JP2018152467A - Surface-emitting laser element, surface-emitting laser array element, light source unit, laser device, and ignition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-emitting laser element having high output.SOLUTION: This surface emitting laser element includes a first reflection mirror and a second reflecting mirror which are formed so as to sandwich an active layer, a first electrode connected to the first reflecting mirror, and a second electrode connected to the second reflecting mirror, and emits laser beams from the second reflecting mirror side. The first electrode includes: a first region formed by a first material for forming a semiconductor material and an ohmic contact constituting the first reflecting mirror; and a second region formed by a second material whose thermal-conductivity is higher than that of the first material. The first region and the second region are in contact with the first reflecting mirror.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface emitting laser element, a surface emitting laser array element, a light source unit, a laser device, and an ignition device.

  A surface emitting laser element (VCSEL: Vertical Cavity Surface Emitting LASER) is a semiconductor laser that emits light in a direction perpendicular to a substrate surface. In a surface emitting laser element, a pair of opposing high-reflectivity mirrors are provided, and a resonator structure including an active layer is provided between the pair of reflectors. The resonator structure has, for example, a configuration in which spacer layers are provided above and below the active layer.

  A surface-emitting laser element has a feature that, in principle, mode hops do not occur and wavelength stability is excellent. On the other hand, since the surface emitting laser element has a structure in which the active layer is sandwiched between the reflecting mirrors, it is difficult to dissipate heat and is not suitable for high output. Accordingly, in order to achieve high output in the surface emitting laser element, it is necessary to expand the injection area, improve the heat dissipation characteristics, and the like.

  In a surface emitting laser element, as a technique for enlarging while controlling the injection area, for example, a technique has been proposed in which laser light is emitted on the n side and the injection region is controlled by the shape of the p side electrode (for example, non-patent document 1 and 2).

  However, the above technique has not sufficiently improved the heat dissipation characteristics, so that a sufficiently high output has not been obtained.

  The present invention has been made in view of the above, and an object of the present invention is to provide a high-power surface emitting laser element.

  The surface emitting laser element includes a first reflecting mirror and a second reflecting mirror formed so as to sandwich an active layer, a first electrode connected to the first reflecting mirror, and the second reflecting mirror. A surface-emitting laser element that emits laser light from the second reflecting mirror side, wherein the first electrode includes the first reflecting mirror. A first region formed of a first material that forms an ohmic contact with a semiconductor material to constitute; a second region formed of a second material having a higher thermal conductivity than the first material; And the first region and the second region are in contact with the first reflecting mirror.

  According to the disclosed technology, a high-power surface emitting laser element can be provided.

It is a figure which illustrates the surface emitting laser element which concerns on 1st Embodiment. It is a bottom view illustrating the surface emitting laser element according to the first embodiment. 1 is a plan view illustrating a surface emitting laser element according to a first embodiment. 6 is a cross-sectional view illustrating a surface emitting laser element according to Comparative Example 1. FIG. 6 is a cross-sectional view illustrating a surface emitting laser element according to Comparative Example 2. FIG. It is a schematic block diagram which illustrates the laser apparatus which concerns on 2nd Embodiment. It is a schematic block diagram which illustrates the ignition device which concerns on 3rd Embodiment. It is a figure explaining the laser resonator of the ignition device shown in FIG.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<First Embodiment>
1A and 1B are diagrams illustrating a surface emitting laser element according to a first embodiment. FIG. 1A is a cross-sectional view, and FIG. 1B is a partially enlarged cross section of a portion A in FIG. FIG. FIG. 2 is a bottom view illustrating the surface emitting laser element according to the first embodiment. FIG. 3 is a plan view illustrating the surface emitting laser element according to the first embodiment.

  Referring to FIG. 1, a surface emitting laser element 100 is, for example, a vertical cavity laser element having an oscillation wavelength of 1064 nm band. However, the oscillation wavelength shown here is an example, and the oscillation wavelength may be, for example, the 808 nm band, the 780 nm band, or the like.

  The surface emitting laser element 100 includes a first reflecting mirror 110, a resonator structure 120 (a lower spacer layer 121, an active layer 122, and an upper spacer layer 123), a second reflecting mirror 130, and a first electrode 140. And an insulating film 150 and a second electrode 160. The surface emitting laser element 100 may have other components as necessary. Examples of other components include a buffer layer and a contact layer.

  In the surface emitting laser element 100, the semiconductor layer can be formed by, for example, a metal organic chemical vapor deposition (MOCVD) method, a molecular beam epitaxy (MBE) method, or the like. .

  The surface emitting laser element 100 can be mounted on the heat sink 200 via, for example, AuSn solder. When the surface emitting laser element 100 is mounted on the heat sink 200, the heat generated in the active layer 122 of the surface emitting laser element 100 is released from the heat sink 200 to the outside through the first electrode 140.

  Hereinafter, the surface emitting laser element 100 will be described in detail. In the present embodiment, for convenience, the second electrode 160 side of the surface emitting laser element 100 is referred to as a front side or an upper side, and the first electrode 140 side is referred to as a back side or a lower side. Further, the surface on the second electrode 160 side of each part is referred to as a front surface or an upper surface, and the surface on the first electrode 140 side is referred to as a back surface or a lower surface. However, the surface emitting laser element 100 can be used upside down, or can be arranged at an arbitrary angle. In addition, the shape of each component of the surface emitting laser element 100 viewed from the light emission direction may be referred to as a planar shape. In addition, a direction perpendicular to the stacking direction (thickness direction) of each component of the surface emitting laser element 100 may be referred to as a plane direction.

  In the surface emitting laser element 100, a first reflecting mirror 110 which is a p-type semiconductor and a second reflecting mirror 130 which is an n-type semiconductor are formed so as to sandwich the active layer 122. The first reflecting mirror 110 is also called a lower DBR (Distributed Bragg Reflector). For example, a pair of a low refractive index layer made of C-doped p-GaAs and a high refractive index layer made of C-doped p-AlAs. 30 pairs. The thickness of the first reflecting mirror 110 is adjusted to an optical thickness of one wavelength (for example, 1064 nm).

  In the first reflecting mirror 110, a composition gradient layer in which the composition is gradually changed from one composition to the other composition may be provided between the low refractive index layer and the high refractive index layer. By providing the composition gradient layer, the electrical resistance can be reduced. The low-refractive index layer and the high-refractive index layer can be designed to include ½ of the film thickness of the adjacent composition gradient layer and have an optical thickness of λ / 4 with respect to the oscillation wavelength λ. When the optical thickness is λ / 4, the actual film thickness D of the layer is D = λ / 4n (where n is the refractive index of the medium of the layer).

  The resonator structure 120 is stacked on the upper surface of the first reflecting mirror 110. The resonator structure 120 has a structure in which a lower spacer layer 121, an active layer 122, and an upper spacer layer 123 are stacked from the first reflecting mirror 110 side. The lower spacer layer 121 and the upper spacer layer 123 can be formed of, for example, GaAs.

  The active layer 122 has, for example, a triple quantum well (TQW) in which three GaInAs layers 122a having a thickness of about 5 nm and two GaAs layers 122b having a thickness of about 8 nm are alternately stacked. ing. However, the active layer 122 may have a multi quantum well (MQW) structure other than the triple quantum well structure.

  When the surface emitting laser element 100 has an oscillation wavelength of 1064 nm, the oscillation wavelength of the GaInAs layer 122a is adjusted to, for example, 1054 nm, and the thickness T of the resonator structure 120 is an optical thickness of one wavelength (1064 nm). It has been adjusted.

  The second reflecting mirror 130 is stacked on the upper spacer layer 123. The second reflecting mirror 130 is also called an upper DBR, and has, for example, 22 pairs of a low refractive index layer made of Si-doped n-GaAs and a high refractive index layer made of Si-doped n-AlAs. ing. The thickness of the second reflecting mirror 130 is adjusted to an optical thickness of one wavelength (for example, 1064 nm).

  In the second reflecting mirror 130, a composition gradient layer in which the composition is gradually changed from one composition to the other composition may be provided between the low refractive index layer and the high refractive index layer. By providing the composition gradient layer, the electrical resistance can be reduced. The low-refractive index layer and the high-refractive index layer can be designed to include ½ of the film thickness of the adjacent composition gradient layer and have an optical thickness of λ / 4 with respect to the oscillation wavelength λ.

  A current confinement layer may be provided in one of the low refractive index layers in the second reflecting mirror 130. The current confinement layer may be configured to include, for example, an oxidized selective oxidation region and an unoxidized current passing region. The selective oxidation region can be formed by oxidizing the current confinement layer from the side surface side.

  The first electrode 140 is formed in contact with the lower surface of the first reflecting mirror 110 (the surface opposite to the laser light emission side) and is electrically connected to the first reflecting mirror 110. As shown in FIG. 2A, the planar shape of the first electrode 140 may be, for example, a circle, but is not limited thereto, and may be an ellipse, a rectangle, a polygon, or any other shape. Can do.

An insulating film 150 that is in contact with the lower surface of the first reflecting mirror 110 is provided around the first electrode 140. As a material of the insulating film 150, for example, a silicon nitride film (SiN film), a silicon oxide film (SiO ₂ film), a silicon oxynitride film (SiON film), or the like can be used. For example, the lower surface of the first electrode 140 and the lower surface of the insulating film 150 can be flush with each other.

  As shown in FIG. 2B, the first electrode 140 includes a first region 141 in which a plurality of mutually spaced through holes 141x penetrating in the thickness direction are formed, and each of the through holes 141x. A second region 142 to be filled is formed. The first region 141 is formed from a first material, and the second region 142 is formed from a second material different from the first material.

  As a first material for forming the first region 141, a semiconductor material that forms an ohmic contact with the semiconductor material forming the first reflecting mirror 110 can be selected. The first region 141 can be, for example, a single layer film. In this case, the single layer film may be formed of a single material or an alloy of two or more materials. The first region 141 may be a stacked film in which different materials are stacked.

  Generally, the thermal resistance of a material is said to be higher as the number of constituent elements is smaller. By selecting such a material, the heat radiation characteristics of the surface emitting laser element 100 can be improved.

  For example, when the material of the layer in contact with the first electrode 140 in the first reflecting mirror 110 is GaAs, for example, AuZn that is a binary alloy can be used as the first material. Alternatively, an AuZn / Au laminated film in which an AuZn film and an Au film are sequentially laminated from the first reflecting mirror 110 side may be used as the first material.

  As the second material, a material having a higher thermal conductivity than the first material can be selected. In the case where the first material is an AuZn film or an AuZn / Au laminated film, for example, Ag or the like can be used as the second material.

  In order to form the first electrode 140, for example, first, the first region 141 is formed larger than the final shape on the lower surface of the first reflecting mirror 110 by vapor deposition, sputtering, plating, or the like. Thereafter, the first region 141 is patterned by lift-off, etching, or the like. By patterning, for example, the first region 141 that is circular as a whole and includes a plurality of through holes 141x is formed. If necessary, the first material forming the first region 141 is annealed and alloyed to obtain ohmic contact with the first reflecting mirror 110.

  Next, the second region 142 is formed by filling each through hole 141x with a second material by vapor deposition, sputtering, plating, or the like. The second region 142 only needs to be in physical contact with the first reflecting mirror 110 and does not need to form an ohmic contact.

  The second electrode 160 is formed in contact with the upper surface (the surface on the laser beam emission side) of the second reflecting mirror 130 and is electrically connected to the second reflecting mirror 130. The second electrode 160 forms an ohmic contact with the second reflecting mirror 130. As shown in FIG. 3, the planar shape of the second electrode 160 may be annular. However, the planar shape of the second electrode 160 is not limited to an annular shape in which a part of a circle is opened. For example, an annular shape in which a part of an ellipse is opened, an annular shape in which a part of a rectangle is opened, and many An annular shape in which a part of the square shape is opened, and an annular shape in which a part of any other shape is opened.

  The second electrode 160 can be, for example, a single layer film. In this case, the single layer film may be formed of a single material or an alloy of two or more materials. The second electrode 160 may be a stacked film in which different materials are stacked.

  For example, when the material of the layer in contact with the second electrode 160 in the second reflecting mirror 130 is GaAs, the material of the second electrode 160 can be, for example, AuGe that is a binary alloy. . Alternatively, as the material of the second electrode 160, an AuGe / Au laminated film in which an AuGe film and an Au film are sequentially laminated from the second reflecting mirror 130 side may be used. The second electrode 160 can be formed by, for example, vapor deposition, sputtering, plating, or the like.

  The first electrode 140 is preferably formed inside the opening of the second electrode 160 when viewed from the normal direction of the upper surface (the surface on the laser beam emission side) of the second reflecting mirror 130. The light emission region of the surface emitting laser element 100 is substantially determined by the shape of the opening of the second electrode 160, and the current injection region is substantially determined by the shape of the first electrode 140. Therefore, there is no problem if the first electrode 140 is formed outside the opening of the second electrode 160, but the efficiency of current injection is reduced.

  When the first electrode 140 and the second electrode 160 of the surface emitting laser element 100 are connected to the voltage applying means, p-type carriers (holes) injected from the first electrode 140 and the second electrode 160 are injected. The n-type carriers (electrons) are diffused and uniformly injected into the active layer 122. As a result, carriers reach an inversion distribution inside the active layer 122, and laser light is emitted from the opening of the annular second electrode 160 in the direction of arrow L in FIG.

  As described above, the surface emitting laser element 100 exhibits a function as a light emitting device by carrier injection into the active layer 122. Carriers to be injected are holes and electrons, and these carriers have a certain mobility depending on temperature and conductive material. However, there is a difference of about 1000 times in mobility between the two, and holes have a much lower mobility than electrons.

  Therefore, in the surface emitting laser element 100, the first reflecting mirror 110 is formed of a p-type semiconductor, and the second reflecting mirror 130 is formed of an n-type semiconductor. A p-type carrier and an n-type carrier are injected from the first electrode 140 and the second electrode 160, respectively, and light emission is recombined in the active layer 122 to realize laser oscillation.

  At this time, holes, which are p-type carriers injected from the first electrode 140, have a low mobility, and thus are in a direction parallel to the first reflecting mirror 110 and the second reflecting mirror 130. Does not diffuse so much and reaches the active layer 122.

  The diffusion of holes that are p-type carriers in the direction parallel to the first reflecting mirror 110 and the second reflecting mirror 130 depends on the thickness and resistance of the first reflecting mirror 110. For example, When the thickness of the reflecting mirror 110 is about 4 μm, it diffuses about 5 μm while conducting about 4 μm.

  On the other hand, since electrons injected from the second electrode 160 have high mobility, they are diffused in the direction parallel to the first reflecting mirror 110 and the second reflecting mirror 130 and reach the active layer 122. By using the first reflecting mirror 110 as a p-type semiconductor and injecting holes from the first electrode 140, carriers can be injected into the active layer 122 at a high current density.

  Note that in the first electrode 140, the second material gives priority to heat dissipation characteristics, and ohmic contact with the semiconductor material of the first reflecting mirror 110 is not ensured. Not injected. Therefore, in order to uniformly inject current into the active layer 122, it is necessary to limit the size of the second region 142. For example, when the second region 142 is circular, the diameter is preferably 10 μm or less. By uniformly injecting current into the active layer 122, the surface emitting laser element 100 having a uniform beam intensity and a controlled beam shape can be realized.

  As described above, in the surface emitting laser element 100, the second electrode 160 is annular, and the current injection region is controlled by the first electrode 140, thereby realizing uniform carrier injection over a large area and high output. Is possible.

  In addition, the surface emitting laser element 100 has improved heat dissipation characteristics and higher output than the conventional surface emitting laser element. This will be described with reference to FIGS.

  FIG. 4 is a cross-sectional view illustrating a surface emitting laser element according to Comparative Example 1. The surface emitting laser element 100x according to Comparative Example 1 is a surface emitting laser element in which the current injection region is not enlarged. In the surface emitting laser element 100x, the first electrode 140x is formed only of the first material that forms an ohmic contact with the semiconductor material constituting the first reflecting mirror 110.

  In the surface emitting laser element 100x, heat generated by carrier injection into the active layer 122 is released from the heat sink 200 to the outside. In the case of the surface emitting laser element 100x, since the opposite side of the heat sink 200 is an emission surface, it is difficult to effectively dissipate heat. Therefore, as shown in FIG. 4, heat is released to the heat sink 200 through a path (path indicated by an arrow) that bypasses the active layer 122 that is a heat generation source.

  FIG. 5 is a cross-sectional view illustrating a surface emitting laser element according to Comparative Example 2. The surface emitting laser element 100y according to Comparative Example 2 is a surface emitting laser element in which a current injection region is enlarged. In the surface emitting laser element 100y, the first electrode 140y is formed only of the first material that forms an ohmic contact with the semiconductor material forming the first reflecting mirror 110.

  In the surface emitting laser element 100y, the heat generated in the peripheral portion of the active layer 122 is released from the heat sink 200 as in the case of FIG. On the other hand, it is clear from thermal simulation that heat (B part) generated near the center of the active layer 122 becomes difficult to be released to the outside due to heat generation in the peripheral part.

  That is, when considering increasing the output of the surface emitting laser element, it is not sufficient to simply enlarge the current injection area, and it is necessary to improve the heat dissipation characteristics. Specifically, since the heat dissipation path is only under the active layer 122, the thermal resistance under the active layer 122 must be reduced.

  Therefore, in the surface emitting laser element 100, the first electrode 140 has a higher thermal conductivity than the first material and the first material that forms an ohmic contact with the semiconductor material forming the first reflecting mirror 110. It is made of the second material.

  Thereby, it is possible to connect to the semiconductor material forming the first reflecting mirror 110 with low resistance, and in addition to the case where the first electrode 140 is formed only from the first material, the heat below the active layer 122 is reduced. Resistance can be reduced and heat dissipation characteristics can be improved. As a result of improving the heat dissipation characteristics, the surface emitting laser element 100 can further increase the output as compared with the case where the first electrode 140 is formed of only the first material.

  That is, the electrode material that forms an ohmic contact with the semiconductor material is limited, and not all materials satisfy the conditions. On the other hand, when an electrode is used as a heat dissipation member, higher thermal conductivity is preferable, but such a material does not necessarily form an ohmic contact with a semiconductor material.

  Therefore, in the present embodiment, the first electrode 140 is made of a first material that forms an ohmic contact with the semiconductor material that forms the first reflecting mirror 110, and the first material that has higher thermal conductivity than the first material. By combining the two materials, the semiconductor material constituting the first reflecting mirror 110 can be connected with low resistance, and the first electrode 140 is formed using only the first material. Thus, the surface emitting laser element 100 with improved heat dissipation characteristics is realized. As a result of improving the heat dissipation characteristics, the surface emitting laser element 100 can achieve higher output as compared with the case where the first electrode 140 is formed of only the first material (in the case of FIG. 5 and the like). .

  In the above description, the first electrode 140 is formed of the first material that forms an ohmic contact with the semiconductor material forming the first reflecting mirror 110, and the second material has a higher thermal conductivity than the first material. As an example of forming in combination with this material, an example is shown in which the second region 142 is formed by filling a plurality of substantially circular through holes 141x formed in the first region 141 with the second material ( (Refer FIG.2 (b)).

  However, the shape and arrangement of the first region 141 and the second region 142 constituting the first electrode 140 are not limited to the example of FIG. For example, the through hole 141x of the first region 141 may be formed in a stripe shape or a slit shape, and each through hole 141x may be filled with the second material to form the second region 142. Alternatively, the shape of the through hole 141x may be other than these. Note that, regardless of the shape of the through-hole 141x, it is necessary to limit the size of the second region 142 in order to uniformly inject current into the active layer 122 as described above.

<Second Embodiment>
In the second embodiment, an example of a light source unit and a laser apparatus having the surface emitting laser element according to the first embodiment will be described. In the second embodiment, description of the same components as those of the already described embodiments may be omitted.

  FIG. 6 is a schematic configuration diagram illustrating a laser device according to the second embodiment. As shown in FIG. 6, the laser apparatus 1 according to the present embodiment includes a light source unit 410, a condensing optical system 420, and an optical fiber 430. In the laser device 1, after the light emitted from the light source unit 410 is collected by the condensing optical system 420, the light enters the one end of the optical fiber 430 that is a transmission member, and the laser light is emitted from the other end of the optical fiber 430. Is done.

  The light source unit 410 includes a surface emitting laser array element 100A, a heat sink 200, and a microlens array 413. The surface emitting laser array element 100A is an element having an array structure in which a plurality of surface emitting laser elements 100 are arranged one-dimensionally or two-dimensionally. The microlens array 413 is an element having an array structure in which a plurality of microlenses are arranged one-dimensionally or two-dimensionally. Each microlens constituting the microlens array 413 is arranged on the optical path of light emitted from each surface emitting laser element 100 constituting the surface emitting laser array element 100A.

  The light emitted from each surface-emitting laser element 100 constituting the surface-emitting laser array element 100A is a laser beam having an emission angle for each surface-emitting laser element 100, and passes through the microlens array 413 and becomes parallel light. Become. The light that has become parallel light enters the condensing optical system 420.

  The condensing optical system 420 is an optical system that efficiently condenses the light emitted from the light source unit 410 into a small spot and enters the optical fiber 430. The condensing optical system 420 may consist of a single lens or a plurality of lenses.

  The optical fiber 430 transmits the light collected by the condensing optical system 420. The optical fiber 430 has a two-layer structure including a core 431 at the center and a clad 432 covering the periphery thereof. The light condensed by the condensing optical system 420 enters the core 431 of the optical fiber 430.

  In the light source unit 410 according to the second embodiment, the laser light emitted from the surface emitting laser array element 100A is converted into parallel light by the microlens array 413. Thereby, it is possible to output parallel laser light with uniform light output in the plane.

  In FIG. 6, the light source unit 410 having the surface emitting laser array element 100 </ b> A, the heat sink 200, and the microlens array 413 has been described as an example, but a configuration having one light source and one lens may be used. That is, a light source unit having one microlens that converts light emitted from one surface emitting laser element 100 into parallel light may be used.

<Third Embodiment>
In 3rd Embodiment, the example of the laser apparatus and ignition device which have the light source unit which concerns on 2nd Embodiment is shown. Note that in the third embodiment, description of the same components as those of the already described embodiments may be omitted.

  FIG. 7 is a schematic configuration diagram illustrating an ignition device according to the third embodiment. FIG. 8 is a diagram illustrating a laser resonator of the ignition device shown in FIG.

  As shown in FIG. 7 as an example, the ignition device 1301 includes a laser device 1200, an emission optical system 1210, a protection member 1212, and the like.

  The emission optical system 1210 condenses the light emitted from the laser device 1200. Thereby, a high energy density can be obtained at the condensing point.

  The protection member 1212 is a transparent window provided facing the combustion chamber. Here, as an example, sapphire glass is used as the material of the protection member 1212.

  The laser device 1200 includes a light source unit 410 including a surface emitting laser array element 100A, a first condensing optical system 1203, an optical fiber 1204, a second condensing optical system 1205, and a laser resonator 1206. In the present specification, an explanation will be given using the XYZ three-dimensional orthogonal coordinate system and assuming that the light emission direction from the surface emitting laser array element 100A is the + Z direction.

  The surface emitting laser array element 100A is an excitation light source. Here, it is assumed that the wavelength of light emitted from each surface emitting laser element 100 constituting the surface emitting laser array element 100A is 808 nm.

  The surface-emitting laser array element 100A is a light source that is advantageous for exciting a Q-switched laser whose characteristics change greatly due to the deviation of the excitation wavelength because the wavelength deviation due to the temperature of the emitted light is very small. Therefore, when the surface emitting laser array element 100A is used as an excitation light source, there is an advantage that environmental temperature control can be simplified.

  The first condensing optical system 1203 condenses the light emitted from the light source unit 410. The optical fiber 1204 serving as a transmission member is disposed so that the center of the end face on the −Z side of the core is located at a position where the light is collected by the first condensing optical system 1203. Here, an optical fiber having a core diameter of 1.5 mm and an NA of 0.39 (made by Thorlabs, model number: FT1500UMT) is used as the optical fiber 1204.

  By providing the optical fiber 1204, the surface emitting laser array element 100 A can be placed at a position away from the laser resonator 1206. Thereby, the freedom degree of arrangement design can be increased. Further, when the laser device 1200 is used in an ignition device, the surface emitting laser array element 100A can be moved away from the heat source, so that the range of methods for cooling the engine can be increased.

  The light incident on the optical fiber 1204 propagates in the core and is emitted from the end face on the + Z side of the core.

  The second condensing optical system 1205 is disposed on the optical path of the light emitted from the optical fiber 1204 and condenses the light. The light condensed by the second condensing optical system 1205 enters the laser resonator 1206.

  The laser resonator 1206 is a Q-switched laser, and includes a laser medium 1206a and a saturable absorber 1206b as shown in FIG. 8 as an example.

  The laser medium 1206a is a rectangular parallelepiped Nd: YAG crystal of 3 mm × 3 mm × 8 mm, and Nd is doped by 1.1%. The saturable absorber 1206b is a cuboidal Cr: YAG crystal of 3 mm × 3 mm × 2 mm, and has an initial transmittance of 30%.

  Here, the Nd: YAG crystal and the Cr: YAG crystal are joined to form a so-called composite crystal. Both the Nd: YAG crystal and the Cr: YAG crystal are ceramics.

  The light from the second condensing optical system 1205 enters the laser medium 1206a. That is, the laser medium 1206a is excited by the light from the second condensing optical system 1205. The wavelength of light emitted from the surface emitting laser array element 100A is the wavelength with the highest absorption efficiency in the YAG crystal. The saturable absorber 1206b operates as a Q switch.

  The surface on the incident side (−Z side) of the laser medium 1206a and the surface on the exit side (+ Z side) of the saturable absorber 1206b are subjected to an optical polishing process and serve as a mirror. Hereinafter, for convenience, the incident-side surface of the laser medium 1206a is also referred to as a “first surface”, and the exit-side surface of the saturable absorber 1206b is also referred to as a “second surface” (see FIG. 8).

  The first surface and the second surface are coated with a dielectric film corresponding to the wavelength of light emitted from the surface emitting laser array element 100A and the wavelength of light emitted from the laser resonator 1206. Yes.

  Specifically, the first surface has a high transmittance of 99.5% for light with a wavelength of 808 nm and a high reflectance of 99.5% for light with a wavelength of 1064 nm. Has been made. The second surface is coated with a 50% reflectivity for light having a wavelength of 1064 nm.

  Thus, the light resonates and is amplified in the laser resonator 1206, and laser light having a wavelength of 1064 nm is emitted from the second surface. Here, the resonator length of the laser resonator 1206 is 10 (= 8 + 2) mm.

  Returning to FIG. 7, the drive device 1220 drives the surface emitting laser array element 100 </ b> A based on an instruction from the engine control device 1222. That is, drive device 1220 drives surface-emitting laser array element 100A so that light is emitted from the ignition device at the timing of ignition in engine operation. A plurality of light emitting sections (surface emitting laser element 100) in surface emitting laser array element 100A are turned on and off simultaneously.

  In the above embodiment, when it is not necessary to place the surface emitting laser array element 100A at a position away from the laser resonator 1206, the optical fiber 1204 may not be provided.

  Further, each of the first condensing optical system 1203, the second condensing optical system 1205, and the emission optical system 1210 may be composed of a single lens or a plurality of lenses.

  Further, instead of the light source unit 410, a light source unit having one microlens that makes light emitted from one surface emitting laser element 100 parallel light may be used.

  Further, the engine may be an engine (piston engine) that moves a piston by combustion gas, or may be a rotary engine, a gas turbine engine, or a jet engine. In short, any internal combustion engine that burns fuel and generates combustion gas may be used.

  In addition, an ignition device may be used for cogeneration, which is a system that uses exhaust heat to extract power, heat, and cold to improve energy efficiency comprehensively.

  Although the case where the ignition device is used in an internal combustion engine has been described here, the present invention is not limited to this.

  Although the case where the laser device 1200 is used in an ignition device has been described here, the present invention is not limited to this. For example, the laser device 1200 can be used for a laser processing machine, a laser peening device, a terahertz generator, and the like.

  The preferred embodiment has been described in detail above. However, the present invention is not limited to the above-described embodiment, and various modifications and replacements are made to the above-described embodiment without departing from the scope described in the claims. Can be added.

DESCRIPTION OF SYMBOLS 1 Laser apparatus 100 Surface emitting laser element 100A Surface emitting laser array element 110 1st reflective mirror 120 Cavity structure 121 Lower spacer layer 122 Active layer 122a GaInAs layer 122b GaAs layer 123 Upper spacer layer 130 2nd reflecting mirror 140 2nd reflector 140 One electrode 141 First region 141x Through hole 142 Second region 150 Insulating film 160 Second electrode 200 Heat sink 410 Light source unit 413 Microlens array 420 Condensing optical system 430 Optical fiber 431 Core 432 Clad 1200 Laser device 1203 First DESCRIPTION OF SYMBOLS 1 Condensing optical system 1204 Optical fiber 1205 2nd condensing optical system 1206 Laser resonator 1206a Laser medium 1206b Saturable absorber 1210 Emission optical system 1212 Protection member 1220 Driving device 1222 d Jin controller 1301 ignition device

PHOTONICS TECHNLOGY LETTERS, VOL.10, NO.8, (1998) 1061 Applied Physics Express, 4, (2011) 052102

Claims (12)

A first reflecting mirror and a second reflecting mirror formed so as to sandwich the active layer;
A first electrode connected to the first reflecting mirror;
A second electrode connected to the second reflecting mirror,
A surface-emitting laser element that emits laser light from the second reflecting mirror side,
The first electrode has a first region formed of a first material that forms an ohmic contact with a semiconductor material constituting the first reflecting mirror, and has a higher thermal conductivity than the first material. A second region formed of a second material,
The surface emitting laser element, wherein the first region and the second region are in contact with the first reflecting mirror.   2. The surface emitting laser element according to claim 1, wherein the first reflecting mirror is a p-type semiconductor.   3. At least one of the first region and the second region is formed by a single metal material or a structure in which a single metal material is laminated. The surface emitting laser element according to 1. A plurality of through holes are formed in the first region,
4. The surface-emitting laser element according to claim 1, wherein the second region is formed of the second material filling each through-hole. 5. The first electrode is formed on a surface of the first reflecting mirror opposite to the laser light emission side,
The second electrode is formed in an annular shape on a surface on the laser light emission side of the second reflecting mirror,
5. The surface light emission according to claim 1, wherein the first electrode is formed inside an opening of the second electrode when viewed from a normal direction of a surface on the laser light emission side. 6. Laser element.   6. A surface-emitting laser array element in which a plurality of surface-emitting laser elements according to claim 1 are arranged. A surface emitting laser element according to any one of claims 1 to 5,
A light source unit comprising: a microlens that collimates light emitted from the surface-emitting laser element. A surface emitting laser array element according to claim 6,
A light source unit comprising: a microlens array that collimates light emitted from the surface emitting laser array element. The light source unit according to claim 7 or 8,
And a condensing optical system for condensing light emitted from the light source unit.   The laser apparatus according to claim 9, further comprising a laser resonator on which light through the condensing optical system is incident.   The laser device according to claim 10, further comprising a transmission member that transmits light through the condensing optical system to the laser resonator.   An ignition device comprising: the laser device according to claim 9; and an optical system that collects light emitted from the laser device.

Images