JP6938977B2 - Surface emitting laser element, surface emitting laser array element, light source unit, laser device, ignition device - Google Patents

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

The surface emitting laser element has a feature that mode hop does not occur in principle and the wavelength stability is excellent. On the other hand, the surface emitting laser element has a structure in which the active layer is sandwiched between the reflecting mirrors, so that it is difficult to dissipate heat, and it is not suitable for increasing the output. Therefore, 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.

As a method for expanding the surface emitting laser element while controlling the injection area, for example, a technique has been proposed in which the laser beam is emitted on the n-side and the injection region is controlled by the shape of the p-side electrode (for example, non-patent documents). See 1 and 2).

However, with the above technique, the heat dissipation characteristics are not sufficiently improved, 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 surface emitting laser element having high output.

The surface emitting laser element includes 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, and the second reflection. A surface emitting laser element having a second electrode connected to a mirror and emitting laser light from the second reflecting mirror side, wherein the first electrode is a surface emitting laser element that emits the first reflecting mirror. A first region formed of a first material forming an ohmic contact with the constituent semiconductor material, a second region formed of a second material having a higher thermal conductivity than the first material, and a second region. The first region and the second region come into contact with the first reflecting mirror, and a plurality of through holes are formed in the first region, and the first through holes are filled. It is a requirement that the second region is formed by the material of 2.

According to the disclosed technique, 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 which illustrates the surface emitting laser element which concerns on 1st Embodiment. It is a top view which illustrates the surface emitting laser element which concerns on 1st Embodiment. It is sectional drawing which illustrates the surface emitting laser element which concerns on Comparative Example 1. FIG. It is sectional drawing which illustrates the surface emitting laser element which concerns on 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. 7.

Hereinafter, modes for carrying out the invention will be described with reference to the drawings. In each drawing, the same components may be designated by the same reference numerals and duplicate description may be omitted.

<First Embodiment>
FIG. 1 is a diagram illustrating a surface emitting laser element according to the first embodiment, FIG. 1 (a) is a cross-sectional view, and FIG. 1 (b) is a partially enlarged cross-sectional view of part A of FIG. 1 (a). It is a figure. 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, the surface emitting laser element 100 is, for example, a vertical resonator type laser element having an oscillation wavelength in the 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 any other wavelength.

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

In the surface emitting laser element 100, the layer made of a semiconductor 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 or the like. 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 to the outside from the heat sink 200 via 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 the front surface side or the upper side, and the first electrode 140 side is the back surface side or the lower side. Further, the surface of each part on the second electrode 160 side is the front surface or the upper surface, and the surface on the first electrode 140 side is the back surface or the lower surface. However, the surface emitting laser element 100 can be used in an upside-down state, or can be arranged at an arbitrary angle. Further, the shape of each component of the surface emitting laser element 100 as viewed from the light emitting direction may be referred to as a planar shape. Further, a direction orthogonal 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 reflector 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. Has 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 inclined layer, the electric resistance can be reduced. The low refractive index layer and the high refractive index layer can be designed so that the optical thickness is λ / 4 with respect to the oscillation wavelength λ, including 1/2 the thickness of the adjacent composition gradient layer. 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 laminated 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 laminated from the first reflector 110 side. The lower spacer layer 121 and the upper spacer layer 123 can be formed of, for example, GaAs or the like.

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

When the oscillation wavelength of the surface emitting laser element 100 is 1064 nm, the oscillation wavelength of the GaInAs layer 122a is adjusted to be, 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 laminated on the upper spacer layer 123. The second reflecting mirror 130 is also referred to as 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 inclined layer, the electric resistance can be reduced. The low refractive index layer and the high refractive index layer can be designed so that the optical thickness is λ / 4 with respect to the oscillation wavelength λ, including 1/2 the thickness of the adjacent composition gradient layer.

A current constriction layer may be provided as one of the low refractive index layers in the second reflector 130. The current constriction layer can be configured to include, for example, an oxidized selective oxidation region and an unoxidized current passage region. The selective oxidation region can be formed by oxidizing the current constriction 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 beam emitting side), and is electrically connected to the first reflecting mirror 110. As shown in FIG. 2A, the planar shape of the first electrode 140 can be, for example, a circle, but is not limited to this, and may be an ellipse, a rectangle, a polygon, or any other shape. Can be done.

An insulating film 150 in contact with the lower surface of the first reflecting mirror 110 is provided around the first electrode 140. As the 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. The lower surface of the first electrode 140 and the lower surface of the insulating film 150 can be flush with each other, for example.

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

As the first material forming the first region 141, a material forming ohmic contact with the semiconductor material constituting the first reflector 110 can be selected. The first region 141 can be, for example, a monolayer film. In this case, the monolayer film may be formed of a single material or may be formed of an alloy of two or more kinds of materials. Further, the first region 141 may be a laminated film in which different materials are laminated.

Generally, it is said that the smaller the number of constituent elements, the higher the thermal resistance of the material, and by selecting such a material, the heat dissipation 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, which is a binary alloy, can be used as the first material. Alternatively, as the first material, an AuZn / Au laminated film in which an AuZn film and an Au film are sequentially laminated from the side of the first reflecting mirror 110 may be used.

As the second material, a material having a higher thermal conductivity than the first material can be selected. When 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, a first region 141 is formed on the lower surface of the first reflecting mirror 110 by vapor deposition, sputtering, plating, or the like to be larger than the final shape. After that, the first region 141 is patterned by lift-off, etching, or the like. By patterning, for example, a first region 141 that is entirely circular and has 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 reflector 110.

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

The second electrode 160 is formed in contact with the upper surface (the surface on the emission side of the laser beam) of the second reflecting mirror 130, and is electrically connected to the second reflecting mirror 130. The second electrode 160 forms ohmic contact with the second reflector 130. As shown in FIG. 3, the planar shape of the second electrode 160 can 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. It may be an annular shape in which a part of a polygon is opened, or an annular shape in which a part of any other shape is opened.

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

For example, when the material of the layer in contact with the second electrode 160 in the second reflecting mirror 130 is GaAs, for example, AuGe, which is a binary alloy, can be used as the material of the second electrode 160. .. 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 side of the second reflecting mirror 130 may be used. The second electrode 160 can be formed by, for example, vapor deposition, sputtering, plating, or the like.

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

When the first electrode 140 and the second electrode 160 of the surface emitting laser element 100 are connected to the voltage applying means, the p-type carriers (holes) injected from the first electrode 140 and the second electrode 160 are injected. The n-type carriers (electrons) are each diffused and uniformly injected into the active layer 122. As a result, the carriers reach the population inversion inside the active layer 122, and the laser beam 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 injecting carriers into the active layer 122. The carriers to be injected are holes and electrons, and these carriers have a constant mobility depending on the temperature and the conductive material. However, there is a difference of about 1000 times in the mobility of both, and holes have 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 recombination is realized in the active layer 122 to realize laser oscillation.

At this time, the holes, which are p-type carriers injected from the first electrode 140, have a low mobility, so that the holes are directed in a direction parallel to the first reflecting mirror 110 and the second reflecting mirror 130. Reach the active layer 122 without much diffusion.

The diffusion of holes, which 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. When the thickness of the reflector 110 is about 4 μm, it diffuses about 5 μm while conducting about 4 μm.

On the other hand, since the electrons injected from the second electrode 160 have high mobility, they diffuse to reach the active layer 122 even in the direction parallel to the first reflecting mirror 110 and the second reflecting mirror 130. 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.

In the first electrode 140, the second material gives priority to heat dissipation characteristics, and ohmic contact with the semiconductor material of the first reflector 110 is not secured. Therefore, carriers are used at a voltage below the Schottky barrier. Not injected. Therefore, in order to uniformly inject the 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 a current into the active layer 122, it is possible to realize a surface emitting laser element 100 having a uniform beam intensity and a controlled beam shape.

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 to realize uniform carrier injection over a large area and increase the output. Is possible.

Further, the surface emitting laser element 100 has improved heat dissipation characteristics as compared with the conventional surface emitting laser element, and can further increase the output. This will be described with reference to FIGS. 4 and 5.

FIG. 4 is a cross-sectional view illustrating the 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 expanded. In the surface emitting laser element 100x, the first electrode 140x is formed only of the first material that forms ohmic contact with the semiconductor material that constitutes the first reflecting mirror 110.

In the surface emitting laser element 100x, the heat generated by carrier injection into the active layer 122 is released to the outside from the heat sink 200. In the case of the surface emitting laser element 100x, since the opposite side of the heat sink 200 is the injection 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) bypassing the active layer 122, which is a heat generation source.

FIG. 5 is a cross-sectional view illustrating the 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 the current injection region is expanded. In the surface emitting laser element 100y, the first electrode 140y is formed of only the first material that forms ohmic contact with the semiconductor material that constitutes 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 has been clarified by thermal simulation that the heat (part B) generated near the center of the active layer 122 becomes difficult to be released to the outside due to the heat generated in the peripheral portion as a barrier.

That is, when considering increasing the output of the surface emitting laser element, it is not enough to simply increase the current injection area, and it is necessary to improve the heat dissipation characteristics. Specifically, since the heat dissipation path is only the lower part of the active layer 122, the thermal resistance of the lower part of 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 forming ohmic contact with the semiconductor material constituting the first reflecting mirror 110 and the first material. It is made of a second material.

As a result, it is possible to connect to the semiconductor material constituting the first reflecting mirror 110 with low resistance, and the heat of the lower part of the active layer 122 is higher than that in the case where the first electrode 140 is formed only by the first material. The resistance can be reduced and the heat dissipation characteristics can be improved. As a result of improving the heat dissipation characteristics, in the surface emitting laser element 100, it is possible to further increase the output as compared with the case where the first electrode 140 is formed only by the first material.

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

Therefore, in the present embodiment, the first electrode 140 has a first material that forms an ohmic contact with the semiconductor material constituting the first reflector 110, and the first material has a higher thermal conductivity than the first material. By forming the first electrode 140 in combination with the second material, it can be connected to the semiconductor material constituting the first reflecting mirror 110 with low resistance, and compared with the case where the first electrode 140 is formed only with the first material. The surface emitting laser element 100 having improved heat dissipation characteristics has been realized. As a result of improving the heat dissipation characteristics, in the surface emitting laser element 100, it is possible to further increase the output as compared with the case where the first electrode 140 is formed only of the first material (in the case of FIG. 5 and the like). ..

In the above description, the first electrode 140 has a first material that forms ohmic contact with the semiconductor material constituting the first reflector 110, and a second material having a higher thermal conductivity than the first material. As an example of forming in combination with the above materials, an example is shown in which a plurality of substantially circular through holes 141x formed in the first region 141 are filled with the second material to form the second region 142 (. See FIG. 2 (b)).

However, the shapes and arrangements of the first region 141 and the second region 142 constituting the first electrode 140 are not limited to the example of FIG. 2B. For example, the through holes 141x of the first region 141 may be formed in a striped shape or a slit shape, and each through hole 141x may be filled with a second material to form the second region 142. Alternatively, the shape of the through hole 141x may be other than these. 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 the current into the active layer 122 as described above.

<Second Embodiment>
The second embodiment shows an example of a light source unit and a laser device having a surface emitting laser element according to the first embodiment. In the second embodiment, the description of the same components as those in the above-described embodiment may be omitted.

FIG. 6 is a schematic configuration diagram illustrating the laser apparatus according to the second embodiment. As shown in FIG. 6, the laser device 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 condensed by the condensing optical system 420, it is incident on one end of the optical fiber 430 which is a transmission member, and the laser light is emitted from the other end of the optical fiber 430. Will be 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 an 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 a radiation angle for each surface emitting laser element 100, and becomes parallel light by passing through the microlens array 413. Become. The light that has become parallel light is incident on 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 onto a small spot and causes it to enter the optical fiber 430. The condensing optical system 420 may be composed of a single lens or may be composed of 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 collected by the focusing optical system 420 is incident on 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 made into parallel light by the microlens array 413. As a result, it is possible to output a parallel light laser beam having a uniform light output in the plane.

Although the light source unit 410 having the surface emitting laser array element 100A, the heat sink 200, and the microlens array 413 has been described as an example in FIG. 6, the configuration may include one light source and one lens. That is, it may be a light source unit having one microlens in which the light emitted from one surface emitting laser element 100 is parallel light.

<Third embodiment>
The third embodiment shows an example of a laser device and an ignition device having a light source unit according to the second embodiment. In the third embodiment, the description of the same components as those in the above-described embodiment may be omitted.

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

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

The emission optical system 1210 collects the light emitted from the laser apparatus 1200. This makes it possible to obtain a high energy density at the condensing point.

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

The laser apparatus 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 this specification, the XYZ three-dimensional Cartesian coordinate system is used, and the emission direction of light from the surface emitting laser array element 100A is described as the + Z direction.

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

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

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

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

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

The second condensing optical system 1205 is arranged on the optical path of the light emitted from the optical fiber 1204, and condenses the light. The light focused by the second focusing optical system 1205 is incident on the laser resonator 1206.

The laser cavity 1206 is a Q-switched laser and has 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 with 1.1%. The saturable absorber 1206b is a 3 mm × 3 mm × 2 mm rectangular parallelepiped Cr: YAG crystal having an initial transmittance of 30%.

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

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

The surface of the laser medium 1206a on the incident side (−Z side) and the surface of the saturable absorber 1206b on the injection side (+ Z side) are subjected to optical polishing treatment and serve as a mirror. In the following, for convenience, the surface on the incident side of the laser medium 1206a is also referred to as a "first surface", and the surface on the injection side of the saturable absorber 1206b is also referred to as a "second surface" (see FIG. 8).

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

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

As a result, the light resonates and is amplified in the laser resonator 1206, and the laser beam 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 100A based on the instruction of the engine control device 1222. That is, the drive device 1220 drives the surface emitting laser array element 100A so that light is emitted from the ignition device at the ignition timing in the operation of the engine. The plurality of light emitting units (surface emitting laser element 100) in the surface emitting laser array element 100A are turned on and off at the same time.

In the above embodiment, if 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, the first condensing optical system 1203, the second condensing optical system 1205, and the emission optical system 1210 may all be composed of a single lens or may be composed of a plurality of lenses.

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

Further, the engine may be an engine (piston engine) in which a piston is moved by combustion gas, a rotary engine, a gas turbine engine, or a jet engine. In short, it may be an internal combustion engine that burns fuel to generate combustion gas.

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

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

Further, although the case where the laser device 1200 is used for the 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.

Although the preferred embodiment has been described in detail above, it is not limited to the above-described embodiment, and various modifications and substitutions are made to the above-described embodiment without departing from the scope of the claims. Can be added.

1 Laser device 100 Surface emitting laser element 100A Surface emitting laser array element 110 First reflecting mirror 120 Resonator structure 121 Lower spacer layer 122 Active layer 122a GaInAs layer 122b GaAs layer 123 Upper spacer layer 130 Second reflecting mirror 140th 1 electrode 141 1st region 141 x through hole 142 2nd region 150 Insulation film 160 2nd 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 1 Condensing optics 1204 Optical fiber 1205 Second condensing optics 1206 Laser resonator 1206a Laser medium 1206b Saturable absorber 1210 Ejection optics 1212 Protective member 1220 Drive device 1222 Engine control device 1301 Ignition device

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

Claims (11)

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

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