stacking direction of the LD array 31A is referred to as the fast direction F, and the column direction of the active layers in the LD array 31A is referred to as the slow direction S. A cooling plate may be inserted between these LD arrays 31A. A connection terminal to the electrode 32 is provided on the opposite surface of the flange 33. Here, the semiconductor laser module 30 includes the power of the LD array stack 31 so that the output obtained by combining the laser light of a predetermined number of semiconductor laser modules 30 can be used for applications such as metal processing. It can be an LD stack or an LD array. Each semiconductor laser module 30 is attached to the opening so that the surface opposite to the mounting surface of the LD array stack 31 of the flange 33 closes the opening of the housing 20 and forms a part of the outer wall of the housing 20.

[0016] FIG. 4 is an explanatory diagram of a main part excluding the outer case 11 in the IV-IV cross section in FIG. That is, a longitudinal section of the housing 20 and the lens barrel 40 is shown. In FIG. 4, each of the LD array stacks 31 illustrated in FIG. 3 is positioned on the inner surface side of the housing 20 in a state where the semiconductor laser modules 30— ;! to 30-4 are attached. Also, the LD array 31A is stacked along the direction perpendicular to the paper surface of FIG. 4, and this direction is the fast direction of the semiconductor laser module 30. 5 is a cross-sectional view taken along the line VV in FIG. In this figure, the optical path of the laser light L1 of one semiconductor laser module 30-1 among the four semiconductor laser modules 30 is illustrated.

Here, the state of the laser light emitted from the LD array 31A of each semiconductor laser module 30 will be described. As shown in FIG. 6, the laser light L emitted from the active layer 31Aa has a fast direction F As shown by / 3, it has a large spread of about 30 to 40 degrees, and in the slow direction S is a small spread of about 8 to 10 degrees as shown by α. Therefore, collimating lenses 55— ;! to 55-4 for collimating the laser beam in the fast direction are arranged on the emission surface of each LD array 31A of each semiconductor laser module 30 as shown in FIGS.

[0018] As shown in FIG. 4, the semiconductor laser module 30-1 and the semiconductor laser module 30-2 are substantially perpendicular to each other, and are approximately 45 degrees to the optical axis of the laser beam emitted from them. The stripe mirror 51 is installed in the housing 20 with a holder at an angle. The The triple mirror 51 includes stripe-shaped mirrors stacked at the same pitch as the stacking pitch of the LD arrays 31A in the semiconductor laser modules 30-1 and 30-2. On the other hand, the LD arrays 31A in the semiconductor laser modules 30-1 and 30-2 are stacked with their positions shifted from each other by the same pitch as the striped mirror in the fast direction. Therefore, the laser beam emitted from each LD array 31A of the semiconductor laser module 30-2 and collimated in the fast direction by the collimating lens 55-2 is irradiated and reflected on each stripe-shaped mirror portion of the stripe mirror 51. Change the direction about 90 degrees. On the other hand, the laser beam emitted from each LD array 31A of the semiconductor laser module 30-1 and collimated in the fast direction by the collimating lens 55-1 is reflected between the striped mirrors 51 in the stripe mirror 51. Go straight through the part where is not formed. As a result, the laser light power from the semiconductor laser modules 30-1 and 30 ^{2 is} combined by the stripe mirror 51 and is incident on the half-wave plate 53. The half-wave plate rotates the polarization direction of the synthesized laser beam by 90 degrees.

The semiconductor laser modules 30-3 and 30-4 are also in the same relationship as described for the semiconductor laser modules 30 1 and 30-2, and the laser beams from them are combined by the stripe mirror 52 and are combined into a beam splitter. Incident at 54. Of the laser light, the beam splitter 54 transmits one of the P-polarized component and the S-polarized component and reflects the other. Therefore, the laser light emitted from the semiconductor laser modules 30-3 and 30-4 and synthesized by the stripe mirror 52 passes through the beam splitter 54 and travels straight. On the other hand, the laser beam emitted from the semiconductor laser modules 30-1 and 30-2 and synthesized by the stripe mirror 51 and whose polarization direction is changed by 90 degrees by the half-wave plate 53 is reflected by the beam splitter 54. . As a result, both laser beams are combined. A collimating lens 56 and a condensing lens 57 are arranged in the optical path inside the lens barrel 40 of the synthesized laser light, and the laser light from the four semiconductor laser modules 30—;! To 30—4 is received. The combined laser beam can be emitted for processing. Here, the stripe mirrors 51 and 52 may be slit mirrors having the same function, or between the laser diode modules 30-1 and 30-2 and between the semiconductor laser modules 30-3 and 30-4. The wavelength of the light is different, the laser light of a specific wavelength is transmitted, and the other specific wave Anti-long laser light ^] ,. Similarly, for the beam splitter 54, the wavelength of the synthesized laser light of the semiconductor laser modules 30-1 and 302 and the synthesized laser light of 30-3 and 30-4 are different without installing a 1Z2 wavelength plate. Leave

In the present embodiment, the entire inner wall surface of the housing 20 or at least the inner wall surface force S at a location facing the semiconductor laser module 30 installed, and the semiconductor laser module 30 are inclined in the fast direction. Yes. As shown in FIG. 5, as an example, the semiconductor laser module 30-1 has an inner wall 21 force that faces the laser splitter 54 and a stripe mirror 51 as an optical element for combining laser beams. It is slanted in the fast direction because it has many triangular irregularities extending in the slow direction. Similarly, the inner wall surface 22 facing the semiconductor laser module 30-2 in FIG. 4 is also inclined. The same applies to the inner wall surface 23 facing the semiconductor laser module 30-4.

[0021] In addition, cooling water passages 24 and 25 for circulating cooling water are formed in the walls corresponding to these inner wall surfaces. In Fig. 4, the force S formed only at two locations of the inner wall surfaces 21, 23 of the corresponding inner wall surfaces 21, 22, 23, may be formed in the walls corresponding to all the inner wall surfaces. You may form only in the wall of the inner wall surface 21 with which a big temperature rise is anticipated. The same applies to the inclination of the inner wall surface, and it may be formed only on the inner wall surface 21 where laser light irradiation due to leakage is particularly large. As shown in FIG. 5, the ends of the cooling water passages 24 and 25 are closed by the cooling water passage cover 20a so that the cooling water does not leak outside. Although not shown, the cooling water passages 24 and 25 have a connection hole with a cooling water inlet / outlet connected to the cooling device via a flexible pipe, so that the cooling water is connected to the cooling device. It is recirculated at.

Next, the operation of the semiconductor laser device 1 of the present embodiment will be described mainly with reference to FIG. The laser light L1 emitted from each LD array 31A of the semiconductor laser module 30-1 and collimated in the fast direction by the collimating lens 55-1 is similarly collimated by the stripe mirror 51 by the collimating lens 55-2. Synthesized with laser light from laser module 30-2. Next, the wavelength polarization direction is changed by 90 degrees by the half-wave plate 53, reflected by the beam splitter 54, and the traveling direction is changed by 90 degrees. Together with the laser light from the joules 30-3 and 30-4, the light is condensed by the condenser lens 57 and emitted to the outside.

However, the force is all the laser light force incident on the beam splitter 54, for example, an S polarization component, and is not necessarily reflected by the beam splitter 54 in the emission direction. In some cases, a P-polarized component or the like may be mixed, and a part of the laser light passes through the beam splitter 54 and is irradiated on the inner wall surface 21 of the housing 20. In the arrangement as shown in FIG. 4, the partial power S of the combined laser light of the semiconductor laser modules 30-3, 30-4 may be reflected by the beam splitter 54 and applied to the inner wall surface 21. obtain. Therefore, a part of the laser light goes straight to the inner wall surface 21 of the housing 20 as indicated by a broken line in FIG. Since the laser beam is collimated in the fast direction, if the inner wall surface 21 is a vertical surface (a surface along the fast direction) as usual, the laser beam reflected by the inner wall surface 21 is in the fast direction. For this, the path that came is returned straight and the active layer of each LD array 31A of the semiconductor laser module 30-1 is degraded. Here, in the present embodiment, as shown in FIG. 5, the inner wall surface 21 has an irregular shape with a triangular cross section and is a surface inclined in the fast direction, so that it is reflected at an inclination angle in the fast direction. As a result, it is possible to prevent returning to the LD array 31A. Here, the inclination angle is preferably 1 degree or more. Less than this tilt is not sufficient to function as a ramp and prevent the reflected light from returning to the LD array. Further, a sufficient inclination angle is preferably 5 degrees or more.

In the present embodiment, the inner wall surface of the aluminum alloy casing 20 including the inner wall surface 2;! To 23 is provided with an alumite black coating so as to absorb laser light as much as possible. Since the black coating is also roughened at the same time, the absorption is increased and the reflected light is scattered as much as possible. Although such a black coating cannot sufficiently prevent the reflected laser beam from returning to the LD array 31A, it absorbs as much as possible the reflection of the laser beam irradiated to the inclined inner wall surface. In addition, the action of the inclined surface is also supported for scattering of the reflected light. In place of the black film, it is also possible to use a copper plate that has been roughened with a chemical solution and blackened, and is adhered to the inner wall surface of the aluminum alloy casing 20.

[0025] The above is an example of FIG. 5 showing the path from the semiconductor laser module 30-1 to the inner wall surface 21. The same applies to the other points. For example, the laser beam emitted from the semiconductor laser module 30-2 and collimated in the fast direction by the collimator lens 55-2 is reflected by the stripe mirror 51. Instead, the laser beam that has been transmitted and traveled straight can prevent the return of the semiconductor laser module 30-2 to the LD array 31A because the inner wall surface 22 is inclined in the same manner as the inner wall surface 21 in FIG. . Here, the stripe mirror 51 (the same applies to the slit mirror) differs from the beam splitter 54 described in the example of FIG. 5 in that the reflection / transmission mechanism is different. Then it is transparent. Therefore, even if the laser beam power S from each LD array 31A of the semiconductor laser module 30-2 is aligned so that it is reflected by the mirror part of the stripe mirror 51, some of the error is caused by the error. The laser light is transmitted through the V, part where the mirror of the stripe mirror 51 does not exist.

Next, cooling of the housing 20 will be described. Since the semiconductor laser device 1 in the present embodiment is used for metal processing or the like, a high output such as 4 to 5 kW (kilowatt) may be required. Therefore, even if the proportion of laser light that should be reflected by the optical elements (stripe mirrors 51 and 52, beam splitter 54) is small, the inner wall surface 2 of the housing 20; The energy of the laser light irradiated to 23 is considerable. Moreover, when the inner wall surface is coated with a black film, energy absorption is also high, and the inner wall surface of the housing 20 may locally rise to a temperature of 300 ° C or higher. If the casing 20 is deformed due to such a temperature rise, the position of the semiconductor laser module 30 or each optical element installed there is distorted! /, And the optical path length of the laser light is changed. Cause trouble. In addition, since the ambient temperature in the housing 20 also rises, it causes deterioration of the adhesive and solder used to fix the components and the installed components themselves. In particular, the resin coating of the lead of the humidity sensor installed to monitor the humidity at the light emitting portion of the semiconductor laser module 30 is deteriorated.

Therefore, in the present embodiment, as clearly shown in FIG. 5, in particular, the cooling water passage 24 is provided in the wall of the housing 20 at a location corresponding to the inner wall surface 2;! , 25 is formed. The cooling water is introduced into the cooling water inlet on the bottom surface of the semiconductor laser device 1 by an external cooler power pipe, and circulates through the cooling water passages 24 and 25 by piping (not shown). Cool the body 20 walls. Thereafter, the cooling water is discharged from the cooling water outlet on the bottom surface of the semiconductor laser device 1 through a pipe (not shown) and returned to the cooler through the pipe.

[0028] As described above, in the present embodiment, the laser beam is emitted by a simple configuration in which an inclination is formed in the inner wall surface 2 of the casing 20 that receives irradiation due to leakage of laser light in the optical element; It is possible to prevent the active layer from deteriorating by returning to the LD array of the semiconductor laser module 30. Further, the inner wall surface 2;! To 23 is blackened and roughened by applying a black film or the like, so that the laser beam can be prevented from returning by the inclined surface. Furthermore, it is possible to suppress an increase in temperature due to irradiation with laser light by cooling with cooling water.

[0029] In the present embodiment, the inclination of the inner wall surface 2;! To 23 has a large number of triangular concave and convex shapes as shown in Fig. 5, so that the reflected laser light is divided almost evenly on both sides in the fast direction. Can be scattered. Even if the angle of inclination is increased to prevent the reflected laser light from returning to the LD array of the semiconductor laser module 30 more reliably (the triangle has a sharp shape with a long isosceles side) The space of the entire casing 20 does not become particularly large.

[0030] The inclination shape of the inner wall surface 2;! To 23 of the housing 20 in the present embodiment is not limited to this, and may be the shape shown in FIG. As shown in (A) and (B) of Fig. 7, if one inclined surface is inclined in either of the fast directions, manufacturing becomes easier. (C) When a small number of triangles are used as shown in (D), the reflected laser light can be distributed almost evenly on both sides in the fast direction, and space is not required so much. Easy. As shown in (E), when the concavo-convex shape has a large number of triangles and one side is elongated, it is almost the same as the embodiment of FIG. ) Can deflect the reflection much. (F) As shown in (G), the slopes of (A) and (B) can be combined with a number of triangular shapes shown in Fig. 5 or (E). Can be increased. In any case, the inclination angle with respect to the fast direction is preferably 1 degree or more, and more preferably 5 degrees or more, as in the case of FIG. The upper limit of the tilt angle can be determined depending on the tilt mode, taking into consideration that the space efficiency is not particularly deteriorated and the manufacturing efficiency.

[0031] In the present embodiment, the cooling device provided on the wall surface corresponding to the inner wall surface 2;! For example, the force used for the cooling water passages 24 and 25 may be electronic cooling using a Peltier element, a heat pipe, or the like. Needless to say, the object of use is not limited to metal processing such as laser welding or laser cutting, but can be applied to those requiring a high-power semiconductor laser device.

Claims

The scope of the claims

[1] at least two or more semiconductor laser modules;

A collimating lens for collimating the laser beam output from the semiconductor laser module in the fast direction;

By transmitting laser light output from at least one of the semiconductor laser modules and reflecting laser light output from at least one of the other semiconductor laser modules among the laser light from the collimating lens, An optical element that synthesizes the laser light;

A housing in which the semiconductor laser module, the collimating lens, and the optical element are disposed;

With

A semiconductor laser device, wherein an inner wall surface of the casing facing the semiconductor laser module through the optical element is inclined at least in the fast direction.

[2] The semiconductor laser device according to [1], wherein the inner wall surface of the housing is blackened.

[3] The semiconductor laser device according to [1] or [2], further comprising a cooling device provided in a housing wall at a location corresponding to the inner wall surface of the housing.