JPWO2020080220A1 - Laser light source device - Google Patents

Abstract

An object of the present invention is to provide a laser light source device that reduces the occurrence of interference fringes and speckles and reduces the temperature rise due to laser oscillation. The laser light source device includes a base, a plurality of semiconductor laser elements that are individually held by the base and emits a plurality of laser beams whose polarization directions are aligned in one direction, and a plurality of laser light beams in one direction. Includes a polarization converter that disturbs the alignment. The polarization conversion unit is separately arranged from the first polarization rotating element that is selectively arranged corresponding to the semiconductor laser element that emits a part of the laser light and converts the polarization of the part of the laser light into the left-handed circularly polarized light. A second polarized light rotating element, which is selectively arranged corresponding to another semiconductor laser element that emits a part of the laser light, and converts the polarized light of another part of the laser light into right-handed circularly polarized light. Including.

Description

The present invention relates to a laser light source device.

The semiconductor laser element emits a laser beam having low power consumption and excellent monochromaticity and high directivity. Semiconductor laser devices having such features are expected as a replacement light source for lamps that are currently in widespread use. For example, in recent years, semiconductor laser elements have been attracting attention as a light source for projection type display devices such as projectors. When a semiconductor laser element is mounted as a light source in a projection type display device, the semiconductor laser element has a small light emitting area, so that the optical element required for spatial synthesis of laser light can be miniaturized in its optical design. Further, the miniaturization of the optical element enables the miniaturization of the display device itself such as a digital mirror device (DMD (Digital Mirror Device)) and a liquid crystal display (LCD (Liquid Crystal Display)), and as a result, the system cost is reduced. To do.

With the current semiconductor laser device, it is difficult to achieve the output required for a projection type display device with one device. Therefore, in general, the light source of the projection type display device is composed of a plurality of semiconductor laser elements.

The laser light emitted from the semiconductor laser element is composed of waves having a uniform phase. This feature produces the monochromaticity and high directivity of semiconductor lasers. On the other hand, when a plurality of waves overlap, a striped pattern or speckle is generated due to the coherence of the waves. A speckle is a particulate pattern due to the coherence of random waves that appear due to the laser beam radiated onto the screen. Such an interference pattern has contributed to the deterioration of image quality when a laser is used as a light source of a projection type display device.

As a means for reducing interference fringes and speckles, a means for mixing semiconductor laser light of a plurality of wavelengths or a means for disturbing the uniformity of polarization of the semiconductor laser light is effective.

For example, Patent Document 1 describes a laser light source device that rotates the polarization of laser light emitted from one or more light emitting points of a laser light source by 90 ° by a polarization rotating portion arranged on the optical axis thereof. Has been proposed. The laser light source device is an array type laser light source in which a plurality of laser beams oscillate from one semiconductor laser chip.

Japanese Unexamined Patent Publication No. 2011-242573

As described above, the laser beam tends to generate interference fringes and speckles due to its coherence. Although the laser light source device of Patent Document 1 can reduce interference fringes and speckles, since it is an array type laser light source, the gain is reduced due to the temperature rise due to the heat generated from the adjacent laser, and the output is sufficient. Cannot be obtained.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a laser light source device capable of reducing the occurrence of interference fringes and speckles and reducing the temperature rise due to laser oscillation. To do.

The laser light source device according to the present invention includes a base, a plurality of semiconductor laser elements each individually held on the upper surface of the base, and emitting a plurality of laser beams having the same polarization direction in one direction, and a plurality of laser beams. Among them, a polarization conversion unit that disturbs the polarization directions of a plurality of laser beams so that they are not aligned in one direction by rotating the polarization directions of at least a part of the laser beams is included. The polarization conversion unit includes a plurality of polarization rotating elements that convert the polarization of a plurality of laser beams into circular polarization. The plurality of polarized light rotating elements are selectively arranged corresponding to the semiconductor laser element that emits a part of the laser light among the plurality of semiconductor laser elements, and the polarized light of the part of the laser light is converted into the circularly polarized light that rotates counterclockwise. The first polarized light rotating element and another semiconductor laser element that emits another part of the laser light among the plurality of semiconductor laser elements are selectively arranged to polarize the other part of the laser light. Includes a second polarized rotating element that converts to right-handed circularly polarized light.

According to the present invention, it is possible to provide a laser light source device that reduces the occurrence of interference fringes and speckles and reduces the temperature rise due to laser oscillation.

Objectives, features, aspects, and advantages of the present invention will become more apparent with the following detailed description and accompanying drawings.

It is a perspective view which shows the structure of the laser light source apparatus in Embodiment 1, and the laser light emitted from the laser light source apparatus. It is an exploded perspective view which shows the structure of the laser light source apparatus in Embodiment 1. FIG. It is a figure which shows the structure of the polarization rotating element in Embodiment 1. FIG. It is a figure which shows the structure of the polarization rotating element in Embodiment 1. FIG. It is a perspective view which shows the detailed structure of the semiconductor laser element in Embodiment 1. FIG. It is a perspective view which shows the structure of the base and the semiconductor laser element in Embodiment 1. FIG. It is sectional drawing in AA'shown in FIG. It is a figure explaining the operation of the polarization rotating element in Embodiment 1. FIG. It is a figure explaining the operation of the polarization rotating element in Embodiment 1. FIG. It is a figure explaining the operation of the polarization rotating element in Embodiment 1. FIG. It is a figure explaining the operation of the polarization rotating element in Embodiment 1. FIG. It is a perspective view which shows the structure of the spacer and the lens in Embodiment 1. FIG. It is sectional drawing in BB'shown in FIG. It is a figure which shows the structure of the spacer and the polarization rotating element of the laser light source apparatus in the modification 1 of Embodiment 1. FIG. It is a figure which shows the polarization element substrate which includes the polarization rotation element in the modification 1 of Embodiment 1. It is a figure which shows the structure of the spacer of the laser light source apparatus, and the polarization rotating element in the modification 2 of embodiment. It is a figure which shows the polarization element substrate which includes the polarization rotation element in the modification 2 of Embodiment 1. FIG. It is a perspective view which shows the structure of the laser light source apparatus in Embodiment 2 and the laser light emitted from the laser light source apparatus. It is an exploded perspective view which shows the structure of the laser light source apparatus in Embodiment 2. It is a perspective view which shows the structure of the spacer and the polarization rotating element in Embodiment 2. FIG. FIG. 5 is a cross-sectional view taken along the line CC'shown in FIG. It is a figure which shows the structure of the spacer of the laser light source apparatus, and the polarization rotating element in the modification of Embodiment 2. It is a perspective view which shows the structure of the laser light source apparatus of Embodiment 3 and the laser light emitted from the laser light source apparatus. It is a figure which shows the structure of the spacer and the polarization rotating element in Embodiment 3. FIG. It is a perspective view which shows the structure of the laser light source apparatus in Embodiment 4, and the laser light emitted from the laser light source apparatus. It is an exploded perspective view which shows the structure of the laser light source apparatus in Embodiment 4.

<Embodiment 1>
The laser light source device according to the first embodiment will be described. FIG. 1 is a perspective view showing the configuration of the laser light source device 1 according to the first embodiment and the laser beams 71 to 74 emitted from the laser light source device 1. FIG. 2 is an exploded perspective view showing the configuration of the laser light source device 1.

The laser light source device 1 is composed of a base 30, semiconductor laser elements 101 to 104, lenses 41 to 44, a spacer 20, and a polarizing rotating element 51 to 54.

The base 30 supports the semiconductor laser elements 101 to 104 on the upper surface 30A. In the first embodiment, the base 30 has a flat surface on the upper surface 30A, and the semiconductor laser elements 101 to 104 are fixed to the flat surface. The base 30 is, for example, a flat plate.

The base 30 is provided with elongated holes 31 to 34. The elongated holes 31 to 34 are through holes here. The elongated holes 31 to 34 are holes into which the two lead pins 14 of the semiconductor laser elements 101 to 104 are inserted. A current is supplied to each semiconductor laser device via the lead pin 14. The x, y, and z axes shown in each figure constitute a Cartesian coordinate system. The x-axis and y-axis are parallel to the upper surface 30A of the base 30, and the z-axis points above the base 30.

The semiconductor laser elements 101 to 104 are elements on which a semiconductor laser chip that oscillates one laser beam is mounted. Each of the semiconductor laser elements 101 to 104 is individually held on the upper surface 30A of the base 30. Here, each semiconductor laser element is fixed to a plane formed on the upper surface 30A of the base 30. Each semiconductor laser element emits a laser beam upward with respect to the base 30. The semiconductor laser chip may be configured by dividing the oscillating unit into two to three in order to improve efficiency.

The semiconductor laser elements 101 to 104 emit laser beams 71 to 74 in which the respective polarization directions are aligned in one direction. In the first embodiment, the polarized light of the laser beams 71 to 74 emitted from the semiconductor laser element 101 to 104 is parallel in the y-axis direction (not shown). Further, the semiconductor laser elements 101 to 104 emit laser beams 71 to 74 having a wide cross-sectional shape in the x-axis direction in parallel with the z-axis direction.

The spacer 20 is provided so as to cover the upper part of the semiconductor laser element 101 to 104. The spacer 20 has a function of holding the lenses 41 to 44, which will be described later, and keeping the distance between each lens and each semiconductor laser element constant.

The spacer 20 has spacer windows 21 to 24 on the upper surface. In the first embodiment, the outer shape of the spacer window portions 21 to 24 has a square shape. Further, the spacer 20 has spacer step portions 25 to 28 provided on the outer periphery of each of the spacer window portions 21 to 24. A polarizing rotating element can be installed on each spacer step portion. The laser beams 71 to 74 emitted from the semiconductor laser elements 101 to 104 pass through the spacer window portions 21 to 24, respectively. That is, the spacer 20 includes a frame structure including spacer window portions 21 to 24 and spacer step portions 25 to 28 at positions where a plurality of laser beams 71 to 74 pass. Each frame structure holds each of the plurality of polarization rotating elements 51 to 54.

The spacer 20 may be fastened and fixed to the upper surface 30A of the base 30 with screws, or may be fixed with an adhesive. Alternatively, the spacer 20 may be fixed by both of them. The spacer 20 is manufactured by die-casting, for example, zinc or aluminum in consideration of moldability. However, since the spacer 20 is not required to have a thermal effect, the spacer 20 may be made of a resin material.

The polarization rotating elements 51 to 54 form a polarization conversion unit. The polarization conversion unit rotates the polarization directions of at least a part of the laser beams 71 to 74 and disturbs the polarization directions of the laser beams 71 to 74 so that they are not aligned in one direction.

The polarization rotating elements 51 and 53 convert the polarization directions of some of the laser beams 71 and 73 out of the laser beams 71 to 74 into counterclockwise circular polarizations 91 and 93. The polarization rotating elements 51 and 53 are selectively arranged corresponding to the semiconductor laser elements 101 and 103 that emit a part of the laser light 71 and 73 among the semiconductor laser elements 101 to 104.

Further, the polarized light rotating elements 52 and 54 convert the polarization direction of another part of the laser beams 71 to 74 of the laser beams 72 and 74 into right-handed circularly polarized light 92 and 94. The polarization rotating elements 52 and 54 are selectively arranged corresponding to the other semiconductor laser elements 102 and 104 that emit the laser light 72 and 74 of the other part of the semiconductor laser elements 101 to 104.

Here, the rotation direction of circularly polarized light is defined according to the right-handed screw rule. In other words, if the relationship between the traveling direction of light and the rotation matches the movement of the right-handed screw, it is defined as right-handed circular polarization, and if it matches the left-handed screw movement, it is defined as left-handed circular polarization. ing.

FIG. 3 is a diagram showing the configurations of the polarizing rotating elements 51 and 53. FIG. 4 is a diagram showing the configuration of the polarizing rotating elements 52 and 54. The polarizing rotating elements 51 to 54 have a fast axis (F axis) 50A in a direction having a low refractive index and a slow axis (S axis) 50B in a direction having a high refractive index. The polarization rotating elements 51 to 54 are plate-shaped elements having a plane parallel to the FS plane in which the fast axis (F axis) 50A and the slow axis (S axis) 50B are orthogonal to each other. Here, the polarizing rotating elements 51 to 54 are 1/4 wave plates. The 1/4 wavelength plate delays the components of the laser beam 71 to 74 in the fast axis direction by 1/4 wavelength in the slow axis direction.

The polarization rotating elements 51 and 53 are arranged so that the speed axis 50A is at an angle of 45 ° and the slow axis 50B is at an angle of −45 ° with respect to the polarization directions of the laser beams 71 and 73 emitted from the semiconductor laser elements 101 and 103. Will be done. The polarized light of the laser beams 71 and 73 emitted from the semiconductor laser elements 101 and 103 is linearly polarized light parallel to the y-axis. Therefore, the speed axis 50A forms an angle of 45 ° with respect to the y-axis, and the slow axis 50B forms an angle of −45 ° with respect to the y-axis (see FIGS. 2 and 3).

On the other hand, in the polarization rotating elements 52 and 54, the speed axis 50A forms an angle of −45 ° and the slow axis 50B forms an angle of 45 ° with respect to the polarization directions of the laser beams 72 and 74 emitted from the semiconductor laser elements 102 and 104. Arranged like this. Therefore, the fast axis 50A forms an angle of −45 ° with respect to the y-axis, and the slow axis 50B forms an angle of 45 ° with respect to the y-axis (see FIGS. 2 and 4).

As shown in FIG. 2, the outer shape of the polarizing rotating elements 51 to 54 has a square shape similar to the outer shape of the spacer step portions 25 to 28. The square consists of sides parallel to the x-axis or y-axis. The speed axis 50A and the slow axis 50B of the polarization rotating elements 51 to 54 coincide with each other in the diagonal direction of the square. The polarization rotating elements 51 to 54 are held by the spacer step portions 25 to 28, respectively. The polarization rotating elements 51 and 53 are selectively arranged corresponding to the semiconductor laser elements 101 and 103 by being housed in the spacer stepped portions 25 and 27. Further, the polarization rotating elements 52 and 54 are selectively arranged corresponding to the other semiconductor laser elements 102 and 104 by being housed in the spacer stepped portions 26 and 28.

In the first embodiment, the polarization rotating elements 51 to 54 are arranged on the upper surface side of the spacer 20, but the polarization rotating elements 51 to 54 may be arranged on the bottom surface side of the spacer 20. In that case, the polarizing rotating element is fixed to, for example, a spacer step portion provided on the back surface of the spacer 20 with an adhesive or a holding member.

The shape of the polarizing rotating element may be a rectangle, a circle, an ellipse, or the like other than a square, and may be a shape that covers the laser beams 71 to 74 of the semiconductor laser elements 101 to 104.

Lenses 41 to 44 focus the laser light 71 to 74. The laser beams 71 to 74 transmitted through the lenses 41 to 44 travel in directions parallel to the z-axis, respectively. The lenses 41 to 44 are held by the spacer 20. Further, the lenses 41 to 44 are arranged so as to cover the spacer window portions 21 to 24, respectively.

Next, the detailed configuration of the semiconductor laser device according to the first embodiment will be described.

FIG. 5 is a perspective view showing a detailed configuration of the semiconductor laser device 101. The semiconductor laser element 101 has a configuration in which a semiconductor laser chip is included in a TO-Can type package. The TO-Can type semiconductor laser element 101 is mainly composed of a cap 11, a glass window 12, a stem 13, a lead pin 14, and a semiconductor laser chip (not shown).

The cap 11 is provided on the upper part of the stem 13. The glass window 12 is provided on the upper surface of the cap 11. The lead pin 14 is provided at the lower part of the stem 13. The semiconductor laser chip is arranged inside the cap 11.

The semiconductor laser chip has a main optical axis in a direction perpendicular to the stem 13. That is, the semiconductor laser chip emits the laser beam 71 in the z-axis direction. In general, when moisture or dust in the air adheres to the end face of the semiconductor laser chip, the semiconductor laser chip is easily destroyed. However, in the TO-Can type package, the semiconductor laser chip is sealed by the cap 11. Therefore, the airtightness inside the cap 11 is maintained, and the conditions required for the driving environment of the semiconductor laser chip are relaxed. Further, the TO-Can type package element is small. Therefore, it is easy to adjust the number of units used, that is, to scale the optical output according to the required specifications.

A high-power end-face emission type laser chip is used as the light source of the projection type display device. The main material of the semiconductor laser chip is a compound semiconductor such as GaAs or GaN. The active layer of the semiconductor laser chip is formed by epitaxial growth. In the first embodiment, the direction of epitaxial growth corresponds to the x-axis direction, and the horizontal direction of the active layer corresponds to the y-axis direction. The laser beam 71 is emitted from the chip end face located in the direction (z-axis direction) orthogonal to the epitaxial growth direction (x-axis direction). The laser beam 71 is emitted from an emission spot of about 1 μm in the vertical direction (x-axis direction) of the active layer and several tens to several hundreds μm in the horizontal direction (y-axis direction) of the active layer on the end face of the chip. Since the exit port of the active layer in the vertical direction (x-axis direction) is very small, the laser beam 71 spreads in the x-axis direction due to the diffraction effect. The spread of the laser beam in the x-axis direction is about 60 ° in full angle. The spread of the laser beam in the vertical direction (x-axis direction) of the active layer is about 10 times larger than the spread of the laser beam in the horizontal direction (y-axis direction) of the active layer. Therefore, the cross section of the laser beam 71, that is, the far-field image, has an elliptical shape as shown in FIG.

Further, generally, in a semiconductor laser device of a TO-Can package, the arrangement direction of the two lead pins 14 is the same as the horizontal direction (y-axis direction) of the active layer of the semiconductor laser chip. Therefore, the laser beam 71 has a small spread in the arrangement direction of the lead pins 14, and a large spread in the x-axis direction orthogonal to the spread.

The polarization of the laser beam 71 emitted from the semiconductor laser device 101 having the above configuration is parallel to the direction horizontal to the active layer (y-axis direction). That is, the semiconductor laser device 101 emits linearly polarized light whose electric field vibrates in the horizontal direction (y-axis direction) of the active layer. However, depending on the atomic arrangement constituting the active layer, the laser beam may be polarized in the vertical direction (x-axis direction) of the active layer.

FIG. 6 is a perspective view showing the configuration of the base 30 and the semiconductor laser elements 101 to 104. FIG. 7 is a cross-sectional view taken along the line AA'shown in FIG.

Each of the semiconductor laser elements 101 to 104 is driven by being supplied with an electric current, and heat is generated by the driving. Since sufficient heat dissipation is not performed only by the heat capacity of the stem 13, the temperature of the semiconductor laser chip becomes high, and a sudden decrease in light output may occur. Further, such an increase in heat load causes a shortening of the life of the semiconductor laser chip or thermal destruction of parts constituting the semiconductor laser element. Therefore, it is necessary to dissipate heat from the stem 13 to the base 30. In the first embodiment, the base 30 is made of a member having high thermal conductivity. The base 30 contains, for example, a metal material such as Cu or Al. Alternatively, for example, the base 30 contains a ceramic having a high thermal conductivity such as SiC and AlN. Alternatively, fins that improve the heat capacity and heat dissipation area of the stem 13 or a cooling member connected to a heat pipe filled with a refrigerant such as water may be added to the stem 13.

The semiconductor laser elements 101 to 104 are closely fixed to a flat surface formed on the upper surface 30A of the base 30 via grease or a sheet-shaped heat radiating material having high thermal conductivity. In order to further improve heat dissipation, it is preferable that each semiconductor laser element is solder-bonded to the base 30 with a solder material. The solder material contains, for example, SnAgCu, AuSn and the like as a main component.

Although the semiconductor laser elements 101 to 104 of the TO-Can package including the stem 13 and the base 30 are shown as separate members, the semiconductor laser chip is mounted on the member in which the stem 13 and the base 30 are integrated. It may have a configuration that is present. In that case, the heat dissipation of the laser light source device 1 is improved. Further, the semiconductor laser chips can be arranged at arbitrary intervals closer to each other without being restricted by the stem diameter, and the laser light source device 1 can be miniaturized.

Next, the details of the base 30 in the first embodiment will be described.

As described above, the base 30 is a flat plate, but the base 30 is not limited thereto, and the surface in contact with the stem 13 may be a flat surface. For example, the base 30 may be provided with a counterbore that matches the shape of the stem 13.

When the base 30 is a conductive material, it is necessary to ensure reliable insulation between the lead pin 14 of the semiconductor laser device and the base 30. The elongated holes 31 to 34 have a hole shape so that the lead pin 14 and the base 30 do not come into contact with each other, and are arranged so that the lead pin 14 and the base 30 do not come into contact with each other. The base 30 may have a round hole that can avoid contact between the lead pin 14 and the base 30 instead of the elongated holes 31 to 34. Alternatively, the base 30 has a groove structure that can avoid contact between the lead pin 14 and the base 30 and secure a wiring path for supplying a current from the semiconductor laser element 101 to 104 instead of the elongated holes 31 to 34. You may be.

Next, the details of the polarized light rotating elements 51 to 54 in the first embodiment will be described.

The polarization rotating elements 51 to 54 are made of, for example, an inorganic material or a resin material having birefringence. The inorganic material having birefringence is, for example, quartz. The resin material having birefringence is, for example, a resin containing polycarbonate or the like as a base material, which is stretched in one direction.

8 and 9 are views for explaining the operation of the polarizing rotating elements 51 and 53. 10 and 11 are diagrams for explaining the operation of the polarizing rotating elements 52 and 54. The speed of light propagating in a medium having a higher refractive index than air is slower than the speed of light propagating in air. That is, the higher the refractive index of a medium, the slower the speed of light propagating through that medium. Therefore, in the polarizing rotating element, the propagation speed of light whose electric field oscillates in the slow axis direction is slower than the propagation speed of light whose electric field oscillates in the fast axis direction.

The polarizing rotating elements 51 and 53 are 1/4 wave plates. As shown in FIG. 8, when the counterclockwise angle is positive, the speed axis (F axis) makes an angle of 45 ° with respect to the y axis, and the slow axis (S axis) is − Make an angle of 45 °. When the laser beam of linearly polarized light 81 parallel to the y-axis is incident on the polarizing rotating elements 51 and 53, the propagation of light rays in the slow axis (S axis) direction is relative to the propagation of light rays in the fast axis (F axis) direction. I'll be late. In the 1/4 wave plate, the propagation delay in the slow axis direction with respect to the fast axis direction is designed to be 1/4 wavelength. Since only the electric field in the slow axis direction propagates with a delay of 1/4 wavelength, the polarization of the laser light transmitted through the polarization rotating elements 51 and 53 changes with the passage of time as shown in FIG. For example, the polarization directions (vibration directions of the electric field) at times t0, t1, t2, and t3 are + F, −S, −F, and + S directions, respectively. In this way, the laser beam transmitted through the polarization rotating elements 51 and 53 travels so that the polarization direction spirals counterclockwise according to the operation of the left-hand screw. That is, the polarized light rotating elements 51 and 53 convert the polarization direction of the laser beam from the linearly polarized light 81 in the y-axis direction to the left-handed circularly polarized light 91 and 93.

The polarizing rotating elements 52 and 54 are also 1/4 wave plates. As shown in FIG. 10, the speed axis (F axis) forms an angle of −45 ° with respect to the y axis, and the slow axis (S axis) forms an angle of 45 ° with respect to the y axis. When the laser beam of linearly polarized light 81 parallel to the y-axis is incident on the polarizing rotating elements 52 and 54, only the electric field in the slow-axis direction propagates with a delay of 1/4 wavelength. The polarization of the laser light transmitted through the polarization rotating elements 52 and 54 changes with the passage of time as shown in FIG. For example, the polarization directions (vibration directions of the electric field) at the times t0, t1, t2, and t3 are the + S, −F, −S, and + F directions, respectively. In this way, the laser beam transmitted through the polarization rotating elements 52 and 54 travels so that the polarization direction spirals clockwise according to the operation of the right-handed screw. That is, the polarized light rotating elements 52 and 54 convert the polarization direction of the laser beam from the linearly polarized light 81 in the y-axis direction to the right-handed circularly polarized light 92 and 94.

Next, the detailed configuration of the spacer 20 and the lenses 41 to 44 in the first embodiment will be described.

FIG. 12 is a perspective view showing the configuration of the spacer 20 and the lenses 41 to 44. FIG. 13 is a cross-sectional view taken along the line BB'shown in FIG.

The laser beams 71 to 74 emitted from the laser light source device 1 are focused on the openings of the optical system of the projection type display device (not shown). Since the distance from the laser light source device 1 to the optical system opening of the projection type display device is not limited, it is preferable that the laser beams 71 to 74 emitted from the laser light source device 1 are parallel lights.

As described above, the spread laser light is emitted from each semiconductor laser element. In order to convert the laser light into parallel light, it is necessary to collect the laser light with a convex lens. As shown in FIG. 13, the lenses 41 to 44 have a plane on the incident surface (plane in the −z direction) and an axisymmetric spherical or aspherical convex surface on the exit surface (plane in the + z direction). That is, the lenses 41 to 44 are convex lenses. By arranging the laser emitting end faces of the semiconductor laser elements 101 to 104 near the focal positions of the lenses 41 to 44, the laser beams 71 to 74 transmitted through the lenses 41 to 44 are converted into parallel light.

The incident surfaces of the lenses 41 to 44 do not necessarily have to be flat. Each lens may have a concave or convex surface on the entrance surface or the exit surface as long as it has a function as a convex lens. However, the surface that may come into contact with the upper surface of the spacer 20 is preferably a flat surface.

Further, the emitting surface and the incident surface of each lens do not have to be a curved surface having axisymmetry. For example, each lens may be a cylindrical lens having a cylindrical surface on the emitting surface or the incident surface. The cylindrical lens converts the laser light emitted from the semiconductor laser element into parallel light only in the direction in which the spreading angle is large, that is, in the vertical direction (x-axis direction) with respect to the active layer.

The central axes 141 and 144 of the lenses 41 and 44 are arranged so as to coincide with the central axes of the light rays of the semiconductor laser elements 101 and 104, respectively. The lenses 41 and 44 are preferably fixed to the upper surface of the spacer 20 with an adhesive. It is sufficient that the lenses 41 and 44 can be fixed to the upper surface of the spacer 20, and the lenses 41 and 44 may be fixed by a member that holds down each lens from above. Although not shown in FIG. 13, the lenses 42 and 43 are also fixed to the upper surface of the spacer 20 in the same manner as the lenses 41 and 44.

The outer shapes of the spacer stepped portions 25 and 28 are similar to the outer shapes of the polarizing rotating elements 51 and 54. The outer shape of the spacer stepped portions 25 and 28 is larger than the outer shape of the polarizing rotating elements 51 and 54. Further, the height of the spacer step portions 25 and 28 is larger than the thickness of the polarizing rotating elements 51 and 54. Therefore, the polarizing rotation elements 51 and 54 are arranged so as to be housed in the space formed by the spacer step portions 25 and 28 and the bottom surfaces of the lenses 41 and 44 without protruding upward from the upper surface of the spacer 20. The outer shape of the spacer step portions 26 and 27 is the same as the outer shape of the spacer step portions 25 and 28.

Next, the operation of the laser light source device 1 will be described. The heat generated by driving the semiconductor laser elements 101 to 104 is dissipated to the base 30. Since each semiconductor laser element is separated, the heat generated by each semiconductor laser element is difficult to transfer to the adjacent semiconductor laser element. In this way, the laser light source device 1 suppresses the temperature rise of the semiconductor laser element.

Further, as shown in FIG. 1, the polarization directions of the laser beams 71 and 73 emitted from the semiconductor laser elements 101 and 103 are converted into left-handed circular polarizations 91 and 93 by the polarization rotating elements 51 and 53. .. On the other hand, the polarization directions of the laser beams 72 and 74 emitted from the semiconductor laser elements 102 and 104 are converted into right-handed circularly polarized light 92 and 94 by the polarization rotating elements 52 and 54. As a result, the laser light source device 1 emits the laser beams 71 and 73 of the circularly polarized light 91 and 93 rotating counterclockwise and the laser beams 72 and 74 of the circularly polarized light 92 and 94 rotating clockwise. That is, the polarization directions of the laser beams 71 to 74 change with time. Further, the circularly polarized light 91 and 93 have different polarization rotation directions from those of the circularly polarized lights 92 and 94. Although the laser beams 71 to 74 have the same cross-sectional shape (beam profile), the polarization directions are not aligned in one direction.

As described above, the laser light source device 1 emits two types of laser beams having different polarization directions by rotating the polarization directions of the plurality of laser beams by the polarization rotating elements 51 to 54. Such laser light reduces the occurrence of interference fringes and speckles.

Summarizing the above, the laser light source device 1 according to the first embodiment is a plurality of laser light source devices 1 that are individually held on the base 30 and the upper surface 30A of the base 30 and emit a plurality of laser beams whose polarization directions are aligned in one direction. The semiconductor laser elements 101 to 104 of the above, and a polarization conversion unit that disturbs the polarization directions of a plurality of laser beams so that they are not aligned in one direction by rotating the polarization directions of at least a part of the laser beams. ,including. The polarization conversion unit includes a plurality of polarization rotating elements 51 to 54 that convert the polarization of the plurality of laser beams into circular polarization. The plurality of polarized light rotating elements 51 to 54 are selectively arranged corresponding to the semiconductor laser elements 101 and 103 that emit a part of the laser light from the plurality of semiconductor laser elements 101 to 104, and the plurality of polarized light rotating elements 51 to 54 are selectively arranged. A first polarized light rotating element (polarized light rotating element 51, 54) that converts polarized light into left-handed circularly polarized light, and another that emits a part of laser light 72, 74 among a plurality of semiconductor laser elements 101 to 104. A second polarized rotating element (polarized light rotating element 52, 54) that is selectively arranged corresponding to the semiconductor laser elements 102, 104 and converts the polarized light of another part of the laser light 72, 74 into right-handed circularly polarized light. And, including.

The above laser light source device 1 is composed of a plurality of semiconductor laser elements 101 to 104 individually provided on a base 30 having good thermal conductivity. Therefore, the temperature rise due to laser oscillation is reduced, and the gain drop is suppressed.

Further, unlike the conventional array type laser light source, the laser light source device 1 is less likely to receive heat generated from the lasers on both sides of the central laser, and there is little possibility that the gain will be significantly reduced. Therefore, sufficient output can be obtained.

Further, the laser light source device 1 emits two types of circularly polarized laser light whose polarization direction changes with time. Since these two types of circularly polarized light are composed of left-handed circularly polarized light 91 and 93 that proceed while rotating counterclockwise and right-handed circularly polarized light 92 and 94, the two types of polarized light continuously coincide with each other. There is no such thing. The laser light source device 1 reduces the generation of interference fringes and speckles due to the synthesis of laser light.

Conventionally, when a laser light source is mounted on a projection type display device, a light diffusing element having a high degree of scattering is required in order to prevent deterioration of image quality due to interference fringes of laser light and speckle. However, a light diffusing element having a high degree of scattering reduces the efficiency of the light output of the projection type display device. On the other hand, in the laser light source device 1 shown in the first embodiment, interference fringes and speckles are reduced as described above. Therefore, the projection type display device equipped with the laser light source device 1 does not require a light diffusing element having a high degree of scattering. When the laser light source device 1 is mounted on the projection type display device, the generation of interference fringes and speckles is suppressed, so that the image quality is improved and the efficiency of the light output of the projection type display device itself is also improved.

Further, the laser light source device 1 in the first embodiment is provided corresponding to each of the plurality of semiconductor laser elements 101 to 104, and has a plurality of lenses 41 to 44 that convert each of the plurality of laser beams into parallel light. , Further include. The spacer 20 is fixed to the base 30 and holds a plurality of lenses 41 to 44.

With the above configuration, the laser light source device 1 makes it possible to emit laser light 71 to 74 having high output and high parallelism.

(Modification 1 of Embodiment 1)
The laser light source device according to the first modification of the first embodiment has different configurations of the spacer and the polarizing rotating element from those of the laser light source device 1 according to the first embodiment.

FIG. 14 is a diagram showing a configuration of a spacer 120 and polarization rotating elements 151 to 154 of the laser light source device according to the first modification of the first embodiment. The outer shape of the polarized rotating elements 151 to 154 has a parallelogram. The outer shape of the spacer step portions 125 to 128 of the spacer 120 has a parallelogram having a similar shape slightly larger than the outer shape of the polarization rotating elements 151 to 154. The outer shape of the spacer step portions 126 and 128 has a parallelogram in which the outer shape of the spacer step portions 125 and 127 is rotated by 90 ° in the xy plane.

Usually, the polarizing rotating element is cut out in a rectangular shape from a polarizing element substrate which is a larger plate material. Since the angle at which the rectangle is formed is 90 °, the polarizing rotating element is cut out from the polarizing element substrate without waste. On the other hand, the polarization rotating elements 151 to 154 in the present modification 1 are cut out at an angle with respect to one direction. FIG. 15 is a diagram showing a polarizing element substrate including the polarizing rotating elements 151 to 154. The speed axis 50A of the polarizing element substrate has an angle of 45 ° with respect to the y-axis, and the slow axis 50B has an angle of −45 ° with respect to the y-axis. The polarization rotating elements 151 to 154 are cut out at a slight angle α with respect to the x-axis direction. The outer shape of the polarizing rotating elements 151 to 154 has a parallelogram composed of one side parallel to the y-axis and the other side having an angle α with respect to the x-axis. That is, the speed axes 50A of the polarizing rotating elements 151 to 154 form an angle of 45 ° with respect to one side and an angle of 45 ° −α with respect to the other side intersecting with the other side at the stage of being cut out from the polarizing element substrate. ..

As shown in FIG. 14, the polarizing rotation elements 151 and 153 are arranged on the spacer step portions 125 and 127 while maintaining the directions of the speed axis 50A and the slow axis 50B. On the other hand, the polarizing rotating elements 152 and 154 cut out from the polarizing element substrate are rotated by 90 ° in the xy plane and arranged at the spacer step portions 126 and 128. Therefore, the speed axis 50A of the polarization rotating elements 152 and 154 forms an angle of 90 ° with respect to the speed axis 50A of the polarization rotating elements 151 and 153. As a result, the polarized rotating elements 151 and 153 function as left-handed polarized rotating elements, and the polarized rotating elements 152 and 154 function as right-handed polarized rotating elements.

As described above, the outer shape of the spacer step portions 125 to 128 has a parallelogram having a similar shape slightly larger than the outer shape of the polarizing rotating elements 151 to 154. Therefore, the polarizing rotation elements 151 to 154 are arranged at the spacer step portions 125 to 128 corresponding to the respective shapes, that is, at predetermined locations. The polarized light rotating element whose front and back sides are reversed does not fit into the spacer step portions 125 to 128. Such a spacer 120 limits the arrangement direction of the polarizing rotating elements 151 to 154 in the assembly process of the laser light source device or the like.

The outer shapes of the polarized rotating elements 152 and 154 are parallelograms having an angle β, and the outer shapes of the polarized rotating elements 151 and 154 are parallelograms having an angle α. The shape may be such that the difference from that for clockwise rotation is clear. The directions of the fast axis 50A and the slow axis 50B and the shapes of the spacer step portions 126 and 128 are appropriately set according to the rotation direction of the polarized light.

The laser light source device having such a configuration has the same effect as that of the first embodiment described above. Further, since the shapes of the polarizing rotating elements 151 to 154 correspond to the shapes of the spacer step portions 125 to 128, the arrangement direction of the polarizing rotating elements is limited. As a result, in the assembly process of the laser light source device, the mounting direction of the polarizing rotating element is specified, and the assembly workability is improved.

(Modification 2 of Embodiment 1)
The laser light source device according to the second modification of the first embodiment has different configurations of the spacer and the polarizing rotating element from those of the laser light source device 1 according to the first embodiment.

FIG. 16 is a diagram showing a configuration of a spacer 220 and polarization rotating elements 251 to 254 of the laser light source device according to the second modification of the first embodiment. The outer shape of the polarized rotating elements 251 to 254 has a parallelogram. The outer shape of the spacer stepped portions 225 to 228 of the spacer 220 has a parallelogram having a similar shape slightly larger than the outer shape of the polarization rotating elements 251 to 254. The outer shape of the spacer step portion 226 and 228 has a parallelogram in which the outer shape of the spacer step portion 225 and 227 is inverted with respect to the y-axis.

FIG. 17 is a diagram showing a polarizing element substrate including the polarizing rotating elements 251 to 254. The speed axis 50A of the polarizing element substrate has an angle of 45 ° with respect to the y-axis, and the slow axis 50B has an angle of −45 ° with respect to the y-axis. The polarization rotating elements 251 to 254 are cut out at a slight angle α with respect to the x-axis direction. The outer shape of the polarizing rotating elements 251 to 254 has a parallelogram composed of one side parallel to the y-axis and the other side having an angle α with respect to the x-axis. That is, the speed axes 50A of the polarizing rotating elements 251 to 254 form an angle of 45 ° with respect to one side and an angle of 45 ° −α with respect to the other side intersecting with the other side at the stage of being cut out from the polarizing element substrate. ..

As shown in FIG. 16, the polarizing rotation elements 251 and 253 are arranged on the spacer step portions 225 and 227 while maintaining the directions of the speed axis 50A and the slow axis 50B. On the other hand, the polarizing rotating elements 252 and 254 cut out from the polarizing element substrate are inverted with respect to the x-axis or the y-axis and arranged on the spacer stepped portions 226 and 228. Therefore, the speed axis 50A of the polarization rotating elements 252 and 254 forms an angle of 90 ° with respect to the speed axis 50A of the polarization rotating elements 251 and 253. As a result, the polarized light rotating elements 251 and 253 function as polarized light rotating elements that convert left-handed circular polarization, and the polarized light rotating elements 252 and 254 function as polarized light rotating elements that convert right-handed circular polarization.

As described above, the outer shape of the spacer step portion 225 to 228 has a parallelogram having a similar shape slightly larger than the outer shape of the polarizing rotating elements 251 to 254. Therefore, the polarization rotating elements 251 to 254 are arranged at the spacer step portions 225 to 228 corresponding to the respective shapes, that is, at predetermined locations. Such a spacer 220 is used in the assembly process of the laser light source device, etc., at the locations where the polarized light rotating elements 251 and 253 are converted to left-handed circular polarization, and the polarized light rotating elements 252 and 254 that are converted to clockwise circular polarization. Limit the location of.

The laser light source device having such a configuration has the same effect as that of the first embodiment described above. Further, since the shapes of the polarizing rotating elements 251 to 254 correspond to the shapes of the spacer step portions 225 to 228, the arrangement location of the polarizing rotating element is limited. As a result, in the assembly process of the laser light source device, the polarization rotating elements 251 and 253 that convert to left-handed circular polarization and the polarization-rotating elements 252 and 254 that convert to right-handing circular polarization are mistaken at designated locations. It can be arranged without any problem, and the assembly workability is improved.

Further, as shown in FIG. 16, the outer shape of the polarizing rotating elements 251 to 254 is determined according to the cross-sectional shape (beam profile) of the laser beams 71 to 74. The outer shape of the polarized rotating elements 251 to 254 has a parallelogram long in one direction. Each polarization rotating element is arranged so that the length of its parallelogram coincides with the x-axis direction in which the spread angle of each laser beam is large. That is, each polarization rotating element is selectively arranged according to the cross-sectional shape of each laser beam.

In this way, by cutting out the polarizing rotating element from the polarizing element substrate according to the cross-sectional shape of the laser beam, the number of polarized rotating elements that can be cut out from the polarizing element substrate increases. As a result, the cost of the polarizing rotating element and the laser light source device can be reduced.

Summarizing the above, the laser light source device according to the first and second modifications of the first embodiment further includes a spacer 120 (or 220) provided so as to cover the upper part of the plurality of semiconductor laser elements 101 to 104. The spacer 120 (or 220) includes a frame structure at a position through which each of the plurality of laser beams passes. Each of the plurality of polarized rotating elements 151 to 154 (or 251 to 254) is held in the frame structure. The outer shape of each of the plurality of polarized rotating elements 151 to 154 (or 251 to 254) has a parallelogram. The outer shape of the frame structure of the spacer 120 (or 220) has a similar shape larger than the outer shape of each of the plurality of polarization rotating elements 151 to 154 (or 251 to 254).

With such a configuration, the polarized light rotating elements 151, 153 (or 251 and 253) that convert to left-handed circular polarization, and the polarized light rotating elements 152, 154 (or 252, 254) that convert to right-handed circular polarization. The placement direction or placement location is limited. As a result, the assembling workability of the laser light source device is improved.

Further, in the laser light source device according to the second modification of the first embodiment, the first polarized rotating element (polarized rotating element 251, 253) or the second polarized rotating element (polarized rotating element 252, 254) has a plurality of laser beams. It is selectively arranged according to each cross-sectional shape.

With such a configuration, the yield of the polarizing rotating element that can be obtained from the polarizing element substrate is increased, and the cost of the polarizing rotating element and the laser light source device can be reduced.

<Embodiment 2>
The laser light source device according to the second embodiment will be described. The same configuration and operation as in the first embodiment will not be described.

FIG. 18 is a perspective view showing the configuration of the laser light source device 100 according to the second embodiment and the laser beams 171 to 174 emitted from the laser light source device 100. FIG. 19 is an exploded perspective view showing the configuration of the laser light source device 100. FIG. 20 is a perspective view showing the configuration of the spacer 320 and the polarizing rotating elements 51 to 54. FIG. 21 is a cross-sectional view taken along the line CC'shown in FIG. In each of the drawings in the second embodiment, the same reference numerals as those in the drawings shown in the first embodiment indicate the same or corresponding portions.

The laser light source device 100 has a configuration in which a base 30, semiconductor laser elements 101 to 104, spacers 320, lenses 41 to 44, and polarization rotating elements 51 to 54 are arranged in order from the bottom. In the laser light source device 100, the structure of the spacer 320 for fixing the lenses 41 to 44 and the polarization rotating elements 51 to 54 is different from the structure of the spacer 20 of the first embodiment.

The spacer 320 includes spacer window portions 321 to 324, lens holding step portions 361 to 364, and polarizing rotating element holding step portions 325 to 328.

The spacer windows 321 to 324 include openings through which each of the plurality of laser beams 171 to 174 passes. Here, the outer shape of the opening is circular, similar to the lenses 41 to 44. Also, the diameter of the aperture is slightly larger than the diameter of the lenses 41 to 44.

The lens holding step portions 361 to 364 include a step formed by providing an opening smaller than the opening inside the opening of the spacer window portions 321 to 324. In other words, the lens holding step portions 361 to 364 are steps provided on the inner circumference of the spacer window portions 321 to 324. Here, the outer shape of the small opening constituting the lens holding step portions 361 to 364 is circular like the lenses 41 to 44. Also, the diameter of the small aperture is smaller than the diameter of the lenses 41 to 44. Since the spacer window portions 321 to 324 and the lens holding step portions 361 to 364 have such a configuration, the lenses 41 to 44 inserted into the spacer window portions 321 to 324 become the lens holding step portions 361 to 364. It is fixed.

The polarization rotating element holding step portions 325 to 328 are steps provided above the lens holding step portions 361 to 364, and include a step formed by an opening larger than the openings of the spacer window portions 321 to 324. In other words, the polarization rotating element holding step portions 325 to 328 are steps provided on the outer periphery of the spacer window portions 321 to 324. Here, the outer shape of the polarization rotating element holding step portions 325 to 328 has a similar shape slightly larger than the outer shape of the polarizing rotating elements 51 to 54. Further, the outer shape of the polarization rotating elements 51 to 54 is larger than the diameter of the opening of the spacer window portions 321 to 324. Therefore, the polarization rotating elements 51 to 54 are held by the polarization rotating element holding step portions 325 to 328 without falling into the openings of the spacer window portions 321 to 324, and the arrangement of the polarization rotating elements 51 to 54 is restricted. ..

The position of the polarization rotating element holding step portions 325 to 328 with respect to the lens holding step portions 361 to 364 in the height direction is higher than the tops of the lenses 41 to 44 fixed to the lens holding step portions 361 to 364. In other words, the polarizing rotating elements 51 to 54 are held above the lenses 41 to 44 by the polarizing rotating element holding step portions 325 to 328. With such a configuration, the lenses 41 to 44 fixed to the lens holding step portions 361 to 364 and the polarizing rotating elements 51 to 54 held by the polarizing rotating element holding step portions 325 to 328 do not interfere with each other. Can be placed.

The position of the polarization rotating element holding step portions 325 to 328 with respect to the upper surface of the spacer 320 in the height direction is not limited in relation to the thickness of the polarization rotating elements 51 to 54 as long as the positions of the polarizing rotating elements 51 to 54 can be regulated. However, it is preferable that the polarization rotating element holding step portions 325 to 328 are located at a position lower than the thickness of the polarization rotating elements 51 to 54 from the upper surface of the spacer 320. In this case, since the polarization rotating elements 51 to 54 held by the polarization rotating element holding step portions 325 to 328 do not protrude upward from the upper surface of the spacer 320, damage to the polarization rotating elements 51 to 54 can be suppressed.

The polarization rotating elements 51 to 54 form a polarization conversion unit as in the first embodiment. The polarization conversion unit rotates the polarization direction of at least a part of the laser light 171 to 174 parallelized by the semiconductor laser elements 101 to 104 and the lenses 41 to 44, and the polarization direction of the laser light 171 to 174 is changed. Disturb so that they are not aligned in one direction. The polarized light rotating elements 51 and 53 in the second embodiment convert the polarization directions of some of the laser beams 171 to 174 of the laser beams 171 to 174 into counterclockwise circular polarization. Further, the polarized light rotating elements 52 and 54 convert the polarization direction of the laser beams 172 and 174 into right-handed circular polarization. In other words, the polarization rotating elements 51 to 54 are selectively arranged corresponding to the semiconductor laser elements 101 to 104 that emit the laser light 171 to 174.

The laser beams 171 to 174 emitted from the semiconductor laser element 101 to 104 are converted into laser beams 171 to 174 parallel to the z-axis direction by the lenses 41 to 44. Then, the parallelized laser beams 171 to 174 are uniformly incident on the entire region of the polarization rotating elements 51 to 54. The rotation of polarized light is determined by the optical path length when passing through the polarized light rotating elements 51 to 54. If the optical path length is not appropriate, a component with insufficient rotation of polarized light is generated. For example, when a light beam inclined obliquely with respect to the surface of the polarized light rotating element is incident on the polarized light rotating element, the optical path length of the laser beam transmitted through the polarized light rotating element becomes long, so that a component having insufficient polarization rotation is contained. appear. According to the second embodiment, since the laser beams 171 to 174 are parallelized before the polarization rotating elements 51 to 54 are incident, the polarized light rotates uniformly in the entire region.

The linearly polarized light in the y-axis direction of the laser beams 171 and 173 emitted from the semiconductor laser elements 101 and 103 is converted into left-handed circularly polarized light 191 and 193 by the polarization rotating elements 51 and 53. On the other hand, the linearly polarized light in the y-axis direction of the laser beams 172 and 174 emitted from the semiconductor laser elements 102 and 104 is converted into right-handed circularly polarized light 192 and 194 by the polarization rotating elements 52 and 54. As a result, the left-handed circularly polarized 191 and 193 laser beams 171 and 173 and the right-handed circularly polarized 192 and 194 laser beams 172 and 174 are emitted from the laser light source device 100. That is, the polarization directions of the laser beams 171 to 174 change with time. Further, the circularly polarized light 191 and 193 have different polarization rotation directions from the circularly polarized light 192 and 194. The laser beams 171 to 174 emit laser beams having the same cross-sectional shape (beam profile) but whose polarization directions are not aligned in one direction.

As described above, the laser light source device 100 has two types in which the polarization directions are different by rotating the polarization directions of some of the laser beams 171 to 174 out of the plurality of laser beams 171 to 174 by the polarization rotating elements 52 to 54. The laser beam 171 to 174 of the above is emitted. Such laser beams 171 to 174 reduce the occurrence of interference fringes and speckles.

The outer shape of the spacer window portions 321 to 324 may have other shapes such as a rectangle as long as the arrangement of the lenses 41 to 44 can be regulated. Further, the diameter of the opening of the spacer window portions 321 to 324 may be sufficiently larger than the diameter of the lenses 41 to 44. In such a configuration, as shown in FIG. 21, the light emitting center (not shown) of the semiconductor laser element and the lenses 41 and 44 are aligned with the central axes 141 and 144 of the spacer windows 321 and 324. Can be adjusted.

Further, the outer shape of the opening forming the lens holding step portions 361 to 364 may be a rectangular shape or an elliptical shape matching the cross-sectional shape of the laser beams 171 to 174.

As long as the polarization rotating elements 51 to 54 do not fall into the spacer window portions 321 to 324, the outer shape of the polarization rotating elements 51 to 54 is the same as the opening of the lens holding step portions 361 to 364. The outer shape of the lens may also be a rectangle or an ellipse that matches the cross-sectional shape of the laser beams 72 and 74. Such a structure makes it possible to minimize the size of the polarizing rotating elements 51 to 54, and realizes cost reduction.

Summarizing the above, the laser light source device 100 according to the second embodiment includes a plurality of lenses 41 to 44. The plurality of lenses 41 to 44 are provided corresponding to each of the plurality of semiconductor laser elements 101 to 104, and convert the plurality of laser beams 171 to 174 into parallel light. Further, the laser light source device 100 according to the second embodiment includes a spacer 320 instead of the spacer 20 according to the first embodiment. The spacer 320 is provided so as to cover the upper part of the plurality of semiconductor laser elements 101 to 104. The spacer 320 includes spacer window portions 321 to 324, lens holding step portions 361 to 364, and polarizing rotating element holding step portions 325 to 328. The spacer windows 321 to 324 include openings through which each of the plurality of laser beams 171 to 174 passes. The lens holding step portions 361 to 364 include a step formed by providing an opening smaller than the opening inside the opening of the spacer window portions 321 to 324. The lens holding step portions 361 to 364 hold the lenses 41 to 44 in the step. Further, the polarization rotating element holding step portions 325 to 328 are steps provided above the lens holding step portions 361 to 364, and include a step formed by an opening larger than the openings of the spacer window portions 321 to 324. The upper direction corresponds to the direction in which the plurality of laser beams 171 to 174 travel. The polarization rotating element holding step portions 325 to 328 hold the polarization rotating elements 51 to 54 on the upper part of the lenses 41 to 44 corresponding to the polarization rotating elements 51 to 54 among the plurality of lenses 41 to 44.

In such a laser light source device 100, the parallelized laser beams 171 to 174 are uniformly incident on the entire region of the polarizing rotating elements 51 to 54. Since the laser beams 171 to 174 are parallelized before the polarization rotating elements 51 to 54 are incident, the polarized light rotates uniformly in the entire region.

(Modified Example of Embodiment 2)
The laser light source device in the modified example of the second embodiment has different configurations of the spacer and the polarizing rotating element from those of the laser light source device 100 in the second embodiment.

FIG. 22 is a diagram showing the configuration of the spacer 420 of the laser light source device and the polarization rotating elements 151 to 154 in the modified example of the second embodiment. The outer shape of the polarized rotating elements 151 to 154 has a parallelogram. The outer shape of the polarization rotating element holding step portions 425 to 428 of the spacer 420 has a parallelogram having a similar shape slightly larger than the outer shape of the polarization rotating elements 151 to 154.

When the front and back sides of the polarization rotating elements 151 to 154 are reversed, the polarization rotating elements 151 to 154 do not fit into the polarization rotating element holding step portions 425 to 428. Therefore, the installation directions of the polarizing rotating elements 151 to 154 are limited.

The method of manufacturing the polarized rotation rotating elements 151 to 154 is the same as the description of FIG. 15 of the modified example of the first embodiment, and details thereof will be omitted here.

Even with a laser light source device having such a configuration, the same effect as that of the second embodiment can be obtained. Further, since the installation directions and installation positions of the polarizing rotation elements 151 to 154 are limited, the workability in the assembly process of the laser light source device is improved.

In the above-described first or second embodiment and each modification, a laser light source device in which two semiconductor laser elements are arranged in the x-axis direction and two (2 × 2) semiconductor laser elements are arranged in the y-axis direction is shown as an example. However, the number of semiconductor laser elements mounted on the laser light source device is not limited to that. The laser light source device may include a plurality of semiconductor laser elements whose number is increased in the x-axis direction and the y-axis direction. With such a configuration, a high-power laser light source device can be realized. Further, the arrangement of the semiconductor laser elements may be a two-dimensional array such as 2 × 4, 4 × 4, or a one-dimensional array such as 1 × 4.

Further, when the arrangement pitches of the semiconductor laser elements in adjacent rows or columns are offset by half a pitch from each other, the closest arrangement is possible. Such a configuration reduces the effective diameter of the condenser lens, and contributes to miniaturization and cost reduction of the projection type display device.

Further, when each of the semiconductor laser elements oscillates a laser having a different wavelength, the laser light source device can further reduce the occurrence of interference and speckle. For example, when the semiconductor laser elements 101 and 102 oscillate a red laser having a wavelength of 638 nm and the semiconductor laser elements 103 and 104 oscillate a red laser having a wavelength of 642 nm, the laser light source device determines the above-mentioned polarization rotation direction. Not only that, it is possible to emit four types of laser beams having different characteristics with respect to wavelength.

<Embodiment 3>
The laser light source device according to the third embodiment will be described. FIG. 23 is a perspective view showing the configuration of the laser light source device 500 of the third embodiment and the laser beams 571 to 576 emitted from the laser light source device 500. FIG. 24 is a diagram showing the configuration of the spacer 520 and the polarization rotating elements 551 to 556 in the third embodiment.

Six semiconductor laser elements are arranged on the base 530 (not shown). From each semiconductor laser element, laser light 571 to 576 is emitted via the lenses 541 to 546 held by the spacer 520 and the polarization rotating elements 551 to 556.

The plurality of semiconductor laser elements are configured to selectively emit laser beams of different colors. The laser beams 571 and 572 are blue lasers of 445 to 475 nm, the laser beams 573 and 574 are green lasers of 520 to 550 nm, and the laser beams 575 and 576 are red lasers of 630 to 660 nm.

In any of the semiconductor lasers, the horizontal direction of the active layer of the semiconductor laser chip is arranged in the y-axis direction, and the laser beam has linearly polarized light that vibrates in the y-axis direction.

The blue laser light 571 emitted from the semiconductor laser element is converted into parallel light by the lens 541. Further, the parallel light is transmitted through the polarized light rotating element 551, and a blue laser beam 571 having a left-handed circularly polarized light 591 is emitted in the z-axis direction. The blue laser light 572 is converted into parallel light by the lens 542. Further, the parallel light is transmitted through the polarized light rotating element 552, and a blue laser beam 572 having a right-handed circularly polarized light 592 is emitted in the z-axis direction. Similarly, a green laser beam 573 having a left-handed circular polarization 593 and a green laser light 574 having a right-handed circular polarization 594 are emitted in the z-axis direction. Similarly, a red laser beam 575 having a left-handed circular polarization 595 and a red laser light 576 having a right-handed circular polarization 596 are emitted in the z-axis direction.

Note that the semiconductor laser may emit linearly polarized light in the x-axis direction depending on the atomic arrangement constituting the active layer, and the arrangement of the left-handed polarized light rotating element and the right-handed polarized light rotating element is not limited to the example of the third embodiment. The location is appropriately selected.

When the polarizing rotating element is a retardation plate, the retardation ΔΦ, the thickness d of the retardation plate, the wavelength λ, and the refractive index difference Δn of the fast axis 50A and the slow axis 50B satisfy the following equation (1).

A retardation plate having specifications in which the thickness d of the retardation plate or the refractive index difference Δn differs depending on the wavelength λ of the laser beam is required. Further, the specifications of the non-reflective coating film for reducing the light loss of the retardation plate also differ in the optimum value depending on the wavelength λ. Therefore, the specifications of the polarizing rotating elements 551 to 556 differ depending on the color of the laser beam. In the third embodiment, the polarized rotating elements 551 and 552 are polarized rotating elements for blue, the polarized rotating elements 555 and 554 are polarized rotating elements for green, and the polarized rotating elements 555 and 556 are polarized light for red. It is a rotating element.

The polarization rotating elements 551 to 556 have different outer angles forming parallelograms. The angles of the polarization rotating elements 551 and 552 are α1, the angles of the polarization rotating elements 555 and 554 are α2, and the angles of the polarization rotating elements 554 and 555 are α3. In the third embodiment, a left-handed circularly polarized light element is required as the polarized light-rotating element 551, and a right-handed circularly polarized lighting element is required as the polarized light-rotating element 552. Here, by rotating one type of circularly polarized light element by 90 °, it is possible to use the circularly polarized light element properly as two circularly polarized light elements, one for left rotation and the other for right rotation. The outer shape of the polarization rotating element holding step portions 561 and 562 formed on the spacer 520 is a shape similar to the outer shape of the polarization rotating elements 551 and 552 forming a parallelogram at an angle α1. Further, the polarization rotating element holding step portions 561 and 562 are formed in a relationship of being rotated by 90 °. Therefore, the polarization rotating elements 551 and 552 are fitted and held in the polarization rotating element holding step portions 561 and 562, respectively. The same applies to the relationship between the outer shape of the polarizing rotating elements 535 and 554 forming a parallelogram at an angle α2 and the outer shape of the polarizing rotating element holding step portions 563 and 564. Further, the relationship between the outer shape of the polarized light rotating element 555 and 556 forming the angle α3 and the outer shape of the polarized light rotating element holding step portion 565 and 566 is also the same.

The parallelogram polarization rotating elements 551 and 552 forming an angle α1 include a parallelogram polarization rotating element holding step portion 563 and 564 forming an angle α2 and a parallelogram polarization rotating element holding step portion 565 forming an angle α3. Cannot fit into 566. Further, since the polarization rotating element 551 has a shape in which the outer shape of the polarization rotating element 552 is rotated by 90 °, it cannot be fitted to the polarization rotating element holding step portion 562. In other words, the polarized light rotating element 551 for blue is arranged only in the polarized light rotating element holding step portion 561, and the polarized light rotating element 552 is arranged limited to the polarized light rotating element holding step portion 562. Similarly, the parallelogram-shaped polarization rotating element 553 for green having an angle α2 is arranged only in the polarization rotating element holding step portion 563, and the polarization rotating element 554 is arranged only in the polarization rotating element holding step portion 564. Further, the polarization rotating element 555 for red, which is a parallelogram having an angle α3, is arranged only in the polarization rotating element holding step portion 565, and the polarization rotating element 556 is arranged only in the polarization rotating element holding step portion 566.

In this way, by changing the angle α of the parallelogram of the polarizing rotating element having different specifications according to the color of the laser, it is possible to configure the combination of the colored light of the laser and the polarized rotating element without making a mistake.

Further, the polarized rotating element 551 for left rotation can be used as a polarized rotating element 552 for right rotation by inverting the front and back sides thereof, and depending on the configuration of such a polarized rotating element, polarization is performed. The shapes of the rotating element holding step portions 561 and 562 may be formed.

The laser light source device 500 configured as described above provides a light source suitable for a color image by laser light of three colors of blue, green, and red. Since the polarization rotating element is optimally designed according to the color of the laser, the laser light source device 500 generates a laser beam having low loss and containing no unnecessary polarization component. A plurality of laser beams having different directions of rotation of polarized light reduce the occurrence of interference fringes and speckles.

The semiconductor laser element is not limited to visible light, and an ultraviolet laser or an infrared laser may be applied depending on the application.

In the third embodiment, the laser light source device 500 configured in the order of the lens and the polarized light rotating elements 551 to 556 from the semiconductor laser element side is shown as an example, but the laser light source device configured in the order of the polarized light rotating element and the lens is used. Even if there is, the same effect as above is obtained.

<Embodiment 4>
The laser light source device according to the fourth embodiment will be described. FIG. 25 is a perspective view showing the configuration of the laser light source device 600 according to the fourth embodiment and the laser beams 671 to 674 emitted from the laser light source device 600. FIG. 26 is an exploded perspective view showing the configuration of the laser light source device 600 according to the fourth embodiment.

The laser light source device 600 includes semiconductor laser elements (not shown) arranged in a 4 × 4 matrix, one lens array 660, and four polarization rotating elements 651 to 654. The 4x4 semiconductor laser device is arranged on the base 630. The horizontal direction of the active layer of each semiconductor laser chip is arranged in the y-axis direction, and linearly polarized laser light in the y-axis direction is emitted.

The lens array 660 is a lens in which single lenses arranged in 4 × 4 are integrated. Each of the 16 single lenses is arranged corresponding to 16 semiconductor laser elements. The 16 semiconductor laser elements and one lens array 660 emit 16 parallelized laser beams in the z-axis direction. In FIG. 25, some of the 16 laser beams are not shown.

The polarization rotating elements 651 to 654 have a long parallelogram and convert four laser beams emitted from four semiconductor laser elements arranged in a row in the x direction into circular polarization. Here, the polarization rotating elements 651 and 653 convert the laser beams 671 and 673 into left-handed circularly polarized light 691 and 693. The polarization rotating elements 652 and 654 convert the laser beams 672 and 674 into right-handed circularly polarized light 692 and 694.

If the x direction is defined as the row direction and the y direction is defined as the column direction, the polarization rotating element 651 for left rotation is arranged in one row. The polarization rotating element 651 converts the laser beam 671 into a left-handed circularly polarized light 691. A polarization rotating element 652 for clockwise rotation is provided in a row adjacent to the row in which the polarization rotating element 651 is provided. The polarization rotating element 652 converts the laser beam 672 into a clockwise rotating circularly polarized light 692. A polarization rotating element 653 for left rotation is arranged in a row adjacent to the row in which the polarization rotating element 652 is provided. The polarization rotating element 653 converts the laser beam 673 into a left-handed circularly polarized light 693. Further, a polarization rotating element 654 for right rotation is arranged in a row adjacent to the row in which the polarization rotating element 653 is provided. The polarization rotating element 654 converts the laser beam 674 into a clockwise rotating circularly polarized light 694. As described above, the laser beam in the row containing the laser beams 681 and 683 and the laser beam in the row containing the laser beams 672 and 674 have different polarization rotation directions. That is, two types of polarized laser light are emitted from the laser light source device 600.

The spacer 620 includes the polarization rotating element holding step portions 661A and 661B. The shape of the polarizing rotating element 651 is a parallelogram forming an angle α, and the shapes of the polarizing rotating element holding step portions 661A and 661B are wedge shapes forming an angle α. The polarization rotating element 651 is fitted and held in the polarization rotating element holding step portions 661A and 661B formed on the spacer 620. The spacer 620 includes the polarization rotating element holding step portions 662A and 662B. The shape of the polarizing rotating element 652 is a parallelogram forming an angle β, and the shapes of the polarizing rotating element holding step portions 662A and 662B are wedge shapes forming an angle β. The polarization rotating element 652 is fitted and held in the polarization rotating element holding step portions 662A and 662B formed on the spacer 620. Similarly, the polarization rotating element 653 having the same shape as the polarization rotating element 651 is fitted and held in the polarization rotating element holding step portions 663A and 663B formed in the spacer 620 and having a wedge shape at an angle α. The polarization rotating element 654 having the same shape as the polarization rotating element 652 is fitted and held in the polarization rotating element holding step portions 664A and 664B formed in the spacer 620 at an angle β. With such a configuration, the polarizing rotating elements 651 to 654 are mounted at the specified locations.

The laser light source device 600 of the fourth embodiment enables the emission of a beam having a high output and a high degree of parallelism. Two types of circularly polarized laser beams having different polarization rotation directions reduce the occurrence of interference fringes and speckles. Further, when the arrangements of the plurality of semiconductor laser elements are densely integrated and the adjacent laser beams are closely spaced, the arrangements of the single lenses for parallelizing the laser beams interfere with each other. However, a lens array 660 in which a plurality of single lenses are integrated is applied to the laser light source device 600 according to the fourth embodiment. Therefore, such interference does not occur, and the laser light source device 600 can be miniaturized. Similarly, when the adjacent laser beams are close to each other, a structure for holding individual polarizing rotating elements as shown in the first to third embodiments is required. However, in the laser light source device 600 according to the fourth embodiment, each of the polarization rotating elements 651 to 654 converts the polarized light of the four laser beams into circular polarization. Therefore, the holding structure of the polarizing rotating element is simplified, and the laser light source device 600 can be miniaturized.

If the polarized rotation element 651 can be used even if it is turned upside down, it can be used as a polarized light rotating element 652 for right rotation by inverting the polarization rotating element 651 for left rotation. In that case, the wedge shapes of the polarization rotating element holding step portions formed on the spacer 620 are all formed at an angle α. As a result, the polarizing rotating element is standardized, which leads to cost reduction.

The polarization rotating elements 651 to 654 may have a shape long in the y direction (column direction). It suffices if the laser beam can be transmitted according to the cross-sectional shape of the laser beam 671 to 674, and the polarization rotating elements 651 to 654 having a shape long in the x direction (row direction) can further shorten the short side direction and rotate the polarization. This leads to a reduction in the cost of the element.

The laser light source device according to the above embodiment converts all the laser light emitted from the semiconductor laser element into circular polarization, but is not limited to such a configuration. Linearly polarized light is obtained by omitting the arrangement of the polarized light rotating element for some laser light and maintaining the linearly polarized light as it is, or by arranging a 1/2 wave plate on the polarized light rotating element for some laser light. Different polarized light may be added to the circularly polarized light, such as adding. In the present invention, each embodiment can be freely combined, and each embodiment can be appropriately modified or omitted within the scope of the invention.

Although the present invention has been described in detail, the above description is exemplary in all aspects and the present invention is not limited thereto. It is understood that innumerable variations not illustrated can be assumed without departing from the scope of the present invention.

1 Laser light source device, 100 laser light source device, 500 laser light source device, 600 laser light source device, 101-104 semiconductor laser element, 20 spacer, 120 spacer, 220 spacer, 320 spacer, 420 spacer, 520 spacer, 620 spacer, 25- 28 Spacer stepped portion, 125-128 Spacer stepped portion, 225-228 Spacer stepped portion, 361-364 Lens holding stepped portion, 325-328 Polarized rotating element holding stepped portion, 561-565 Polarized rotating element holding stepped portion, 661A to 664A Polarized rotating element holding step, 661B to 664B Polarized rotating element holding step, 30 base, 30A upper surface 41-44 lens, 541-546 lens, 660 array lens, 50A fast axis, 50B slow axis, 51-54 polarized rotation Elements, 551-556 polarized rotating elements, 651-654 polarized rotating elements, 151-154 polarized rotating elements, 251-254 polarized rotating elements, 71-74 laser light, 171-174 laser light, 571-576 laser light, 617- 674 laser light, 81 linearly polarized light, 91-94 circularly polarized light, 191-194 circularly polarized light, 591-596 circularly polarized light, 691-694 circularly polarized light.

The laser light source device according to the present invention includes a base, a plurality of semiconductor laser elements each individually held on the upper surface of the base, and emitting a plurality of laser beams having the same polarization direction in one direction, and a plurality of laser beams. A polarization conversion unit that disturbs the polarization directions of a plurality of laser beams so that they are not aligned in one direction by rotating the polarization directions of at least a part of the laser beams, and a spacer provided over the top of the plurality of semiconductor laser elements. And, including. The polarization conversion unit includes a plurality of polarization rotating elements that convert the polarization of a plurality of laser beams into circular polarization. The plurality of polarized light rotating elements are selectively arranged corresponding to the semiconductor laser element that emits a part of the laser light among the plurality of semiconductor laser elements, and the polarized light of the part of the laser light is converted into the circularly polarized light that rotates counterclockwise. The first polarized light rotating element and another semiconductor laser element that emits another part of the laser light among the plurality of semiconductor laser elements are selectively arranged to polarize the other part of the laser light. Includes a second polarized rotating element that converts to right-handed circularly polarized light. The spacer includes a frame structure provided at a position through which each of the plurality of laser beams passes. The frame structure holds each of the plurality of polarized rotating elements. The outer shape of the frame structure of the spacer has a similar shape larger than the outer shape of each of the plurality of polarizing rotating elements. The frame structure includes a first spacer stepped portion for holding the first polarized rotating element and a second spacer stepped portion for holding the second polarized rotating element. The outer shape of the first spacer step portion is different from the outer shape of the second spacer step portion.

Summarizing the above, the laser light source device 1 according to the first embodiment is a plurality of laser light source devices 1 that are individually held on the base 30 and the upper surface 30A of the base 30 and emit a plurality of laser beams whose polarization directions are aligned in one direction. The semiconductor laser elements 101 to 104 of the above, and a polarization conversion unit that disturbs the polarization directions of a plurality of laser beams so that they are not aligned in one direction by rotating the polarization directions of at least a part of the laser beams. ,including. The polarization conversion unit includes a plurality of polarization rotating elements 51 to 54 that convert the polarization of the plurality of laser beams into circular polarization. The plurality of polarization rotating elements 51 to 54 are selectively arranged corresponding to the semiconductor laser elements 101 and 103 that emit a part of the laser light from the plurality of semiconductor laser elements 101 to 104, and the plurality of polarized light rotating elements 51 to 54 are arranged to correspond to the semiconductor laser elements 101 and 103. A first polarized light rotating element (polarized light rotating element 51, 53 ) that converts polarized light into left-handed circularly polarized light, and another that emits a part of laser light 72, 74 among a plurality of semiconductor laser elements 101 to 104. A second polarized rotating element (polarized light rotating element 52, 54) that is selectively arranged corresponding to the semiconductor laser elements 102, 104 and converts the polarized light of another part of the laser light 72, 74 into right-handed circularly polarized light. And, including.

Claims (9)

With the base
A plurality of semiconductor laser elements, each of which is individually held on the upper surface of the base and emits a plurality of laser beams whose polarization directions are aligned in one direction.
A polarization conversion unit that disturbs the polarization directions of the plurality of laser beams so that they are not aligned in one direction by rotating the polarization directions of at least a part of the plurality of laser beams is provided.
The polarization conversion unit
A plurality of polarization rotating elements for converting the polarization of the plurality of laser beams into circular polarization are included.
The plurality of polarized rotating elements are
A first polarization rotation that is selectively arranged corresponding to a semiconductor laser element that emits a part of the laser light among the plurality of semiconductor laser elements and converts the polarization of the part of the laser light into a left-handed circularly polarized light. With the element
It is selectively arranged corresponding to another semiconductor laser element that emits another part of the laser light among the plurality of semiconductor laser elements, and the polarized light of the other part of the laser light is converted into right-handed circularly polarized light. A laser light source device including a second polarized rotating element to be converted. Further, a spacer provided so as to cover the upper part of the plurality of semiconductor laser elements is provided.
The spacer includes a frame structure at a position through which each of the plurality of laser beams passes.
Each of the plurality of polarization rotating elements is held in the frame structure.
The outer shape of each of the plurality of polarized rotating elements has a parallelogram.
The laser light source device according to claim 1, wherein the outer shape of the frame structure of the spacer has a similar shape larger than the outer shape of each of the plurality of polarizing rotating elements. The laser light source device according to claim 2, wherein the first polarized rotating element or the second polarized rotating element is selectively arranged according to the cross-sectional shape of each of the plurality of laser beams. A plurality of lenses provided corresponding to each of the plurality of semiconductor laser elements and converting each of the plurality of laser beams into parallel light are further provided.
The laser light source device according to claim 2 or 3, wherein the spacer is fixed to the base and holds the plurality of lenses. Further, a spacer provided so as to cover the upper part of the plurality of semiconductor laser elements is provided.
The spacer is
A spacer window through which each of the plurality of laser beams passes, and
The lens holding step portion provided on the inner circumference of the spacer window portion and the lens holding step portion
Includes a polarization rotating element holding step portion provided on the outer periphery of the spacer window portion.
The laser light source device according to claim 1, wherein each of the plurality of polarization rotating elements is held by the polarization rotating element holding step portion. The outer shape of each of the plurality of polarized rotating elements has a parallelogram.
The laser light source device according to claim 5, wherein the outer shape of the polarized light rotating element holding step portion has a similar shape larger than the outer shape of each of the plurality of polarized rotating elements. A plurality of lenses provided corresponding to each of the plurality of semiconductor laser elements and converting each of the plurality of laser beams into parallel light are further provided.
The spacer is fixed to the base and
Each of the plurality of lenses is held at the lens holding step portion, and is held.
The laser light source device according to claim 5 or 6, wherein the polarization rotating element holding step portion holds each of the plurality of polarization rotating elements on an upper portion of each of the plurality of lenses. The laser light source device according to any one of claims 1 to 7, wherein the plurality of semiconductor laser elements are configured to selectively emit the plurality of laser beams having different colors. The polarization conversion unit
Any one of claims 1 to 8 in which the polarization directions of two or more laser beams emitted from two or more adjacent semiconductor laser elements among the plurality of semiconductor laser elements are rotated by one polarization rotating element. The laser light source device according to the section.

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