JP2017098532A - Face light emission laser array and laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of light intensity in a light emission area.SOLUTION: A face light emission laser array comprises: a light emission area 14 in which a plurality of face light emission laser elements 21 are arranged; and a current path along which current is supplied to the face light emission laser elements 21 from an outer peripheral part 26 of the light emission area 14. The interval between the face light emission laser elements 21 in the outer peripheral part 26 of the light emission area 14 is larger than that in a central part 25 thereof. The light emission area 14 has a shape that is point-symmetrical around the center part 25. The light emission area 14 includes three or more areas 41, 42, 43 of different intervals D1, D2, D3.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a surface emitting laser array and a laser apparatus.

  As a laser light source, a surface emitting laser array in which a plurality of surface emitting laser elements (VCSEL: Vertical Cavity Surface Emitting Laser) are arranged in a plane is used.

  For example, in order to reduce the adverse effect of heat generated by light emitting elements (surface emitting laser elements) arranged at high density, the distance between the plurality of light emitting elements is larger in the central portion than in the outer peripheral portion of the light emitting region. A surface emitting laser array is disclosed (Patent Document 1).

  As a current path of the surface emitting laser array, a path for supplying current from the outer peripheral portion of the light emitting region to each light emitting element can be considered. In a surface emitting laser array employing such a current path, when a plurality of light emitting elements are uniformly arranged over the entire light emitting region, the current density at the outer peripheral portion of the light emitting region is larger than the current density at the central portion. When such a current density deviation occurs, the light intensity of the light emitting element arranged near the outer peripheral portion becomes larger than the light intensity of the light emitting element arranged near the central portion. Is damaged.

  The present invention has been made in view of the above, and an object thereof is to improve the uniformity of light intensity in a light emitting region.

  In order to solve the above-described problems and achieve the object, the present invention includes a light emitting region in which a plurality of surface emitting laser elements are arranged, and a current that supplies current from the outer periphery of the light emitting region to the surface emitting laser element. A surface-emitting laser array in which the distance between the plurality of surface-emitting laser elements is larger on the outer peripheral side than on the center side of the light-emitting region.

  According to the present invention, it is possible to improve the uniformity of the light intensity in the light emitting region.

FIG. 1 is a side sectional view showing a configuration of a surface emitting laser array according to an embodiment. FIG. 2 is a side cross-sectional view showing the configuration of the light emitting device according to the embodiment. FIG. 3 is a diagram illustrating a state in which the surface emitting laser array according to the embodiment is bonded onto the submount. FIG. 4 is a top view showing the configuration of the surface emitting laser array according to the embodiment. FIG. 5 is a diagram illustrating a first example of the arrangement and interval of the light emitting elements according to the embodiment. FIG. 6 is a diagram illustrating a second example of the arrangement and interval of the light emitting elements according to the embodiment. FIG. 7 is a diagram illustrating a light emitting region according to the first example of the embodiment. FIG. 8 is a diagram showing the interval between the light emitting elements in the light emitting region shown in FIG. FIG. 9 is a diagram illustrating a relationship between the amount of current and the light intensity of the surface emitting laser array according to the embodiment. FIG. 10 is a diagram illustrating a correspondence relationship between the light emitting region and the light intensity according to the embodiment. FIG. 11 is a diagram illustrating a light emitting region according to a second example of the embodiment. FIG. 12 is a diagram illustrating a light emitting region according to a third example of the embodiment. FIG. 13 is a diagram illustrating a light emitting region according to a fourth example of the embodiment. FIG. 14 is a diagram illustrating a light emitting region according to a fifth example of the embodiment. FIG. 15 is a diagram illustrating a light emitting region according to a sixth example of the embodiment. FIG. 16 is a diagram illustrating a light emitting region according to a seventh example of the embodiment. FIG. 17 is a diagram illustrating a light emitting region according to an eighth example of the embodiment. FIG. 18 is a diagram illustrating the spacing of the light emitting elements in each region within the light emitting region according to the eighth example of the embodiment. FIG. 19 is a diagram schematically illustrating a configuration of a main part of the engine according to the embodiment. FIG. 20 is a diagram illustrating a configuration of the ignition device according to the embodiment. FIG. 21 is a diagram illustrating a configuration of a laser resonator according to the embodiment.

  FIG. 1 is a side sectional view showing a configuration of a surface emitting laser array 1 according to an embodiment. The surface emitting laser array 1 includes a semiconductor substrate 11, an upper electrode 12 (positive electrode), a lower electrode 13 (negative electrode), and a light emitting region 14.

  In the light emitting region 14, a plurality of surface emitting laser elements (hereinafter abbreviated as light emitting elements) 21 are arranged in a plane. Each light emitting element 21 emits laser light 22 in a direction (Z direction) perpendicular to the surface of the light emitting region 14. The number of light emitting elements 21 shown in FIG. 1 is merely an example, and does not suggest the number of light emitting elements 21 in the actual surface emitting laser array 1.

  The surface emitting laser array 1 includes a current path for supplying a current to each light emitting element 21. The current path includes the upper electrode 12 and the lower electrode 13.

  The upper electrode 12 is disposed on the upper surface (surface on the Z direction side) of the semiconductor substrate 11. The lower electrode 13 is disposed on the lower surface (surface opposite to the Z direction) of the semiconductor substrate 11. The main constituent material of the upper electrode 12 and the lower electrode 13 is preferably Au, but may be Cu or the like. The upper electrode 12 functions as an anode, and the lower electrode 13 functions as a cathode. Both or one of the upper electrode 12 and the lower electrode 13 may be a common electrode connected to all the light emitting elements 21. When the upper electrode 12 and the lower electrode 13 are common electrodes, a plurality of light emitting elements 21 can be driven simultaneously without constructing a complicated current path.

  FIG. 2 is a side sectional view showing a configuration of the light emitting element 21 according to the embodiment. The light emitting element 21 includes a semiconductor substrate 11, an upper electrode 12, a lower electrode 13, reflection layers 31 and 32, an active layer 33, a selective oxidation layer 34, a contact layer 35, and an emission port 37. When the current flows from the upper electrode 12 to the lower electrode 13, the laser beam 22 resonated in the direction parallel to the Z direction is emitted from the emission port 37 in the Z direction. The configuration illustrated in FIG. 2 is merely an example, and as the configuration of the light-emitting element 21, a known or novel configuration related to the VCSEL can be appropriately employed.

  FIG. 3 is a diagram illustrating a state in which the surface emitting laser array 1 according to the embodiment is bonded onto the submount 51. The submount 51 includes a substrate 61, an anode film 62, a cathode film 63, an anode rod 64, and a cathode rod 65. The anode film 62 and the cathode film 63 are members made of a conductive material such as Au or Cu, and are fixed on the substrate 61 made of ceramics or the like by vapor deposition or the like. The anode film 62 has a concave shape when viewed from above. The cathode film 63 has a convex shape when viewed from above. The anode film 62 and the cathode film 63 are formed so that the concave portion of the anode film 62 and the convex portion of the cathode film 63 are fitted, and a predetermined gap is formed between the anode film 62 and the cathode film 63. Have been placed. The anode rod 64 and the cathode rod 65 are members made of a conductive material such as Au or Cu. One end of the anode rod 64 is connected to the positive electrode of the power source, and the other end is connected to the anode film 62. One end side of the cathode rod 65 is connected to the negative electrode of the power source, and the other end side is connected to the cathode film 63.

  The surface emitting laser array 1 according to the present embodiment is die-bonded on the cathode film 63, and the lower electrode 13 of the surface emitting laser array 1 is connected to the cathode film 63. The upper electrode 12 of the surface emitting laser array 1 is connected to the anode film 62 via a plurality of bonding wires 71. The bonding wires 71 are installed along three sides facing the anode film 62 among the four sides of the surface emitting laser array 1.

  By connecting the surface emitting laser array 1 and the submount 51 as described above, current is supplied to each light emitting element 21 from the outer periphery of the light emitting region 14 via the upper electrode 12. Note that the current path (path for supplying current from the outer peripheral portion of the light emitting region 14 to each light emitting element 21) is not limited to the above, and can be constructed by appropriately using a known or novel configuration.

  FIG. 4 is a top view showing the configuration of the surface emitting laser array 1 according to the embodiment. In this example, a circular light emitting region 14 is formed in the center of the square upper electrode 12 (semiconductor substrate 11). The light emitting region 14 preferably has a point-symmetric shape with the central portion 25 as a symmetry point.

  The light emitting region 14 according to this example includes a first region 41, a second region 42, and a third region 43. The first region 41, the second region 42, and the third region 43 have different intervals between the plurality of light emitting elements 21 disposed inside. The interval between the light emitting elements 21 in the first region 41 is smaller than the interval between the light emitting elements 21 in the second region 42 and the third region 43. The interval between the light emitting elements 21 in the second region 42 is larger than the interval between the light emitting elements 21 in the first region 41 and smaller than the interval between the light emitting elements 21 in the third region 43. The interval between the light emitting elements 21 in the third region 43 is larger than the interval between the light emitting elements 21 in the first region 41 and the second region 42. The number of regions with different intervals between the light emitting elements 21 is preferably as large as possible, and is preferably 3 levels or more. Moreover, the change of the space | interval of the light emitting element 21 may be seamless.

  FIG. 5 is a diagram illustrating a first example of the arrangement and interval of the light emitting elements 21 according to the embodiment. The plurality of light emitting elements 21 according to this example are arranged so that the intervals in the X direction are uniform and the positions of the two light emitting elements 21 adjacent in the Y direction are shifted from each other. In the figure, Dx is an interval between two light emitting elements 21 adjacent in the X direction. In the figure, Dy is an interval between two element rows adjacent to the Y direction (an element row made up of a plurality of light emitting elements 21 equally arranged in the X direction).

  FIG. 6 is a diagram illustrating a second example of the arrangement and interval of the light emitting elements 21 according to the embodiment. The plurality of light emitting elements 21 according to this example are arranged so that the intervals in the X direction and the intervals in the Y direction are equal. In the figure, Dx is an interval between two light emitting elements 21 adjacent in the X direction. In the figure, Dy is an interval between two light emitting elements 21 adjacent in the Y direction.

  The first region 41, the second region 42, and the third region 43 can be formed by changing the distance between the light emitting elements 21 as exemplified by the above Dx and Dy. For example, Dx and Dy in the first region 41 are made smaller than Dx and Dy in the second region 42 and the third region 43, and Dx and Dy in the second region 42 are Dx, Dy in the first region 41. It may be made larger and smaller than Dx and Dy in the third region 43, and Dx and Dy in the third region 43 may be made larger than Dx and Dy in the first region 41 and the second region 42. In addition, the arrangement | sequence, space | interval, shape, etc. of the light emitting element 21 are not restricted above, A well-known or novel structure can be applied suitably.

  FIG. 7 is a diagram illustrating the light emitting region 14 according to the first example of the embodiment. FIG. 8 is a diagram showing intervals D1, D2, D3 (corresponding to Dx) of the light emitting elements 21 in the light emitting region 14 shown in FIG. The distance D1 between the light emitting elements 21 in the first region 41, the distance D2 between the light emitting elements 21 in the second region 42, and the distance D3 between the light emitting elements 21 in the third region 43 have a relationship of D1 <D2 <D3. .

  Note that the relationship regarding the interval between the light emitting elements 21 such as D1 <D2 <D3 does not necessarily have to hold for all the light emitting elements 21. For example, when the density of the light emitting element 21 in the first region 41 is De1, the density of the light emitting element 21 in the second region 42 is De2, and the density of the light emitting element 21 in the third region 43 is De3> De1> When the relationship of De2> De3 is established, the same effect as that obtained by the relationship of D1 <D2 <D3 can be obtained. In the example shown in FIG. 8, the number of light emitting elements 21 per unit area S1 in the first region 41 is 14, and the number of light emitting elements 21 per unit area S1 in the second region 42 is four. The number of the light emitting elements 21 per unit area S1 in the third region 43 is three. If such a magnitude relationship is maintained for the regions 41, 42, and 43 as a whole, the relationship of D1 <D2 <D3 may not be partially maintained.

  The shape shown in FIGS. 7 and 8, the number of light emitting elements 21, and the like are merely illustrative examples, and do not suggest the actual shape of the surface emitting laser array 1, the number of light emitting elements 21, or the like. . For example, the number of light emitting elements 21 in the actual surface emitting laser array 1 may be tens of thousands or more. For example, the light emitting region 14 has a diameter of 9 mm, the upper electrode 12 (semiconductor substrate 11) has a size / shape of 12 mm × 12 mm square, the light emitting elements 21 have a size / shape of 30 μm × 30 μm square, the first region The radius of 41 is 2.2 mm, the radius of the second region 42 is 3.4 mm, the radius of the third region 43 is 4.5 mm, D1 is 10 μm, D2 is 15 μm, D3 is 20 μm, and the number of light emitting elements 21 is 3604 surface emitting laser arrays 1 can be manufactured.

  FIG. 9 is a diagram illustrating the relationship between the amount of current and the light intensity of the surface emitting laser array 1 according to the embodiment. A line 45 indicated by a solid line indicates the relationship between the amount of current and the light intensity in the surface emitting laser array 1 according to the present embodiment. A line 46 indicated by a broken line indicates the relationship between the amount of current and the light intensity in the conventional surface emitting laser array.

  The surface emitting laser array 1 according to the present embodiment corresponding to the line 45 and the conventional surface emitting laser array corresponding to the line 46 are different in arrangement and number of light emitting elements 21. As described above, the light emitting elements 21 of the surface emitting laser array 1 according to the present embodiment are arranged so that the distance between them is larger on the outer peripheral portion 26 side than on the central portion 25 side of the light emitting region 14. On the other hand, the light emitting elements of the conventional surface emitting laser array are arranged so that the intervals are uniform over the entire light emitting region. As a result, the number of light emitting elements 21 in the present embodiment is smaller than the number of light emitting elements in the conventional surface emitting laser array. For example, FIG. 9 shows the results when the number of light emitting elements 21 in the present embodiment is 36054 and the number of conventional light emitting elements is 45911.

  As shown in FIG. 9, the relationship between the amount of current and the light intensity in the surface emitting laser array 1 according to the present embodiment is substantially the same as the relationship between the amount of current and the light intensity in the conventional surface emitting laser array. That is, according to the present embodiment, it is possible to obtain light intensity equivalent to that of the prior art by using fewer light emitting elements 21 than in the past and without increasing the amount of current.

  FIG. 10 is a diagram illustrating a correspondence relationship between the light emitting region 14 and the light intensity according to the embodiment. A line 47 indicated by a solid line indicates the light intensity corresponding to the light emitting region 14 according to the present embodiment. A line 48 indicated by a broken line indicates the light intensity corresponding to the conventional light emitting region.

  As indicated by the lines 47 and 48, the light intensity at the central portion 25 of the light emitting region 14 is lower than the light intensity at the outer peripheral portion 26 in both the present embodiment and the conventional structure. This is because the current density at the central portion 25 is smaller than the current density at the outer peripheral portion 26 by supplying the current for driving each light emitting element 21 from the outer peripheral portion 26.

  The difference Δ1 between the light intensity of the outer peripheral portion 26 and the light intensity of the central portion 25 in the present embodiment indicated by the line 47 is the difference between the light intensity of the outer peripheral portion 26 and the light intensity of the central portion 25 in the conventional structure indicated by the line 48. It is smaller than the difference Δ2. In the present embodiment, as described above, since the distance between the light emitting elements 21 is larger in the region closer to the outer peripheral portion 26 as described above, current consumption in the region closer to the outer peripheral portion 26 is suppressed, and the central portion 25 is reduced. This is because a sufficient amount of current is supplied. Thereby, the fall of the light intensity in the center part 25 is suppressed, and the uniformity of the light intensity in the whole light emission area | region 14 is improved.

  In the above embodiment, the circular light emitting region 14 shown in FIG. 7 has been described as an example, but the light emitting region is not limited to this. Below, the variation of the light emission area | region is shown.

  FIG. 11 is a diagram illustrating the light emitting region 50 according to the second example of the embodiment. The light emitting region 50 of this example is a square with the central portion 25 as a point symmetry point. Even if it is such a shape, the effect similar to the light emission area | region 14 concerning the said 1st example can be acquired.

  FIG. 12 is a diagram illustrating a light emitting region 60 according to a third example of the embodiment. The light emitting region 60 in this example is a rectangle having the central portion 25 as a point symmetry point. Even if it is such a shape, the effect similar to the light emission area | region 14 concerning the said 1st example can be acquired.

  FIG. 13 is a diagram illustrating a light emitting region 70 according to a fourth example of the embodiment. The light emitting region 70 of this example is a regular hexagon with the central portion 25 as a point symmetry point. Even if it is such a shape, the effect similar to the light emission area | region 14 concerning the said 1st example can be acquired.

  FIG. 14 is a diagram illustrating a light emitting region 80 according to a fifth example of the embodiment. The light emitting region 80 in this example is a regular octagon with the central portion 25 as a point symmetry point. Even if it is such a shape, the effect similar to the light emission area | region 14 concerning the said 1st example can be acquired.

  As described above, the light emitting regions 50, 60, 70, and 80 may be polygonal, and generally have a shape close to a circle, that is, a polygon having a relatively large number of vertices.

  FIG. 15 is a diagram illustrating a light emitting region 90 according to a sixth example of the embodiment. The light emitting area 90 of this example is circular like the light emitting area 14 according to the first example shown in FIG. 7, but a plurality of light emitting elements 21 arranged inside thereof are arranged radially from the central portion 25. Yes. Even if it is such a shape, the effect similar to the light emission area | region 14 concerning the said 1st example can be acquired.

  FIG. 16 is a diagram illustrating a light emitting region 93 according to a seventh example of the embodiment. The light emitting region 93 of this example includes a first region 41, a second region 42, a third region 43, and a fourth region 44. The distance between the light emitting elements 21 in the first area 41 is D1 (see FIG. 8), the distance between the light emitting elements 21 in the second area 42 is D2 (see FIG. 8), and the distance between the light emitting elements 21 in the third area is the distance. When the distance between the light emitting elements 21 in the fourth region 44 is D4 (see FIG. 16), the relationship of D1 <D2 <D3 <D4 is established. Thus, by setting the number of regions having different intervals of the light emitting elements 21 to four, the number of regions in the light emitting region 93 is larger than that in the case of three regions as in the first example shown in FIG. The effect of improving the uniformity of light intensity can be further increased. Note that the number of regions may be five or more.

  FIG. 17 is a diagram illustrating a light emitting region 95 according to an eighth example of the embodiment. The light emitting region 95 of this example includes a first region 41, a second region 42, and a third region 43. Unlike the light emitting elements 21 arranged in an orderly manner as in the first example shown in FIG. 7, the plurality of light emitting elements 21 arranged in the light emitting region 95 of this example are arranged at random to some extent.

  FIG. 18 is a diagram illustrating the intervals D1, D2, and D3 of the light emitting elements 21 in the regions 41, 42, and 43 in the light emitting region 95 according to the eighth example of the embodiment. As described above, in this example, since the light emitting elements 21 are randomly arranged to some extent, the intervals D1, D2, and D3 according to this example each have a certain width (error). The maximum value of the distance D1 in the region 41 located closest to the center portion 25 (region relatively located on the center portion 25 side) is the region 42 located relatively second on the center portion 25 side (relatively the outer peripheral portion 26). Smaller than the minimum value of the interval D2 in the region located on the side), and the maximum value of the interval D2 in the region 42 located on the second central portion 25 side (region located relatively on the central portion 25 side) It is preferable to be smaller than the minimum value of the distance D3 in the region 43 located on the portion 26 side (region relatively located on the outer peripheral portion 26 side). For example, when the constants d1, d2, d3, and d4 have a relationship of d1 <d2 <d3 <d4, the interval D1 satisfies d1 ≦ D1 <d2, the interval D2 satisfies d2 ≦ D2 <d3, and the interval D3 is d3. It is preferable to satisfy ≦ D3 <d4. By satisfying such a relationship, even if the intervals D1, D2, and D3 in the regions 41, 42, and 43 have a certain width, the light emitting region 95 as a whole has the intervals D1, D2, and D3 at the center. The relationship of gradually increasing from the portion 25 toward the outer peripheral portion 26 can be maintained, and the uniformity of light intensity in the light emitting region 95 can be improved.

  Below, the usage example of the said surface emitting laser array 1 is shown. FIG. 19 is a diagram schematically illustrating a configuration of a main part of the engine 101 according to the embodiment.

  The engine 101 includes an ignition device 111, a fuel injection mechanism 112, an exhaust mechanism 113, a combustion chamber 114, and a piston 115.

The outline of the operation of the engine 101 is as follows.
(1) The fuel ejection mechanism 112 ejects a combustible mixture of fuel and air into the combustion chamber 114 (intake).
(2) The piston 115 rises and compresses the combustible air-fuel mixture (compression).
(3) The ignition device 111 emits laser light into the combustion chamber 114. Thereby, the fuel is ignited (ignition).
(4) Combustion gas is generated and the piston 115 descends (combustion).
(5) The exhaust mechanism 113 exhausts the combustion gas to the outside of the combustion chamber 114 (exhaust).

  Thus, a series of processes consisting of intake, compression, ignition, combustion, and exhaust are repeated. Then, the piston 115 moves corresponding to the volume change of the gas in the combustion chamber 114 to generate kinetic energy. For example, natural gas, gasoline or the like is used as the fuel.

  The engine 101 performs the above operation based on a control signal output from the control device. The control device is a unit including, for example, a CPU (Central Processing Unit) and the like. The control device is provided outside the engine 101 and is electrically connected to the engine 101.

  FIG. 20 is a diagram illustrating a configuration of the ignition device 111 according to the embodiment. The ignition device 111 includes a laser device 201, an emission optical system 202, and a protection member 203. The ignition device 111 is driven by a current supplied from the drive device 301. The driving device 301 is controlled by a control signal output from the control device 302.

  The emission optical system 202 condenses the laser light emitted from the laser device 201. Thereby, a high energy density can be obtained at the condensing point.

  The protection member 203 is a transparent window provided facing the combustion chamber 114. As a material for the protective member 203, sapphire glass or the like can be used.

  The laser device 201 includes a surface emitting laser array 1, a first optical system 211, an optical fiber 212 (transmission member), a second optical system 213, and a laser resonator 214. Here, the description will be made assuming that the emission direction of the light emitted from the surface emitting laser array 1 is the + Z direction, using an XYZ three-dimensional orthogonal coordinate system.

  The surface emitting laser array 1 is used as an excitation light source. The wavelength of the light emitted from the surface emitting laser array 1 is, for example, 808 nm.

  The surface-emitting laser array 1 is a light source that is advantageous for exciting a Q-switched laser whose characteristics greatly change due to the displacement of the excitation wavelength because the wavelength shift of light due to temperature is very small. By using the surface emitting laser array 1 as an excitation light source, there is an advantage that the mechanism for controlling the environmental temperature can be simplified.

  The first optical system 211 includes an optical element that condenses the light emitted from the surface emitting laser array 1. The light collected by the first optical system 211 enters the optical fiber 212.

  The optical fiber 212 is arranged so that the center of the end surface on the −Z side of the core is located at a position where light is collected by the first optical system 211. As the optical fiber 212, for example, an optical fiber having a core diameter of 1.5 mm and an NA (Numerical Aperture) of 0.39 can be used.

  By providing the optical fiber 212, the surface emitting laser array 1 can be installed at a position away from the laser resonator 214. Thereby, the freedom degree of design improves. Further, when the laser device 201 is used as a part of the ignition device 111, the surface emitting laser array 1 can be moved away from the heat source (for example, the combustion chamber 114). Therefore, the types of cooling mechanisms of the engine 101 that can be employed increase.

  The light incident on the optical fiber 212 propagates in the core and is emitted from the + Z side end face of the core.

  The second optical system 213 includes an optical element that collects light emitted from the optical fiber 212. The light condensed by the second optical system 213 enters the laser resonator 214.

  The laser resonator 214 is a Q-switched laser that resonates and amplifies the light emitted from the second optical system 213. FIG. 21 is a diagram illustrating a configuration of the laser resonator 214 according to the embodiment. The laser resonator 214 includes a laser medium 221 and a saturable absorber 222.

  The laser medium 221 is, for example, a rectangular parallelepiped Nd: YAG crystal having a size of 3 mm × 3 mm × 8 mm, and may be Nd doped 1.1%. The saturable absorber 222 is, for example, a 3 mm × 3 mm × 2 mm cuboidal Cr: YAG crystal, and may have an initial transmittance of 30%.

  The Nd: YAG crystal and the Cr: YAG crystal are joined and may constitute a so-called composite crystal. Both Nd: YAG crystal and Cr: YAG crystal are ceramics.

  The light emitted from the second optical system 213 enters the laser medium 221. That is, the laser medium 221 is excited by the light emitted from the second optical system 213. The wavelength of the light emitted from the surface emitting laser array 1 is the wavelength with the highest absorption efficiency in the YAG crystal. The saturable absorber 222 operates as a Q switch.

  The incident side (−Z side) surface (first surface 225) of the laser medium 221 and the exit side (+ Z side) surface (second surface 226) of the saturable absorber 222 are subjected to an optical polishing process. Acts as a mirror.

  The first surface 225 and the second surface 226 are coated with a dielectric film corresponding to the wavelength of light emitted from the surface emitting laser array 1 and the wavelength of light emitted from the laser resonator 214.

  For example, the first surface 225 is coated with 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. The The second surface 226 is coated with a reflectivity of 50% for light having a wavelength of 1064 nm.

  Thereby, the light resonates and is amplified in the laser resonator 214. The resonator length of the laser resonator 214 is, for example, 10 (= 8 + 2) mm.

  As shown in FIG. 20, the drive device 301 drives the surface emitting laser array 1 based on a control signal from the control device 302. That is, the drive device 301 drives the surface emitting laser array 1 so that light is emitted from the ignition device 111 at the timing of ignition in the operation of the engine 101. The plurality of light emitting elements in the surface emitting laser array 1 may be turned on and off simultaneously.

  Note that the optical fiber 212 may not be provided when the surface emitting laser array 1 does not need to be placed at a position away from the laser resonator 214.

  In addition, each of the first optical system 211, the second optical system 213, and the emission optical system 202 may be configured by a single optical element (lens or the like), or may be configured by a plurality of optical elements. Also good.

  In the above description, the engine 101 (piston engine) that moves the piston 115 with combustion gas has been described. However, the configuration of the internal combustion engine using the laser device 201 (ignition device 111) is not limited thereto. The laser device 201 can be employed in an internal combustion engine having any configuration that burns fuel to generate combustion gas, and can be applied to, for example, a rotary engine, a gas turbine engine, a jet engine, and the like. Further, the laser device 201 may be used for cogeneration, which is a system that uses exhaust heat to extract power, warm heat, cold heat, and the like to improve energy efficiency comprehensively.

  Further, the laser device 201 can be applied to other than the internal combustion engine, and may be used for, for example, a laser processing machine, a laser peening device, a terahertz generator, and the like.

  Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Surface emitting laser array 11 Semiconductor substrate 12 Upper electrode 13 Lower electrode 14, 50, 60, 70, 80, 90, 93, 95 Light emission area 21 Light emitting element 22 Laser beam 25 Center part 26 Outer part 31, 32 Reflective layer 33 Active Layer 34 Selective oxidation layer 35 Contact layer 37 Outlet 41 First region 42 Second region 43 Third region 44 Fourth region 51 Submount 61 Substrate 62 Substrate 62 Anode film 63 Cathode film 64 Anode rod 65 Cathode rod 71 Bonding Wire 101 Engine 111 Ignition device 112 Fuel injection mechanism 113 Exhaust mechanism 114 Combustion chamber 115 Piston 201 Laser device 211 First optical system 212 Optical fiber 213 Second optical system 214 Laser resonator 221 Laser medium 222 Saturable absorber 225 First First surface 226 Second surface 301 Braking system 302 controller Dx, Dy, D1, D2, D3, D4 (the light-emitting element 21) spacing S1 unit area

Japanese Patent No. 5224159

Claims (14)

A light emitting region in which a plurality of surface emitting laser elements are disposed;
A current path for supplying current from the outer periphery of the light emitting region to the surface emitting laser element;
With
The interval between the plurality of surface emitting laser elements is larger on the outer peripheral side than on the central side of the light emitting region,
Surface emitting laser array. The interval gradually increases from the central portion toward the outer peripheral portion,
The surface emitting laser array according to claim 1. The light emitting region includes three or more regions having different intervals.
The surface emitting laser array according to claim 2. The spacing in one of the regions is constant;
The surface emitting laser array according to claim 3. The spacing in one of the regions has a width;
The maximum value of the interval in the region relatively located on the central portion side is smaller than the minimum value of the interval in the region relatively located on the outer peripheral portion side,
The surface emitting laser array according to claim 3. The light emitting region has a point-symmetric shape with the central portion as a symmetric point.
The surface emitting laser array of any one of Claims 1-5. The light emitting area is circular,
The surface emitting laser array according to claim 6. The light emitting area is polygonal.
The surface emitting laser array according to claim 6. The current path includes a common positive electrode to which the plurality of surface emitting laser elements are connected.
The surface emitting laser array of any one of Claims 1-8. The current path includes a common negative electrode to which the plurality of surface emitting laser elements are connected.
The surface emitting laser array of any one of Claims 1-9. A surface emitting laser array according to any one of claims 1 to 10,
An optical system for collecting the light emitted from the surface emitting laser array;
A laser resonator for resonating the collected light;
A laser apparatus comprising: A member for transmitting the light, and a transmission member disposed between the surface emitting laser array and the laser resonator;
The laser device according to claim 11, further comprising: The optical system includes a first optical system including an optical element that collects light emitted from the surface emitting laser array and incident on the transmission member,
The laser device according to claim 12. The optical system includes a second optical system including an optical element that collects light transmitted to the transmission member and incident on the laser resonator.
The laser device according to claim 12 or 13.

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