JP2007115929A - Semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the alignment precision of a mirror without reducing heat radiation properties in a simple manufacturing process, and to improve the position precision of a light axis to laser beams emitted from each laser. <P>SOLUTION: The interval of each emission point is determined by the positions of beam steering mirrors 907, 914 and the film thickness of a dielectric film 919 formed by a manufacturing process that can be controlled precisely, by allowing end faces where the beam steering mirrors 907, 914 are formed to butt each other for packaging, when packaging a plurality of semiconductor lasers formed monolithically. Thus, the position precision of the light axis can be improved and the interval between respective emission points can be controlled easily to laser beams emitted from each laser without reducing heat radiation properties by a simple manufacturing process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device in which a plurality of light sources used mainly for light sources of optical disks and the like are mounted.

  Semiconductor lasers are widely used in many fields of electronics and optoelectronics, and are indispensable as optical devices. In particular, optical disc devices such as CD (compact disc) and DVD (digital versatile disc) are currently actively used as large-capacity recording media. Furthermore, in order to record high-definition video, in recent years, a standard such as Blu-ray Disc (BD) has begun to appear as a next-generation DVD. A recording medium (media) used for a DVD has a smaller pit length and track interval than a CD medium. Therefore, the wavelength of the semiconductor laser used is also shortened as CD> DVD> BD according to the recording capacity. Specifically, the oscillation wavelength of the CD laser is in the 780 nm band, whereas the oscillation wavelength of the DVD laser is in the 650 nm band, and the oscillation wavelength of the BD laser is in the 400 nm band.

  In order for one optical disk device to detect both CD and DVD information, two light sources, a 780 nm band laser (infrared semiconductor laser) and a 650 nm band laser (red semiconductor laser) are required. 2. Description of the Related Art In recent years, in order to reduce the size and weight of an optical pickup device that constitutes an optical disk device, a two-wavelength semiconductor laser element that emits laser light of two types of wavelengths in one semiconductor chip has been developed and is becoming popular. is there. Furthermore, in order to support BD, there is a movement to combine a laser of 400 nm band (blue-violet semiconductor laser) and such a two-wavelength laser element into a three-wavelength laser device (see, for example, Patent Document 1).

  Further, with the increase in recording capacity, the recording speed has been increased, and the trend is particularly remarkable for CDs and DVDs. In order to increase the speed, it is necessary to increase the output of the semiconductor laser. In recent years, high output of over 200 to 300 mW has been demanded from the market for infrared semiconductor lasers for CDs and red semiconductor lasers for DVDs.

Hereinafter, a conventional semiconductor laser device will be described with reference to FIGS.
FIG. 8 is a configuration diagram of a conventional dual wavelength semiconductor laser device, and is a top perspective view of the conventional dual wavelength semiconductor laser 100. It is composed of two lasers, a red semiconductor laser 10 that emits laser light 15 in the 650 nm band and an infrared semiconductor laser 20 that emits laser light 25 in the 780 nm band. This laser is provided with a groove 90 in order to electrically separate the red semiconductor laser 10 and the infrared semiconductor laser 20. By individually applying a bias to the p-side electrode 30 and the n-side electrode 40, each laser can be operated individually.

  This semiconductor laser device has a front end face 50 for extracting laser light and a rear end face 60 for reflecting light into the resonator. A multilayer end face film 80 is laminated on the rear end face 60. On the other hand, an end surface coating film having a lower reflectance than that of the rear end surface 60 is formed on the front end surface 50 in order to increase the laser light extraction efficiency (see, for example, Patent Document 2).

  Further, as one effective means for increasing the output, a method of making the reflectance of the two end faces forming the resonator of the semiconductor laser asymmetric is used. This is a common method for a semiconductor laser used for writing in an optical disk device. This method is a method of making the reflectance of the end face asymmetric by coating the end face forming the resonator with a dielectric multilayer film. Of the end faces forming the resonator, the resonator on the side where the laser beam is emitted is used. The end face (front end face) has a low reflectance (about 10%) and the opposite end face (rear end face) has a high reflectance (about 90%). Note that the reflectance of the dielectric multilayer film can be controlled by the refractive index of the dielectric used, the layer thickness, and the total number of laminated layers (for example, see Non-Patent Document 1).

FIG. 9 is a diagram for explaining laser light emission in a conventional single-surface-emitting type semiconductor laser device.
As shown in FIG. 9A, light 101A emitted from an in-plane semiconductor laser 110, which is a single surface emitting semiconductor laser, is reflected by a beam steering mirror 102, and a long wavelength vertical cavity surface emitting laser 106 is reflected. To pump. Further, as shown in FIG. 9B, the electrically pumped in-plane semiconductor laser 110, vertical cavity surface emitting laser 106, and beam steering mirror 102 are monolithically formed on the substrate. The light 101A emitted from the edge-emitting type in-plane semiconductor laser 110 is reflected at an angle of 90 ° by the integrally formed beam steering mirror 102, and the vertical cavity surface emitting laser 106 is optically pumped to oscillate. The in-plane semiconductor laser 110 is configured to emit light having a relatively short wavelength, whereas the vertical cavity surface emitting laser 106 is configured to emit light having a relatively long wavelength.

In this example, the beam steering mirror 102 is used to change the light 101A emitted from the in-plane semiconductor laser 110 and the vertical cavity surface emitting laser 106 into the light 101B. The beam steering mirror 102 is used as an optical connection between the edge-emitting type in-plane semiconductor laser 110 and the vertical cavity surface emitting laser 106 (see, for example, Patent Document 3).
Japanese Patent No. 3486900 JP 2002-223030 A Special table 2003-513477 gazette JP-A-9-511147 Japanese Patent Laid-Open No. 11-161993 JP 2001-185811 A Edited by Kenichi Iga, “Semiconductor Laser”, first edition, Ohm Co., Ltd., p. 238

FIG. 10 is a diagram for explaining a part of a pickup for an optical disk using a conventional semiconductor laser device.
In FIG. 10, a beam steering mirror 303 is used to bend light 304A emitted from the two-wavelength semiconductor laser 302 by 90 degrees into light 304B. At that time, since such a mirror and a semiconductor laser element are separately formed and then mounted on one, high-precision alignment is required for each. Further, when a two-wavelength laser element is used or when a plurality of laser elements are used, there is a problem that the alignment is further complicated.

  In addition, there is a technique in which light emitted from a plurality of semiconductor lasers is reflected using a polygonal pyramid or a polyhedral mirror, and the optical axis of each laser is brought close to each other to reduce the light emitting point interval. However, such a mirror is often formed on a Si substrate, and a semiconductor laser element made of a compound semiconductor needs to be separately mounted, so that high-precision alignment is required for each (for example, Patent Documents) 4, Patent Document 5 and Patent Document 6). Furthermore, when a two-wavelength laser element is used or when a plurality of laser elements are used, there is a problem that the alignment is further complicated. For example, there are cases where the emission point interval is narrowed in laser light in three wavelength regions by mounting a two-wavelength laser semiconductor laser and a blue-violet semiconductor laser so as to overlap each other in the height direction (Patent Document 1). However, the semiconductor laser must be mounted twice, and the heat dissipation of the two-wavelength laser mounted upward as viewed from the substrate depends on the thermal conductivity of gallium nitride. Compared with (AlN or the like), the heat dissipation is reduced. Further, the optical axis of the emitted laser light is three-dimensional, and there is a problem that mounting and positioning of the mirror become very complicated.

  In addition, in a single semiconductor laser device as shown in FIG. 9, there is a technique in which light emitted from an in-plane semiconductor laser is reflected by an integrated beam steering mirror to pump a vertical cavity surface emitting laser. At this time, the beam steering mirror may be positioned as long as the light from the in-plane semiconductor laser is incident on the surface emitting laser, and its role is not used for the optical axis alignment as described above. The beam steering mirror 102 shown in FIG. 9B needs to form a low reflection mirror and a high reflection mirror on each surface of the V-shaped beam steering mirror 102, and is very difficult to manufacture in the process. There are problems (see, for example, Patent Document 2 and Patent Document 3).

  Therefore, the semiconductor laser device of the present invention has a problem of mirror alignment difficulty in a single-wavelength semiconductor laser device, and difficulty in high-precision optical axis alignment when a plurality of semiconductor lasers having different wavelengths are mixedly mounted. This improves the alignment accuracy of the mirror and reduces the radiation from each laser without reducing the heat dissipation through an easy manufacturing process. An object is to improve the positional accuracy of the optical axis with respect to laser light.

  In order to achieve the above object, a semiconductor laser device according to claim 1 of the present invention oscillates laser light by a resonator including a front mirror and a rear mirror, and refracts the oscillated laser light by a beam steering mirror. An output semiconductor laser device comprising: a substrate; a rear mirror obtained by cleaving the substrate and coating a plurality of dielectric films to increase the reflectance; and the substrate at a position facing the rear mirror of the resonator. Etch, coat at least one dielectric film and etch the substrate in the light emission direction of the resonator, and the front mirror that oscillates the laser beam with the rear mirror, and the metal film with the dielectric film A beam steering mirror for coating and refracting the laser beam emitted from the front mirror; and on the resonator And formed p-side electrode, and the p-side electrode formed on opposite positions on the n-side electrode of the resonator, and having a base for mounting the substrate.

  The semiconductor laser device according to claim 2 is the semiconductor laser device according to claim 1, wherein the resonator is a resonator of a two-wavelength semiconductor laser, and one beam steering mirror refracts emitted light having two wavelengths. It is characterized by doing.

  According to a third aspect of the present invention, in the semiconductor laser device according to the first or second aspect, the beam steering mirror is formed so that the emitted light is refracted toward the inside of the substrate. The substrate is mounted on the substrate so that the emission direction of the substrate is opposite to the connection surface with the substrate.

  A semiconductor laser device according to a fourth aspect of the present invention is the semiconductor laser device according to the first or second aspect, wherein the beam steering mirror is formed so that outgoing light is refracted to the outside of the substrate, The substrate is mounted on the substrate such that the emission direction is opposite to the connection surface with the substrate.

  The semiconductor laser device according to claim 5 is the semiconductor laser device according to claim 1 or 2, wherein the beam steering mirror is formed so that outgoing light is refracted to the outside of the substrate, A cavity is provided, and the laser beam is emitted through the cavity.

  A semiconductor laser device according to a sixth aspect of the present invention is the semiconductor laser device according to the first or second aspect, wherein the beam steering mirror is formed so that the emitted light is refracted to the outside of the substrate. The substrate is mounted with the substrate so that the emission direction is in the direction of the substrate, and the substrate has a size that does not interfere with the emitted light.

  The semiconductor laser device according to claim 7 is the semiconductor laser device according to claim 3, 4, 5, or 6, wherein the beam steering mirror is formed on the entire end face of the substrate. It is characterized by that.

  According to an eighth aspect of the present invention, in the semiconductor laser device according to the third or fourth aspect, one or more dielectric films are coated on an end surface on the beam steering mirror side in the two semiconductor laser devices, and the beam steering mirror side is coated. The end surfaces of these are abutted and mounted on a common substrate.

  A semiconductor laser device according to claim 9 is the semiconductor laser device according to claim 8, wherein one of the two semiconductor laser devices according to claim 3 or 4 has an oscillation wavelength in a wavelength of 650 nm band. A two-wavelength semiconductor laser, which is a semiconductor laser and an infrared semiconductor laser having an oscillation wavelength in a wavelength of 780 nm, and the other is a blue-violet semiconductor laser having an oscillation wavelength in a wavelength of 400 nm.

  The semiconductor laser device according to claim 10 is the semiconductor laser device according to claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 7, claim 8, or claim 9. In this semiconductor laser device, a metal film in which at least one dielectric film is inserted is used instead of the metal film.

  The semiconductor laser device according to claim 11 is the semiconductor laser device according to claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 7, claim 8, or claim 9. In the semiconductor laser device, a plurality of dielectric films are used instead of the metal film.

  As described above, it is possible to improve the mirror alignment accuracy and improve the optical axis positional accuracy with respect to the laser light emitted from each laser without reducing heat dissipation by an easy manufacturing process.

  As described above, in the semiconductor laser device of the present invention, since the resonator and the beam steering mirror are monolithically formed on the same substrate, the mirror can be aligned by a manufacturing process capable of highly accurate alignment. The mirror alignment accuracy can be improved by an easy manufacturing process without reducing heat dissipation. In addition, when mounting a plurality of monolithic semiconductor lasers, the end surfaces on which the beam steering mirrors are formed are mounted so that the intervals between the light emitting points can be formed with a highly accurate control process. Because it is determined by the position of the beam steering mirror and the film thickness of the dielectric film, the position accuracy of the optical axis with respect to the laser light emitted from each laser without reducing the heat dissipation by an easy manufacturing process And the interval between the light emitting points can be easily controlled.

  In the semiconductor laser device of the present invention, a rear mirror forming part formed by cleavage, a front mirror forming part formed by etching, and a beam steering mirror forming part inclined by etching are formed on the same substrate, and these mirrors are formed. In this configuration, a mirror is formed by coating a metal film or a dielectric multilayer film on the part, and laser light oscillated between the rear mirror and the front mirror is reflected by the beam steering mirror and emitted.

Hereinafter, embodiments of the semiconductor laser device of the present invention will be described in detail with reference to the drawings.
Example 1
1 is a cross-sectional view of a semiconductor laser device according to a first embodiment of the present invention.

  In FIG. 1, in a semiconductor laser device 401, a semiconductor laser unit 402 and a mirror unit 403, which are resonators, are integrally formed monolithically on a common substrate 301 by the same process. When the semiconductor laser device 401 is of a high output type, the base material 301 is made of a material having good heat conduction and good heat dissipation (AlN, SiC, Cu, etc.). One side (rear end surface) of the semiconductor laser unit 402 is formed by cleavage, and the laser emission surface (front end surface) conventionally formed by cleavage is etched by etching to form the mirror unit 403 on the same substrate. A mirror 405 is produced.

The front mirror 405 needs to be formed in parallel with the rear end face (cleavage face) in order to cause laser oscillation. Therefore, it is desirable to form perpendicularly to the optical axis of the laser beam by dry etching with high formation accuracy instead of wet etching. The front mirror is coated with at least one dielectric film to form a low reflectivity mirror. For example, if the wavelength of the laser light emitted from the semiconductor laser is λ, the SiO ₂ film having a refractive index of n1 is coated with a thickness of λ / (4 × n1). If λ = 650 nm and n1 = 1.48, the reflectance of the end face of the front mirror 405 can be suppressed to 10% or less. Thus, the reflectance can be controlled by the refractive index of the dielectric used for the coat film, the layer thickness, and the number of layers to be laminated. Such a low reflectance coating can reduce reflection loss when the laser light emitted from the semiconductor laser unit 402 is incident on the mirror unit 403.

The rear end face of the semiconductor laser portion 402 is formed by cleavage, and a high reflectivity rear mirror 406 is formed by a dielectric multilayer coating. In order to form a high reflectivity mirror on the rear end face, if the wavelength of the laser light emitted from the semiconductor laser is λ, the dielectric film λ / (4 × n2) having a low refractive index n2 and a dielectric having a high refractive index n3 A multilayer film composed of a pair of body films λ / (4 × n3) is required. At this time, the low refractive index material is preferably SiO ₂ , and the high refractive index material is preferably Al ₂ O ₃ , Ta ₂ O ₅ , ZrO ₂ , Nb ₂ O ₅ , TiO ₂ or the like. Hydrogenated amorphous Si (the real part of the refractive index n = 3.3) is also present as a high refractive index material, but there is a light absorption loss depending on the wavelength range, which is not preferable when considering high output. A nitride film typified by SiN is not preferable when a λ / (4 × n) film is stacked because stress acting on the semiconductor layer increases.

  Instead of using a dielectric multilayer film, a high reflectivity rear mirror can be formed by coating a metal film such as Al. In this case, it is desirable that at least one or more layers of the above-described dielectric film is inserted between the metal film to be coated and the cleavage plane formed by cleavage to prevent conduction.

  As described in Non-Patent Document 1, regardless of whether a metal film or a dielectric film is used, the reflectance of the rear mirror is a reflectance range of 80% or more at the wavelength λ of the light oscillated from the semiconductor laser. It is desirable to set to. Furthermore, by setting the reflectance range to 90% or more, the threshold current value can be reduced, and the power consumption of the device can be reduced.

  Further, a crystal plane having an inclination with respect to the optical axis is formed by etching on the substrate on the extension of the semiconductor laser unit 402 resonator. The etching method may be wet etching or dry etching. Further, wet etching may be performed after dry etching. The beam steering mirror 404 is formed by increasing the reflectivity of the tilted crystal plane with a dielectric multilayer coating. The beam steering mirror 404 reflects light from the semiconductor laser unit 402 toward the surface side (the side opposite to the base material 301).

The formation of the high reflectivity mirror in the beam steering mirror 404 is the same as the formation of the high reflectivity mirror on the rear end face. If the wavelength of the laser light emitted from the semiconductor laser is λ, it depends on a pair of a dielectric film λ / (4 × n4) with a low refractive index n4 and a dielectric film λ / (4 × n5) with a high refractive index n5. A multilayer film is required. At this time, the low refractive index material is preferably SiO ₂ , and the high refractive index material is preferably Al ₂ O ₃ , Ta ₂ O ₅ , ZrO ₂ , Nb ₂ O ₅ , TiO ₂ or the like.

  Instead of using the dielectric multilayer film, a high-reflectance beam steering mirror can be formed by coating a metal film such as Al. In this case, at least one or more layers of the above-described dielectric film may be inserted between the metal film to be coated and the cleavage plane formed by cleavage to prevent conduction.

  If the reflectivity of the beam steering mirror decreases, light leaks to the outside, resulting in a loss of light output. Regardless of whether a metal film or a dielectric film is used, it is desirable that the reflectivity of the beam steering mirror is set to a reflectivity range of 80% or more at the wavelength λ of the light emitted from the semiconductor laser. Furthermore, by setting the reflectance range to 90% or more, light leaking to the outside can be suppressed, and loss of light output can be suppressed.

  Both the p-side electrode 407 and the n-side electrode 408 are formed only on the semiconductor laser portion 402 and not on the mirror portion 403. This is because carriers (holes) are injected only into the resonator that contributes to laser oscillation so as to obtain a gain. The thus fabricated chip is junction-down mounted on the base material 301 (the junction part that generates light is on the base material side), and a bias is applied to each of the p-side electrode 407 and the n-side electrode 408 to thereby apply the semiconductor laser part 402. Can be operated. Solder used for mounting was omitted from the drawing. In the semiconductor laser unit 402, laser light oscillated between the rear mirror 406 and the front mirror 405 is incident on the mirror unit 403. When the beam steering mirror 404 is inclined by 45 ° with respect to the optical axis of the light oscillated from the semiconductor laser unit 402, the optical axis of the light oscillated from the semiconductor laser unit 402 is inclined by 90 °. The light is emitted perpendicular to the substrate. Actually, it is desirable to control the tilt of the beam steering mirror in the range of 35 ° to 55 ° in consideration of the etching process margin. Furthermore, it is more desirable to control the inclination in the range of 44 ° to 46 °.

As described above, the laser beam can be extracted from the surface through the substrate of the semiconductor laser device. The aforementioned dielectric film can be deposited by electron cyclotron resonance (ECR) sputtering, magnetron sputtering, electron beam evaporation (EB evaporation), or the like. In particular, ECR sputtering can use a high-purity metal (Si in the case of SiO ₂ ) as a target, and is suitable because a dielectric film having no light absorption can be stacked at a high deposition rate. For example, Ta ₂ O ₅ is excellent in productivity because it can be formed at a high deposition rate of about 20 nm / min by using a metal Ta target and using O ₂ as a reactive gas.

  This embodiment has been described in detail with respect to a red semiconductor laser having an oscillation wavelength in the 650 nm band, but the same applies to an infrared semiconductor laser having an oscillation wavelength in the 780 nm band and a blue-violet semiconductor laser having an oscillation wavelength in the 400 nm band. . The same applies to multi-wavelength semiconductor lasers such as dual-wavelength lasers. By optimally designing the coating material and film thickness, the front mirror 405 has a reflectance of 10% or less at each wavelength, the rear mirror 406 and the beam steering mirror. In 404, the reflectance can be 90% or more at each wavelength. In particular, by coating the rear mirror 406 and the beam steering mirror 404 with a metal film such as Al, it is possible to increase the reflectivity in a wide wavelength range, which is effective for a multi-wavelength semiconductor laser.

As described above, in the semiconductor laser device according to the first embodiment, the resonator and the beam steering mirror 404 can be easily formed by etching the front mirror 405 formation region and the beam steering mirror 404 formation region on the same substrate. Therefore, the beam steering mirror 404 can be positioned by a highly accurate process, and the positioning accuracy of the beam steering mirror 404 is improved. Furthermore, by forming a plurality of semiconductor lasers with different wavelengths monolithically on the same substrate, the position accuracy of the optical axis can be improved with respect to the laser light emitted from each laser, and the optimal emission point spacing is achieved. Can also be achieved.
(Example 2)
Various embodiments are conceivable depending on the mounting form of the semiconductor laser device and the direction in which the laser beam is extracted. Hereinafter, based on FIG. 2, the semiconductor laser device according to the second embodiment will be described in detail with a focus on differences from the first embodiment.

FIG. 2 is a cross-sectional view of the semiconductor laser device according to the second embodiment of the present invention.
As shown in FIG. 2, this semiconductor laser device 501 is also the same as that of the first embodiment in that a semiconductor laser portion 402 that is a resonator and a mirror portion 403 are integrally formed on a base material 301 in a monolithic manner. The difference is that the n-side electrode 408 is mounted on the substrate 301 side and the p-side electrode 407 is mounted on the surface side, and the junction is mounted on the substrate 301 (the junction portion for generating light is on the surface side). Solder used for mounting was omitted from the drawing.

  On the extension of the resonator in the semiconductor laser unit 402, a crystal plane having an inclination with respect to the optical axis is formed by etching or the like. The etching method may be wet etching or dry etching. Further, wet etching may be performed after dry etching. The beam steering mirror 404 is formed by increasing the reflectivity of the tilted crystal plane with a dielectric multilayer coating. The beam steering mirror 404 reflects light from the semiconductor laser unit 402 toward the surface side (the side opposite to the base material 301).

  The formation of the high reflectivity mirror in the beam steering mirror 404 is the same as the formation of the high reflectivity mirror in the first embodiment. If the reflectivity of the beam steering mirror 404 decreases, light leaks to the outside, resulting in a loss of light output. Regardless of whether a metal film or a dielectric film is used, it is desirable that the reflectivity of the beam steering mirror is set to a reflectivity range of 80% or more at the wavelength λ of the light emitted from the semiconductor laser. Furthermore, by setting the reflectance range to 90% or more, light leaking to the outside can be suppressed, and loss of light output can be suppressed.

  The semiconductor laser section 402 can be operated by applying a bias to each of the p-side electrode 407 and the n-side electrode 408. In the semiconductor laser unit 402, laser light oscillated between the rear mirror 406 and the front mirror 405 is incident on the mirror unit 403. When the beam steering mirror 404 is inclined 45 ° with respect to the optical axis of the light oscillated from the semiconductor laser unit 402, the optical axis of the light oscillated from the semiconductor laser unit 402 is inclined 90 °. Is emitted perpendicular to the substrate. Actually, it is desirable to control the tilt of the beam steering mirror in the range of 35 ° to 55 ° in consideration of the etching process margin. Furthermore, it is more desirable to control the inclination in the range of 44 ° to 46 °. Unlike the first embodiment, since the laser light does not pass through the semiconductor laser device 501, the light absorption loss generated in the substrate or the semiconductor layer can be suppressed.

As described above, the laser beam can be extracted from the surface through the substrate of the semiconductor laser device. The aforementioned dielectric film can be deposited by electron cyclotron resonance (ECR) sputtering, magnetron sputtering, electron beam evaporation (EB evaporation), or the like. Particularly ECR sputtering, (in the case of SiO ₂ Si) of high purity metal can be used to target, and the absence of light absorbing dielectric film suitable it is possible to gain a high deposition rate.

  This embodiment will be described in detail with respect to a red semiconductor laser having an oscillation wavelength in the 650 nm band, but the same applies to an infrared semiconductor laser having an oscillation wavelength in the 780 nm band and a blue-violet semiconductor laser having an oscillation wavelength in the 400 nm band. . In addition, for dual wavelength semiconductor lasers, etc., by designing the low-reflectance coat thickness and high-reflectance coat thickness optimally for both wavelengths, it is possible to handle both wavelengths by forming a single mirror surface. is there.

As described above, in the semiconductor laser device according to the second embodiment, the resonator and the beam steering mirror 404 can be easily formed by etching the front mirror 405 formation region and the beam steering mirror 404 formation region on the same substrate. Therefore, the beam steering mirror 404 can be positioned by a highly accurate process, and the positioning accuracy of the beam steering mirror 404 is improved. Furthermore, by forming a plurality of semiconductor lasers with different wavelengths monolithically on the same substrate, it is possible to improve the positional accuracy of the optical axis for the laser light emitted from each laser, and to optimize the interval between the light emitting points. Can also be achieved.
(Example 3)
Hereinafter, based on FIGS. 3 and 4, the semiconductor laser device of the third embodiment will be described in detail with a focus on differences from the first embodiment.

  FIG. 3 is a cross-sectional view of a semiconductor laser device having a cavity in a substrate according to Embodiment 3 of the present invention, and FIG. 4 is a cross-sectional view of the semiconductor laser device without a mirror portion substrate according to Embodiment 3 of the present invention.

  As shown in FIG. 3, this semiconductor laser device 601 is also the same as that of the first embodiment in that a semiconductor laser portion 402 that is a resonator and a mirror portion 403 are monolithically integrated on a base material 301. In addition, the p-side electrode 407 is set to the base material 301 side, and the junction down mounting is performed on the base material 301 (the junction part for generating light is the base material 301 side) as in the first embodiment. Solder used for mounting was omitted from the drawing.

  On the extension of the resonator in the semiconductor laser unit 402, a crystal plane having an inclination with respect to the optical axis is formed by etching or the like. The etching method may be wet etching or dry etching. Further, wet etching may be performed after dry etching. The beam steering mirror 404 is formed by increasing the reflectivity of the tilted crystal plane with a dielectric multilayer coating. The beam steering mirror 404 reflects light from the semiconductor laser unit 402 toward the substrate 301 side. At this time, a laser beam can be transmitted by forming a cavity in the base material 301 portion. Alternatively, as shown in FIG. 4, the base member 301 is configured to have only the semiconductor laser portion 402 portion that needs to be dissipated, and the mirror unit 403 has a structure in which the base member 301 is eliminated, thereby allowing laser light to pass therethrough.

  The formation of the high reflectivity mirror in the beam steering mirror 404 is the same as the formation of the high reflectivity mirror in the first embodiment. If the reflectivity of the beam steering mirror 404 decreases, light leaks to the outside, resulting in a loss of light output. Regardless of whether a metal film or a dielectric film is used, it is desirable that the reflectivity of the beam steering mirror is set to a reflectivity range of 80% or more at the wavelength λ of the light emitted from the semiconductor laser. Furthermore, by setting the reflectance range to 90% or more, light leaking to the outside can be suppressed, and loss of light output can be suppressed.

  The semiconductor laser section 402 can be operated by applying a bias to each of the p-side electrode 407 and the n-side electrode 408. In the semiconductor laser unit 402, laser light oscillated between the rear mirror 406 and the front mirror 405 is incident on the mirror unit 403. When the beam steering mirror 404 is inclined 45 ° with respect to the optical axis of the light oscillated from the semiconductor laser unit 402, the optical axis of the light oscillated from the semiconductor laser unit 402 is inclined 90 °. Is emitted perpendicular to the substrate. Actually, it is desirable to control the tilt of the beam steering mirror in the range of 35 ° to 55 ° in consideration of the etching process margin. Furthermore, it is more desirable to control the inclination in the range of 44 ° to 46 °.

  In this manner, heat dissipation can be ensured by mounting the junction that generates light and generates a large amount of heat on the substrate 301 side. In addition, by providing a cavity in the laser beam passage region of the substrate or forming a mirror part outside the substrate, it is not necessary for the laser beam to pass through the semiconductor laser device 601 and the semiconductor laser device 701. Light absorption loss in the substrate or semiconductor layer can be suppressed.

As described above, the laser light can be extracted through the base material of the semiconductor laser device. The aforementioned dielectric film can be deposited by electron cyclotron resonance (ECR) sputtering, magnetron sputtering, electron beam evaporation (EB evaporation), or the like. In particular, ECR sputtering is suitable because a high-purity metal (Si in the case of SiO ₂ ) can be used as a target, and a dielectric film without light absorption can be stacked at a high deposition rate.

  This embodiment will be described in detail with respect to a red semiconductor laser having an oscillation wavelength in the 650 nm band, but the same applies to an infrared semiconductor laser having an oscillation wavelength in the 780 nm band and a blue-violet semiconductor laser having an oscillation wavelength in the 400 nm band. . In addition, for dual wavelength semiconductor lasers, etc., by designing the low-reflectance coat thickness and high-reflectance coat thickness optimally for both wavelengths, it is possible to handle both wavelengths by forming a single mirror surface. is there.

As described above, in the semiconductor laser device according to the third embodiment, the resonator and the beam steering mirror 404 can be easily formed by etching the front mirror 405 formation region and the beam steering mirror 404 formation region on the same substrate. Therefore, the beam steering mirror 404 can be positioned by a highly accurate process, and the positioning accuracy of the beam steering mirror 404 is improved. In addition, by forming a plurality of semiconductor lasers with different wavelengths monolithically on the same substrate, the position accuracy of the optical axis can be improved with respect to the laser light emitted from each laser, and the light emitting point interval can be optimized. Can also be achieved. Furthermore, heat dissipation can be ensured by mounting the junction with the substrate 301 side.
Example 4
Hereinafter, based on FIG. 5, the semiconductor laser device of the fourth embodiment will be described in detail with a focus on differences from the first to third embodiments.

FIG. 5 is a cross-sectional view of a semiconductor laser device according to Embodiment 4 of the present invention.
As shown in FIG. 5, this semiconductor laser device 801 is also the same as that of the first embodiment in that the semiconductor laser portion 402 and the mirror portion 403 are integrally formed on the base member 301 in a monolithic manner.

  On the extension of the resonator in the semiconductor laser unit 402, a crystal plane having an inclination with respect to the optical axis is formed by etching or the like. The difference from the first to third embodiments is that the inclined surface extends over the entire end surface on one side of the semiconductor laser device 801. The formation method may be wet etching or dry etching. Further, wet etching may be performed after dry etching. In the case of this structure, in order to produce an inclined surface on the entire end surface, a polishing process for obtaining a mirror surface may be combined. Etching may be performed after polishing. The beam steering mirror 404 is formed by increasing the reflectivity of the crystal plane with the entire end face inclined by applying a dielectric multilayer coating. The beam steering mirror 404 reflects the light from the semiconductor laser unit 402 toward the surface side (the side opposite to the base material 301). The formation of the high reflectivity mirror in the beam steering mirror 404 is the same as the formation of the high reflectivity mirror in the first embodiment. If the reflectivity of the beam steering mirror 404 decreases, light leaks to the outside, resulting in a loss of light output. Regardless of whether a metal film or a dielectric film is used, it is desirable that the reflectivity of the beam steering mirror is set to a reflectivity range of 80% or more at the wavelength λ of the light emitted from the semiconductor laser. Furthermore, by setting the reflectance range to 90% or more, light leaking to the outside can be suppressed, and loss of light output can be suppressed.

  The semiconductor laser section 402 can be operated by applying a bias to each of the p-side electrode 407 and the n-side electrode 408. In the semiconductor laser unit 402, laser light oscillated between the rear mirror 406 and the front mirror 405 is incident on the mirror unit 403. When the beam steering mirror 404 is inclined by 45 ° with respect to the optical axis of the light oscillated from the semiconductor laser unit 402, the optical axis of the light oscillated from the semiconductor laser unit 402 is inclined by 90 °. Is emitted perpendicular to the substrate. In practice, it is desirable to control the tilt of the beam steering mirror in the range of 35 ° to 55 ° in consideration of the process margin of the etching and polishing processes. Furthermore, it is more desirable to control the inclination in the range of 44 ° to 46 °.

As described above, the laser beam can be extracted from the surface through the substrate of the semiconductor laser device. The aforementioned dielectric film can be deposited by electron cyclotron resonance (ECR) sputtering, magnetron sputtering, electron beam evaporation (EB evaporation), or the like. In particular, ECR sputtering is suitable because a high-purity metal (Si in the case of SiO ₂ ) can be used as a target, and a dielectric film without light absorption can be stacked at a high deposition rate.

  This embodiment will be described in detail with respect to a red semiconductor laser having an oscillation wavelength in the 650 nm band, but the same applies to an infrared semiconductor laser having an oscillation wavelength in the 780 nm band and a blue-violet semiconductor laser having an oscillation wavelength in the 400 nm band. . In addition, for dual wavelength semiconductor lasers, etc., by designing the low-reflectance coat thickness and high-reflectance coat thickness optimally for both wavelengths, it is possible to handle both wavelengths by forming a single mirror surface. is there.

As described above, in the semiconductor laser device according to the fourth embodiment, the resonator and the beam steering mirror 404 can be easily formed by etching the front mirror 405 formation region and the beam steering mirror 404 formation region on the same substrate. Therefore, the beam steering mirror 404 can be positioned by a highly accurate process, and the positioning accuracy of the beam steering mirror 404 is improved. Furthermore, by forming a plurality of semiconductor lasers with different wavelengths monolithically on the same substrate, it is possible to improve the positional accuracy of the optical axis for the laser light emitted from each laser, and to optimize the interval between the light emitting points. Can also be achieved.
(Example 5)
Next, a semiconductor laser device in which a plurality of semiconductor lasers are mixed will be described with reference to the examples shown in FIGS.

  FIG. 6 is a cross-sectional view of a semiconductor laser device with junction-down mounting in Example 5 of the present invention, which is a combination of the semiconductor laser device in Example 1 (see FIG. 1). FIG. 7 is a cross-sectional view of a semiconductor laser device with junction-up mounting according to the fifth embodiment of the present invention, which is a combination of the semiconductor laser devices according to the second embodiment (see FIG. 2). Hereinafter, the semiconductor laser device of the present invention will be described in detail with reference to FIG.

  The structure of a conventional two-wavelength semiconductor laser is shown in Patent Document 2 and FIG. In the present invention, in the two-wavelength semiconductor laser, the oscillation wavelength of one semiconductor laser is different from the oscillation wavelength of the other semiconductor laser. For example, one semiconductor laser can be a red semiconductor laser that emits laser light in the 650 nm band, and the other semiconductor laser can be an infrared semiconductor laser that emits laser light in the 780 nm band. In the case of a dual wavelength semiconductor laser, both the low reflectance coat and the high reflectance coat must be formed so as to have a desired reflectance in each wavelength region. The reflectance can be controlled by the refractive index of the dielectric, the layer thickness, and the number of layers stacked. Considering this point, the red / infrared dual-wavelength semiconductor laser device 1001 and the blue-violet semiconductor laser device 1002 are individually manufactured in the same manner as in the second embodiment. The two-wavelength semiconductor laser device 1001 is obtained by monolithically forming red and infrared resonators and a common beam steering mirror on a single substrate.

For the two-wavelength semiconductor laser device 1001 or the blue-violet semiconductor laser device 1002, at least one dielectric film 919 is formed on the end surface on the side where the beam steering mirror is to be formed (the side opposite to the rear mirror 909 and the rear mirror 916). If necessary, a dielectric film 919 may be formed on both the end face of the two-wavelength semiconductor laser device 1001 and the end face of the blue-violet semiconductor laser device 1002. This dielectric film 919 insulates between the two-wavelength semiconductor laser device 1001 and the blue-violet semiconductor laser device 1002 and is used as a buffer layer at the time of mounting, so that SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , ZrO ₂ , There is no particular limitation as long as it is a dielectric (insulator) film such as Nb ₂ O ₅ or TiO ₂ .

  The two-wavelength semiconductor laser device 1001 and the blue-violet semiconductor laser device 1002 are mounted on the base material 301 so that the n-side electrode 912, the n-side electrode 913, and the n-side electrode 918 are on the base material 301 side. At this time, the end surfaces on which the beam steering mirrors of each chip are formed are abutted and mounted so as to sandwich the dielectric film 919 formed in advance. That is, the beam steering mirror 907 and the end surface on the beam steering mirror 914 side (the opposite side of the rear mirror 909 and the rear mirror 916) are brought into contact with each other. As a result, the distance between the light emitting points of the two-wavelength semiconductor laser device 1001 and the blue-violet semiconductor laser device 1002 can be simplified by adding the distance between the beam steering mirror and the end surface and the thickness of the dielectric film 919 with high formation position accuracy by the manufacturing process. I want to. That is, either one of the two-wavelength semiconductor laser device 1001 or the blue-violet semiconductor laser device 1002 is mounted in advance, and then the other is mounted by butting, thereby realizing simple mounting and reducing the light emitting point interval. It can be controlled with good reproducibility. Moreover, it becomes possible to narrow the light emission point interval of each laser.

  By applying a bias to each of the p-side electrode 910, the p-side electrode 911, the n-side electrode 912, and the n-side electrode 913, the two-wavelength semiconductor laser unit 903 can be operated. Similarly, the blue-violet semiconductor laser portion 905 can be operated by applying a bias to the p-side electrode 917 and the n-side electrode 918. Laser light oscillated in the semiconductor laser unit 903 and the semiconductor laser unit 905 enters the mirror unit 904 and the mirror unit 906, respectively. When the beam steering mirror 907 and the beam steering mirror 914 are inclined at 45 ° with respect to the optical axis of the light oscillated from the semiconductor laser unit 903 and the semiconductor laser unit 905, the oscillation from the semiconductor laser unit 903 and the semiconductor laser unit 905 is performed. The optical axis of the emitted light is inclined by 90 °, and the laser light is emitted perpendicular to the substrate 301. Actually, it is desirable to control the tilt of the beam steering mirror in the range of 35 ° to 55 ° in consideration of the etching process margin. Furthermore, it is more desirable to control the inclination in the range of 44 ° to 46 °.

The aforementioned dielectric film can be deposited by electron cyclotron resonance (ECR) sputtering, magnetron sputtering, electron beam evaporation (EB evaporation), or the like. In particular, ECR sputtering can use a high-purity metal (Si in the case of SiO ₂ ) as a target, and is suitable because a dielectric film having no light absorption can be stacked at a high deposition rate.

  According to the semiconductor laser device of the present embodiment, the two-wavelength (red / infrared) semiconductor laser and the blue-violet semiconductor laser having the configurations shown in the first to fourth embodiments are mounted with the end surfaces on which the beam steering mirrors are formed facing each other. Therefore, the distance between the light emitting points is determined by the position of the steering mirror and the film thickness of the dielectric film formed by a highly accurate controllable manufacturing process. A laser can be realized. Further, since each semiconductor laser is directly mounted on the base material, there is a great advantage in terms of ease of mounting and heat dissipation compared to the case where both semiconductor lasers are stacked in the height direction.

  The present invention can improve the alignment accuracy of the mirror without reducing heat dissipation by an easy manufacturing process, and can improve the accuracy of the optical axis for the laser light emitted from each laser, This is useful for a semiconductor laser device or the like on which a plurality of light sources used mainly for optical disk light sources are mounted.

Sectional drawing of the semiconductor laser apparatus in Example 1 of this invention Sectional drawing of the semiconductor laser apparatus in Example 2 of this invention Sectional drawing of the semiconductor laser apparatus which has a cavity in the board | substrate in Example 3 of this invention Sectional drawing of the semiconductor laser apparatus which eliminated the board | substrate of the mirror part in Example 3 of this invention Sectional drawing of the semiconductor laser apparatus in Example 4 of this invention Sectional drawing of the semiconductor laser apparatus which carried out the junction down mounting in Example 5 of this invention Sectional drawing of the semiconductor laser apparatus which carried out the junction up mounting in Example 5 of this invention Configuration diagram of a conventional dual wavelength semiconductor laser device The figure explaining the laser emission in the conventional single surface emitting semiconductor laser device The figure explaining a part of pick-up of the optical disk using the conventional semiconductor laser apparatus

Explanation of symbols

10 Red semiconductor laser (650nm MQW)
15 Laser light 20 Infrared semiconductor laser (780 nm MQW)
25 Laser light 30 Electrode 40 Electrode 50 Front end face 60 Rear end face 80 Multilayer end face film 90 Groove 100 Dual wavelength semiconductor laser 101A Light 101B Light 102 Beam steering mirror 106 Vertical cavity surface emitting laser 110 In-plane semiconductor laser 301 Substrate 302 Dual wavelength semiconductor Laser 303 Beam steering mirror 304A Light 304B Light 401 Semiconductor laser device 402 Semiconductor laser unit 403 Mirror unit 404 Beam steering mirror 405 Front mirror 406 Rear mirror 407 P-side electrode 408 N-side electrode 501 Semiconductor laser device 601 Semiconductor laser device 701 Semiconductor laser device 801 Semiconductor laser device 903 Laser unit 904 Mirror unit 905 Laser unit 906 Mirror unit 907 Beam steering mirror 909 Amirror 910 p-side electrode 911 p-side electrode 912 n-side electrode 913 n-side electrode 914 beam steering mirror 916 rear mirror 917 p-side electrode 918 n-side electrode 919 dielectric film 1001 two-wavelength semiconductor laser device 1002 blue-violet semiconductor laser device

Claims (11)

A semiconductor laser device that oscillates laser light with a resonator including a front mirror and a rear mirror, and refracts and outputs the oscillated laser light with a beam steering mirror,
A substrate,
Cleaving the substrate and coating a plurality of dielectric films to increase the reflectivity; and
A front mirror that etches the substrate at a position facing the rear mirror of the resonator, coats at least one dielectric film, and oscillates laser light with the rear mirror;
A beam steering mirror that etches the substrate in the light emitting direction of the resonator, coats a metal film, and refracts and outputs laser light emitted from the front mirror;
A p-side electrode formed on the resonator;
An n-side electrode formed at a position facing the p-side electrode of the resonator;
A semiconductor laser device comprising: a base material on which the substrate is mounted.   2. The semiconductor laser device according to claim 1, wherein the resonator is a resonator of a two-wavelength semiconductor laser, and refracts outgoing light having two wavelengths by one beam steering mirror.   The beam steering mirror is formed so that the emitted light is refracted in the direction of the inside of the substrate, and the substrate is mounted on the substrate so that the emission direction of the laser beam is opposite to the connection surface with the substrate. The semiconductor laser device according to claim 1, wherein:   The beam steering mirror is formed so that the emitted light is refracted to the outside of the substrate, and the substrate is mounted on the substrate so that the emission direction of the laser beam is opposite to the connection surface with the substrate. 3. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is characterized in that   3. The beam steering mirror according to claim 1, wherein the beam steering mirror is formed so that outgoing light is refracted to the outside of the substrate, a cavity is provided in the base material, and the laser light is emitted through the cavity. The semiconductor laser device according to any one of the above.   The beam steering mirror is formed so that the emitted light is refracted to the outside of the substrate, the substrate is mounted on the substrate so that the emission direction of the laser light is in the direction of the substrate, and the substrate is 3. The semiconductor laser device according to claim 1, wherein the semiconductor laser device has a size that does not interfere with incident light.   The semiconductor laser device according to claim 3, wherein the beam steering mirror is formed on the entire end face of the substrate.   5. The semiconductor laser device according to claim 3, wherein the end surface on the beam steering mirror side is coated with one or more dielectric films, and the end surface on the beam steering mirror side is abutted to form a common base material A semiconductor laser device mounted on the semiconductor laser device.   5. A two-wavelength semiconductor laser in which one of the two semiconductor laser devices according to claim 3 or 4 is a red semiconductor laser having an oscillation wavelength in the wavelength 650 nm band and an infrared semiconductor laser having an oscillation wavelength in the wavelength 780 nm band. 9. The semiconductor laser device according to claim 8, wherein the other is a blue-violet semiconductor laser having an oscillation wavelength in a wavelength band of 400 nm.  A metal film in which at least one dielectric film is inserted is used in place of the metal film. The claim 1, 2 or 3, or 4 or 5 or 6 or The semiconductor laser device according to claim 7, claim 8, or claim 9.   A multi-layered dielectric film is used in place of the metal film. The claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 or claim 7 or claim 8. A semiconductor laser device according to claim 9.

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