JPH06224520A - Semiconductor laser light source device - Google Patents

Abstract

PURPOSE:To obtain a synthesized luminous flux from a semiconductor laser light source device without lowering the laser light synthesizing efficiency of the device even when the polarizing direction of laser light is deviated from the horizontal direction against the joint surface of a chip. CONSTITUTION:The title light source device is constituted of a first and second semiconductor lasers 1 and 2, collimator lenses 3 and 4 respectively aligned with the optical axes of laser beams emitted from the lasers 1 and 2, lambda/2-plate 5 aligned with the optical axis of the laser beam from the laser 2, and polarization beam splitter 6 posited to the intersection of the laser beams from the lasers 1 and 2. The plane of polarization of the laser beam from the laser 2 is rotated by means of the plate 5 so that the planes of polarization of the laser beams made incident to the splitter 6 can intersect each other at right angles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser light source device, and more particularly to a semiconductor laser light source device in which light beams of two semiconductor lasers are superposed using a beam splitter.

[0002]

2. Description of the Related Art Usually, the light emitted from a semiconductor laser is linearly polarized light, and therefore, in order to superimpose the light from two semiconductor lasers without loss of light quantity, a polarizing prism having a multilayer film formed on a prism, a walllast. The use of a polarizing beam splitter such as a prism may be considered. When a polarization beam splitter is used, it is necessary to make light beams whose polarization directions are orthogonal to each other, so that these two semiconductor lasers are arranged so that their chip bonding surfaces are orthogonal to each other with respect to the polarization beam splitter. Must be placed at.

However, in general, a semiconductor laser has a large divergence angle in the lateral direction (direction perpendicular to the chip bonding surface) as compared with the divergence angle in the longitudinal direction of the light emitting surface (direction parallel to the chip bonding surface). The cross-sectional view of the light flux of the laser light is longer in the lateral direction than in the direction corresponding to the longitudinal direction of the light emitting surface, so that the light emitting surfaces of the two semiconductor lasers are orthogonal to each other with respect to the polarization beam splitter. When arranged, a combined beam in which two beams having a narrow cross section are orthogonal to each other in a cross shape is obtained. However, when such an orthogonal synthetic beam is processed by an anamorphic optical system, there is a problem that a circular spot light cannot be obtained even if a substantially circular spot light is required.

In order to solve this problem, the chip bonding surfaces of the semiconductor lasers are arranged in parallel with respect to the polarization beam splitter, and a polarization surface such as a half-wave plate is provided between one of the semiconductor lasers and the polarization beam splitter. There is known a semiconductor laser light source device in which a means for rotating by 90 degrees is arranged so that the light beams from the polarization beam splitters are superposed with the directions of the light emitting surfaces of the respective semiconductor lasers aligned with each other (Japanese Patent Publication No. 60-53857). Gazette).

[0005]

However, in the semiconductor laser, the polarization direction of the laser beam is not always parallel to the chip bonding surface depending on the material forming the semiconductor, and the deviation of about ± 20 degrees at the maximum is possible. May occur.
When such a semiconductor laser is applied to the device of Japanese Patent Publication No. 60-53857, the polarization direction of each laser beam incident on the polarization beam splitter is deviated from the horizontal or vertical direction with respect to the chip bonding surface. However, there is a problem in that the laser beams cannot be orthogonal to each other and the laser beam combining efficiency is reduced.

In view of the above circumstances, the present invention can obtain a combined light flux without lowering the combining efficiency of the laser light even when the polarization direction of the laser light is deviated from the horizontal direction with respect to the chip joint surface. It is an object of the present invention to provide a semiconductor laser light source device capable of achieving the above.

[0007]

A semiconductor laser light source device according to the present invention comprises two semiconductor lasers and a polarization beam splitter which superimposes laser beams emitted from the respective semiconductor lasers and emits the laser beams. In a semiconductor laser light source device in which a laser is arranged so as to match the longitudinal directions of the cross-sectional shapes of the respective laser lights superposed by the polarization beam splitter, at least one of the semiconductor lasers and the polarized light A polarization plane rotating means for rotating the polarization plane of the laser light by a predetermined angle according to the polarization direction of the laser light emitted from each of the semiconductor lasers is arranged between the beam splitter and the beam splitter.

Another semiconductor laser light source device according to the present invention is the semiconductor laser light source device according to the above-mentioned present invention, wherein the polarization plane rotating means is rotatable about the optical axis of the laser light by λ / It is characterized by being two plates.

[0009]

In the semiconductor laser light source device according to the present invention, the polarization plane of the laser light is provided between at least one of the two semiconductor lasers and the polarization beam splitter depending on the polarization direction of the laser light emitted from each semiconductor laser. Since the polarization plane rotating means for rotating the laser beam by a predetermined angle is arranged, even if the polarization direction of the laser light with respect to the chip bonding surface differs depending on the semiconductor laser, the polarization plane of each laser light incident on the polarization beam splitter is changed. Rotate it
The polarization planes of the respective laser lights incident on the polarization beam splitter can be made substantially orthogonal to each other, and a combined light flux can be obtained without reducing the combining efficiency of the laser lights.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing the optical arrangement of a semiconductor laser light source device according to the first embodiment of the present invention. As shown in FIG. 1, a semiconductor laser light source device according to a first embodiment of the present invention includes a first semiconductor laser 1 and a second semiconductor laser 2.
And collimator lenses 3 and 4 arranged so as to pass through the optical axis of the laser light emitted from each of the semiconductor lasers 1 and 2, and on the optical axis of the laser light emitted from the second semiconductor laser 2. It comprises a λ / 2 plate 5 and a polarization beam splitter 6 arranged at the intersection of the laser light emitted from the first semiconductor laser 1 and the laser light emitted from the second semiconductor laser 2. is there.

The collimator lenses 3 and 4 are rotationally symmetric lenses if the semiconductor lasers 1 and 2 can ignore the difference in the origin of divergence in the orthogonal direction, and are in the orthogonal direction if the difference in the origin of divergence cannot be ignored. It is desirable that the lenses have different focal lengths.

The semiconductor lasers 1 and 2 have a wavelength of 68
It emits a laser beam of 0 nm, and the material of the chips constituting these semiconductor lasers 1 and 2 is Ga, Al,
Examples of semiconductors include As (arsenic) and P. A laser beam emitted from a semiconductor laser using such a semiconductor does not always have a plane of polarization parallel to the chip bonding surface of the semiconductor, and a deviation of up to about ± 20 degrees may occur. Therefore, in the present embodiment, the polarization direction of the polarization plane of the laser light emitted from the first semiconductor laser is 0 degree with respect to the chip bonding surface (parallel to the chip bonding surface), It is assumed that the polarization plane of the emitted laser light is rotated +10 degrees (clockwise is positive) with respect to the chip joint surface. Further, the λ / 2 plate 5 is rotated by a predetermined angle θ so that the polarization plane rotation angle of the λ / 2 plate 5 becomes 80 degrees.
Make _one rotation.

As described above, even when the semiconductor laser 2 whose polarization plane of the laser light is not parallel to the chip bonding surface is used, the polarization plane rotation angle of the λ / 2 plate 5 is set to the polarization plane of the laser light. By setting the angle θ ₁ according to the polarization direction,
Since the polarization planes of the laser lights emitted from the two semiconductor lasers 1 and 2 and incident on the polarization beam splitter 6 are orthogonal to each other, the combining efficiency of the laser lights can be maximized.

On the other hand, a laser beam polarization beam splitter 6
Assuming that the device in the present embodiment can be used when the transmission loss in 3 is less than 3%, the polarization plane of the laser light of the first semiconductor laser 1 is −10 to +10 with respect to the chip bonding surface. The second semiconductor laser 2 can be used in which the polarization plane of the laser light is rotated by 0 to +20 degrees with respect to the chip bonding surface.
As described above, in this embodiment, a semiconductor laser in which the polarization plane of the laser light is rotated by −10 to +20 degrees with respect to the chip bonding surface can be used, and it is described in Japanese Patent Publication No. 60-53857. Considering that only the laser whose polarization plane is rotated by -10 to +10 degrees with respect to the chip bonding surface can be used in the device, it is possible to improve the yield of the semiconductor laser and reduce the cost of the device. Can be measured.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a view showing the optical arrangement of a semiconductor laser light source device according to the second embodiment of the present invention. As shown in FIG. 2, the semiconductor laser light source device according to the second embodiment of the present invention includes a first semiconductor laser 11 and a second semiconductor laser 12.
And the collimator lenses 13 and 14 arranged so as to pass through the optical axes of the laser beams emitted from the respective semiconductor lasers 11 and 12, and the optical axes of the laser beams emitted from the first semiconductor lasers 11. a λ / 2 plate 15 and a λ / 2 plate 16 arranged on the optical axis of the laser light emitted from the second semiconductor laser 12,
The polarization beam splitter 17 is arranged at the intersection of the laser light emitted from the first semiconductor laser 11 and the laser light emitted from the second semiconductor laser 12.

Here, the semiconductor lasers 11 and 12 are made of semiconductors such as Ga, Al, As (arsenic), and P as in the first embodiment of the present invention described above, and emit laser light having a wavelength of 680 nm. It is something that is emitted. In addition, semiconductor lasers 11 and 12
The polarization plane of the laser light emitted from each semiconductor laser 11,
It is offset by a predetermined angle with respect to the 12 chip bonding surfaces. Therefore, in this embodiment, the polarization plane of the laser light emitted from the first semiconductor laser is −10 degrees (clockwise is positive) with respect to the chip bonding surface, and the laser light emitted from the second semiconductor laser is It is assumed that the polarization plane of is rotated by +10 degrees with respect to the chip joint surface. Also, λ / 2 plate
The polarization rotation angle of 15 is 10 degrees, and the polarization rotation angle of λ / 2 plate 16 is
Rotate by the specified angles θ ₂ and θ ₃ so that the angle becomes 80 degrees.

As described above, even when the semiconductor lasers 11 and 12 whose polarization planes of the laser light are not parallel to the chip joint surface are used, the polarization plane rotation angles of the λ / 2 plates 15 and 16 are set to the laser light. By setting the angles θ ₂ and θ ₃ according to the polarization plane of, the polarization planes of the laser beams emitted from the two semiconductor lasers 11 and 12 and incident on the polarization beam splitter 17 become orthogonal to each other. It is possible to maximize the laser light synthesis efficiency.

On the other hand, a laser beam polarization beam splitter 17
Assuming that the transmission loss in 3 is less than 3% in the usable state of this embodiment, the polarization plane of the laser beam of the first semiconductor laser 11 is −20 to + with respect to the chip bonding surface.
The second semiconductor laser that can be used is one that rotates 0 degrees.
As 12, a laser beam whose polarization plane is rotated by 0 to +20 degrees with respect to the chip bonding surface can be used. As described above, in this embodiment, a semiconductor laser in which the polarization plane of the laser light is rotated by -20 to +20 degrees with respect to the chip bonding surface can be used. In the device, the polarization plane is -10 to + relative to the chip joint surface.
Considering that only those rotated by 10 degrees can be used, the yield of the semiconductor laser can be improved and the cost of the device can be reduced, as in the above-described embodiments of the present invention.

In the above embodiment, the λ / 2 plate is used as a means for rotating the polarization plane of the laser light emitted from the semiconductor laser according to the polarization direction. However, this λ / 2 plate is used as the laser light. It may be rotatable about the optical axis of. For example, as shown in FIG. 3, the λ / 2 plates 15 and 16 of the semiconductor laser light source device according to the second embodiment of the present invention are rotatable in the arrow direction, and the laser beam emitted from the polarization beam splitter 17 is further changed. The light amount monitor means 20 for monitoring the light amount is provided, and the λ / 2 plates 15 and 16 are rotated so that the light amount of the laser light monitored by the light amount monitor means 20 becomes maximum. Thereby, even when the semiconductor laser in the semiconductor laser light source device is replaced, by rotating the λ / 2 plate according to the inclination of the polarization plane of the laser light emitted from the replaced semiconductor laser,
The polarization planes of the laser beams emitted from the respective semiconductor lasers can be configured to be orthogonal to each other, and a combined light flux can be obtained without lowering the beam combining efficiency.

Further, in the above embodiment, the λ / 2 plate is arranged behind the collimator lens.
The present invention is not limited to this, and it may be arranged so as to be in contact with the semiconductor laser and the collimator lens or with the emitting end face of the semiconductor laser.

[0023]

As described above in detail, in the semiconductor laser light source device according to the present invention, the polarization directions of the laser beams emitted from the two semiconductor lasers deviate from the direction horizontal to the chip bonding surface of the semiconductor laser. Even if it is, since the planes of polarization of the laser beams incident on the polarization beam splitter can be made orthogonal to each other, the beam combining efficiency can be maximized and the yield of the semiconductor laser light source device can be improved. It is possible to reduce the cost of the device.

[Brief description of drawings]

FIG. 1 is a diagram showing a semiconductor laser light source device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a semiconductor laser light source device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a semiconductor laser light source device in which a λ / 2 plate is rotatable in a second embodiment of the present invention.

[Explanation of symbols]

 1, 2, 11, 12 Semiconductor laser 3, 4, 13, 14 Collimator lens 5, 14, 15 λ / 2 plate 6, 17 Polarizing beam splitter

Claims (2)

[Claims] 1. A semiconductor device comprising: two semiconductor lasers; and a polarization beam splitter that superimposes laser beams emitted from the respective semiconductor lasers and emits the laser light, wherein the respective semiconductor lasers are superposed by the polarization beam splitters. In a semiconductor laser light source device arranged so as to match the longitudinal direction of the cross-sectional shape of each laser light, a polarization plane of the laser light is provided between at least one of the semiconductor lasers and the polarization beam splitter. A semiconductor laser light source device, characterized in that polarization plane rotating means for rotating a predetermined angle according to a polarization direction of the laser light emitted from each of the semiconductor lasers is provided. 2. The semiconductor laser light source device according to claim 1, wherein the polarization plane rotating means is a λ / 2 plate rotatable around an optical axis of the laser light.