JP2017216285A - Surface emitting laser array device, light source unit, and laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface emitting laser array device capable of improving uniformity of a potential distribution in a light emitting region.SOLUTION: The surface emitting laser array device includes a light emitting region in which a plurality of surface emitting lasers are electrically connected in parallel by a metal film. An insulating film is included in the metal film of a part of the light emitting region.SELECTED DRAWING: Figure 1

Description

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

  A surface emitting laser (VCSEL: Vertical Cavity Surface Emitting LASER) is a semiconductor laser that emits light in a direction perpendicular to a substrate surface. The surface emitting laser has features such as low cost, low power consumption, small size, high performance, and easy integration in two dimensions, compared to the edge emitting semiconductor laser. There is also known a surface emitting laser array element in which a plurality of surface emitting lasers are two-dimensionally arranged and a plurality of surface emitting lasers are electrically connected in parallel by a metal film.

  Since the optical output of such a surface emitting laser array element is proportional to the number of surface emitting lasers, when a high output surface emitting laser array element is required, a plurality of surface emitting lasers are increased over the entire light emitting region. Arrange for density.

  However, when a plurality of surface emitting lasers are arranged at a high density, an unbalanced temperature distribution is generated in the light emitting region of the surface emitting laser array element, and there is a possibility that the light output and life of each surface emitting laser vary.

  Therefore, conventionally, a surface emitting laser is provided by arranging a surface emitting laser in a region other than the central portion of the light emitting region, or by changing the mesa shape between a region where the temperature rise of the light emitting region is high and a region where the temperature rises is low. Variation in the light output and life of the light is reduced (see, for example, Patent Documents 1 and 2).

  However, in a surface-emitting laser array element that requires a large current, an unbalanced potential distribution occurs in the light-emitting region, and the output and life of the surface-emitting laser may vary. This is because the wiring member is connected to the outer peripheral portion of the metal film provided in the light emitting region, and a voltage is applied to a plurality of surface emitting lasers in the light emitting region. This is because an unbalanced potential distribution occurs in which the potential decreases toward the target.

  Thus, when an unbalanced potential distribution is generated in which the potential decreases from the outer periphery to the center of the light emitting region, the surface on which the driving current of the surface emitting laser disposed at the center of the light emitting region is disposed at the outer periphery. It becomes smaller than the drive current of the light emitting laser. For this reason, the light output of the surface emitting laser disposed in the central portion of the light emitting region is smaller than the light output of the surface emitting laser disposed in the outer peripheral portion, and the uniformity of the light output is deteriorated.

  In view of the above problems, an object of the present invention is to provide a surface emitting laser array element capable of improving the uniformity of potential distribution in the light emitting region.

  In order to achieve the above object, a surface emitting laser array element according to an aspect of the present invention includes a light emitting region in which a plurality of surface emitting lasers are electrically connected in parallel by a metal film, and a part of the light emitting region is provided. The metal film includes an insulating film.

  According to the disclosed technology, it is possible to provide a surface emitting laser array element capable of improving the uniformity of the potential distribution in the light emitting region.

Schematic of the surface emitting laser array element of the first embodiment Schematic sectional view of a conventional surface emitting laser array element The figure for demonstrating the other example of the light emission area | region in the surface emitting laser array element of FIG. Schematic sectional view of a surface emitting laser in the surface emitting laser array element of FIG. Schematic sectional view showing another example of the surface emitting laser in the surface emitting laser array element of FIG. Process drawing (1) of the manufacturing method of the surface emitting laser of 1st Embodiment Process drawing of the manufacturing method of the surface emitting laser of 1st Embodiment (2) Process drawing of the manufacturing method of the surface emitting laser of 1st Embodiment (3) Process drawing of the manufacturing method of the surface emitting laser of 1st Embodiment (4) Process drawing of the manufacturing method of the surface emitting laser of 1st Embodiment (5) Process drawing of the manufacturing method of the surface emitting laser of 1st Embodiment (6) Process drawing of the manufacturing method of the surface emitting laser of 1st Embodiment (7) Process drawing of the manufacturing method of the surface emitting laser of 1st Embodiment (8) Schematic configuration diagram of the laser device of the second embodiment Schematic configuration diagram of ignition device of third embodiment The figure for demonstrating the laser resonator in the ignition device of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[First Embodiment]
(Surface emitting laser array element)
The surface emitting laser array element according to the first embodiment will be described. FIG. 1 is a schematic view of the surface emitting laser array element of the first embodiment. FIG. 1A is a top view of the surface emitting laser array element, FIG. 1B is a cross-sectional view taken along the alternate long and short dash line 1A-1B in FIG. 1A, and FIG. It is a figure for demonstrating an area | region.

  In the surface emitting laser array element 100, a metal film pattern 102, a lower electrode 213, a surface emitting laser array 103, an upper electrode 211, and an insulating film 212 are formed on a heat sink 101. When a voltage is applied between the upper electrode 211 and the lower electrode 213, a voltage is applied to the surface emitting laser array 103, and laser light is emitted.

  The heat sink 101 is formed of an insulating material such as aluminum nitride (AlN).

  The metal film pattern 102 is formed on the upper surface of the heat sink 101. The metal film pattern 102 is a wiring for supplying a current to the surface emitting laser array 103, and includes a p-side region 102p and an n-side region 102n. The p-side region 102p is a region connected to the positive (+) electrode terminal, and the n-side region 102n is a region connected to the negative (−) electrode terminal.

  The lower electrode 213 is bonded onto the n-side region 102 n of the metal film pattern 102 by the bonding agent 104. As the bonding agent 104, a conductive material can be used. For example, a material containing a gold-tin (AuSn) alloy or a material containing silver (Ag) or indium (In) can be used.

  The surface emitting laser array 103 is formed on the upper surface of the lower electrode 213. The surface emitting laser array 103 includes a plurality (for example, several thousand to several tens of thousands) of surface emitting lasers 200 arranged two-dimensionally, and a region where the plurality of surface emitting lasers 200 are arranged forms a light emitting region LA. ing. Details of the surface emitting laser 200 will be described later.

  The upper electrode 211 includes a first upper electrode 211a and a second upper electrode 211b. The first upper electrode 211a is formed on the upper surface of the surface emitting laser array 103 and functions as a common electrode that electrically connects the plurality of surface emitting lasers 200 in parallel. The second upper electrode 211b is formed on the first upper electrode 211a so as to be in contact with the first upper electrode 211a or not to be in contact with the first upper electrode 211a through the insulating film 212. Has been. The second upper electrode 211b is electrically connected to the p-side region 102p of the metal film pattern 102 by the bonding wire 105 at the outer peripheral portion of the light emitting region LA.

  As shown in FIG. 1C, the light emitting area LA includes a first area S11 and a second area S12. 1st area | region S11 is formed in the outer peripheral part containing the position where the bonding wire 105 is connected. The second region S12 is formed in a rectangular shape so as to be sandwiched between the first regions S11 in one direction (Y direction).

  As shown in FIG. 1B, the first region S11 is a region in which an insulating film 212 is formed between the first upper electrode 211a and the second upper electrode 211b. The upper electrode 211a and the second upper electrode 211b are electrically insulated by the insulating film 212. That is, in the first region S11, the first upper electrode 211a, the insulating film 212, and the second upper electrode 211b are stacked in this order. In contrast, the second region S12 is a region where the insulating film 212 is not formed between the first upper electrode 211a and the second upper electrode 211b, and the first upper electrode 211a and the second upper electrode 211b The upper electrode 211b is electrically connected. Thereby, the current supplied to the second upper electrode 211b in the outer peripheral portion of the light emitting region LA flows through the second upper electrode 211b in the second region S12. Then, in the first region S11, it flows from the second upper electrode 211b to the first upper electrode 211a and is supplied to a plurality of surface emitting lasers.

  By the way, when a voltage is applied to the outer peripheral portion of the light emitting region and current is supplied to the plurality of surface emitting lasers via the upper electrodes formed on the upper surfaces of the plurality of surface emitting lasers, The potential decreases from the outer periphery toward the center. In particular, in a surface emitting laser array element that requires a large current (for example, several hundred amperes), the effect of a decrease in potential due to the resistance of the upper electrode becomes large. Thus, when an unbalanced potential distribution is generated in which the potential decreases from the outer periphery to the center of the light emitting region, the surface on which the driving current of the surface emitting laser disposed at the center of the light emitting region is disposed at the outer periphery. It becomes smaller than the drive current of the light emitting laser. For this reason, the light output of the surface emitting laser disposed in the central portion of the light emitting region is smaller than the light output of the surface emitting laser disposed in the outer peripheral portion, and the uniformity of the light output is deteriorated. In addition, since the surface emitting laser disposed in the outer peripheral portion of the light emitting region has a larger load than the surface emitting laser disposed in the central portion, the life of each of the plurality of surface emitting lasers varies.

  Therefore, in the surface emitting laser array element 100 of the present embodiment, the first upper electrode 211a and the second upper electrode 211b in the first region S11 including the portion where the bonding wire 105 is connected in the light emitting region LA. An insulating film 212 is formed between them. Thereby, compared with the case where the insulating film 212 is not formed in the upper electrode 211 (see FIG. 2), the position where the upper electrode 211 and the surface emitting laser array 103 are electrically connected is the light emitting region LA. Approach the center. For this reason, the uniformity of the potential distribution in the light emitting region LA is improved. As a result, the uniformity of the optical output of the laser light emitted from the surface emitting laser array element 100 in the light emitting area LA is improved. In addition, since the variation in current supplied to each of the plurality of surface emitting lasers 200 in the light emitting region LA is reduced, the variation in the lifetime of each surface emitting laser 200 can be reduced. FIG. 2 is a schematic sectional view of a conventional surface emitting laser array element.

  Next, another example of the light emitting region LA in the surface emitting laser array element 100 of FIG. 1 will be described. FIG. 3 is a view for explaining another example of the light emitting region in the surface emitting laser array element of FIG.

  As shown in FIG. 3A, the light emitting area LA may include a first area S21 and a plurality of separated second areas S221, S222, and S223. 1st area | region S21 is formed in the outer peripheral part containing the position where the bonding wire 105 in the light emission area | region LA is connected. Similar to the second region S12, the second region S221 is formed in a rectangular shape so as to be sandwiched between the first regions S21. The second region S222 and the second region S223 are each formed in a circular shape so as to be surrounded by the first region S21 between the second region S221 and the corner of the light emitting region LA. Thus, when the light emitting region LA includes the first region S21 and the plurality of second regions S221, S222, S223, the second upper electrode 211b in the plurality of second regions S221, S222, S223. Current flows through the first upper electrode 211a. For this reason, the potential distribution between the central portion and the outer peripheral portion of the light emitting region LA is smaller than in the case of FIG. More specifically, in the case of FIG. 1A, the potential drop at the central portion of the light emitting region LA is reduced, but the potential drop near the outer peripheral portion of the light emitting region LA may increase. On the other hand, in the case of FIG. 3A, the current path from the second upper electrode 211b to the first upper electrode 211a is also formed near the outer periphery of the light emitting region LA. The potential distribution between the central portion and the outer peripheral portion can be made smaller.

  Further, as shown in FIG. 3B, the light emitting area LA may include a plurality of separated first areas S311, S312, and S313, and a second area S32. The first regions S311, S312, and S313 are formed on the outer peripheral portion including the position where the bonding wire 105 is connected in the light emitting region LA. The second region S32 is formed so as to divide the plurality of first regions S311, S312 and S313. Similar to the second region S12, the second region S32 includes a region formed in a rectangular shape, and a region extending from the region formed in the rectangular shape in a direction toward the corner of the light emitting region LA. When the second region S32 includes a region formed in a rectangular shape and a region extending from the region formed in the rectangular shape in a direction toward the corner of the light emitting region LA, in these regions, A current flows from the second upper electrode 211b to the first upper electrode 211a. For this reason, the potential distribution between the central portion and the outer peripheral portion of the light emitting region LA is smaller than in the case of FIG. More specifically, in the case of FIG. 1A, the potential drop at the central portion of the light emitting region LA is reduced, but the potential drop near the outer peripheral portion of the light emitting region LA may increase. On the other hand, in the case of FIG. 3B, the current path from the second upper electrode 211b to the first upper electrode 211a is also formed near the outer periphery of the light emitting region LA. The potential distribution between the central portion and the outer peripheral portion can be made smaller.

  Further, as shown in FIG. 3C, the light emitting area LA may include a first area S41 and a second area S42. The first region S41 is formed on the outer peripheral portion including the position where the bonding wire 105 is connected in the light emitting region LA. The second region S42 is formed in a circular shape so as to be surrounded by the first region S41. Also in this case, the upper electrode 211 and the surface emitting laser array 103 are electrically connected to each other as compared with the case where the insulating film 212 is not formed between the first upper electrode 211a and the second upper electrode 211b. The connected position approaches the center of the light emitting area LA. For this reason, the uniformity of the potential distribution in the light emitting region LA is improved.

(Surface emitting laser)
Next, the surface emitting laser of this embodiment will be described. FIG. 4 is a schematic sectional view of a surface emitting laser in the surface emitting laser array element of FIG. FIG. 4A shows a surface emitting laser arranged in the first region S11, and FIG. 4B shows a surface emitting laser arranged in the boundary portion between the first region S11 and the second region S12. FIG. 4C shows a surface emitting laser arranged in the second region S12. 4 (a), 4 (b), and 4 (c), only one surface emitting laser among a plurality of surface emitting lasers is shown for convenience, but other surface emitting lasers are also shown. It can be set as the same structure. In FIG. 4, the direction in which the laser light is emitted is the upward direction.

  First, the surface emitting laser disposed in the first region S11 will be described.

  As shown in FIG. 4A, the surface emitting laser 200a has an oscillation wavelength in the 808 nm band, for example, and includes a substrate 201, a buffer layer 202, a lower Bragg reflector 203, a lower spacer layer 204, an active layer 205, and an upper spacer. A layer 206, an upper Bragg reflector 207, a current confinement layer 208, a contact layer 209, a protective film 210, an upper electrode 211, an insulating film 212, a lower electrode 213, and the like. In this embodiment, it is assumed that the Bragg reflector includes a DBR (Distributed Bragg Reflector). The oscillation wavelength is not limited to the 808 nm band, and can be selected according to the application.

  The substrate 201 is formed of an n-GaAs substrate that is an n-type semiconductor.

  The buffer layer 202 is laminated on the upper surface of the substrate 201 and is formed of n-GaAs.

The lower Bragg reflector 203 is stacked on the upper surface of the buffer layer 202. The lower Bragg reflector 203 includes a low refractive index layer formed of n-Al _0.9 Ga _0.1 As and a high refractive index layer formed of n-Al _0.3 Ga _0.7 As. Starting from Al _0.9 Ga _0.1 As, 40.5 pairs are alternately stacked. Between the low refractive index layer and the high refractive index layer, a composition gradient layer in which the composition is gradually changed from one composition to the other composition may be provided. By providing the composition gradient layer, the electrical resistance can be reduced. The low-refractive index layer and the high-refractive index layer include half of the thickness of the adjacent composition gradient layer, and are designed so that the optical thickness is λ / 4 with respect to the oscillation wavelength λ. When the optical film 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 lower spacer layer 204 is laminated on the upper surface of the lower Bragg reflector 203 and is formed of non-doped Al _0.6 Ga _0.4 As.

The active layer 205 is stacked on the upper surface of the lower spacer layer 204. The active layer 205 has a triple quantum well structure (TQW: Triple) formed by alternately stacking three pairs of Al _0.05 Ga _0.95 As quantum well layers and Al _0.3 Ga _0.7 As barrier layers. Quantum Well). The active layer 205 may have a multi quantum well (MQW) structure other than the triple quantum well structure.

The upper spacer layer 206 is laminated on the upper surface of the active layer 205 and is formed of non-doped Al _0.6 Ga _0.4 As. The upper spacer layer 206 is designed so that the oscillation wavelength is 808 nm.

  In the surface emitting laser of this embodiment, a resonator region having an optical length of one wavelength is formed by the lower spacer layer 204, the active layer 205, and the upper spacer layer 206. The active layer 205 is provided at the center of the resonator region, which is a position corresponding to the antinode in the standing wave distribution of the electric field, so that a high stimulated emission probability can be obtained.

The upper Bragg reflector 207 is laminated on the upper surface of the upper spacer layer 206, and is formed of a low refractive index layer formed of p-Al _0.9 Ga _0.1 As and p-Al _0.3 Ga _0.7 As. 25 pairs of high refractive index layers are alternately stacked. Between the low refractive index layer and the high refractive index layer, a composition gradient layer in which the composition is gradually changed from one composition to the other composition may be provided. By providing the composition gradient layer, the electrical resistance can be reduced. The low refractive index layer and the high refractive index layer are designed such that the optical film thickness is λ / 4 with respect to the oscillation wavelength λ, including ½ of the film thickness of the adjacent composition gradient layer. In one of the low refractive index layers in the upper Bragg reflector 207, a current confinement layer 208 made of AlAs is inserted with a thickness of, for example, 30 nm. Note that the thickness of the current confinement layer 208 is not limited to 30 nm.

  The current confinement layer 208 includes a selective oxidation region 208a formed by selective oxidation from the periphery of a mesa described later, and a current confinement region 208b, which is a central region of the mesa not selectively oxidized.

  The contact layer 209 is laminated on the upper surface of the upper Bragg reflector 207 and is made of p-GaAs.

  Note that a structure in which a plurality of semiconductor layers are stacked on the substrate 201 in this manner is also referred to as a “stacked body” for convenience in the following. On the substrate 201, a mesa is formed by removing a part of the contact layer 209, the current confinement layer 208, the upper Bragg reflector 207, the upper spacer layer 206, the active layer 205, and the lower spacer layer 204. .

The protective film 210 is laminated on the side surface of the mesa and the upper surface of the region from which the semiconductor material has been removed when forming the mesa, and is formed of an insulating material such as SiN, SiON, or SiO ₂ . In the protective film 210, an opening A1 is formed on the top surface of the mesa.

  The upper electrode 211 is a p-side electrode including a first upper electrode 211a and a second upper electrode 211b. The first upper electrode 211a is laminated on the upper surface of the outer peripheral contact layer 209 and the upper surface of the protective film 210 on the upper surface of the mesa, and is formed of a Ti / Pt / Au laminated film. The first upper electrode 211a has an opening A2 on the top surface of the mesa. The second upper electrode 211b is laminated on the first upper electrode 211a via an insulating film 212, and is formed of a Ti / Pt / Au laminated film. An opening A4 is formed in the upper surface of the mesa in the second upper electrode 211b.

The insulating film 212 is formed between the first upper electrode 211a and the second upper electrode 211b. Insulating film 212, SiN, SiON, is formed of an insulating material such as SiO _2. In the insulating film 212, an opening A3 is formed on the top surface of the mesa.

  In the example of FIG. 4A, the opening diameter D2 of the opening A2 of the first upper electrode 211a, the opening diameter D3 of the opening A3 of the insulating film 212, and the opening A4 of the second upper electrode 211b are opened. The diameter D4 is the same.

  The lower electrode 213 is laminated on the lower surface of the substrate 201 and is formed of an AuGe / Ni / Au laminated film. The lower electrode 213 is an n-side electrode.

  As described above, in the surface emitting laser 200a disposed in the first region S11, the insulating film 212 is formed between the first upper electrode 211a and the second upper electrode 211b.

  Next, the surface emitting laser arranged at the boundary between the first region S11 and the second region S12 will be described. Unlike the surface emitting laser 200a, the surface emitting laser 200b disposed at the boundary between the first region S11 and the second region S12 is insulated between the first upper electrode 211a and the second upper electrode 211b. It has a portion where the film 212 is formed and a portion where the film 212 is not formed. Hereinafter, a description will be given focusing on differences from the surface emitting laser 200a disposed in the first region S11.

  As shown in FIG. 4B, the surface emitting laser 200b has an oscillation wavelength of 808 nm, and includes a substrate 201, a buffer layer 202, a lower Bragg reflector 203, a lower spacer layer 204, an active layer 205, and an upper spacer layer. 206, an upper Bragg reflector 207, a current confinement layer 208, a contact layer 209, a protective film 210, an upper electrode 211, an insulating film 212, a lower electrode 213, and the like.

  Substrate 201, buffer layer 202, lower Bragg reflector 203, lower spacer layer 204, active layer 205, upper spacer layer 206, upper Bragg reflector 207, current confinement layer 208, contact layer 209, protective film 210, and lower electrode 213 Can have the same configuration as the surface emitting laser 200a.

  The upper electrode 211 is a p-side electrode including a first upper electrode 211a and a second upper electrode 211b. The first upper electrode 211a is laminated on the upper surface of the outer peripheral contact layer 209 and the upper surface of the protective film 210 on the upper surface of the mesa, and is formed of a Ti / Pt / Au laminated film. The second upper electrode 211b is laminated on the first upper electrode 211a via the insulating film 212 or without the insulating film 212, and is formed of a Ti / Pt / Au laminated film. . That is, the second upper electrode 211b is electrically insulated from the first upper electrode 211a by being formed on the upper surface of the insulating film 212 in a partial region (first region S11). The second upper electrode 211b is electrically connected to the first upper electrode 211a by being stacked on the upper surface of the first upper electrode 211a in another region (second region S12).

Insulating film 212 is stacked on a part of the upper surface of the first upper electrode 211a, SiN, SiON, is formed of an insulating material such as SiO _2.

  Next, the surface emitting laser 200c disposed in the second region S12 will be described. The surface emitting laser 200c disposed in the second region S12 is different from the surface emitting laser 200a in that the insulating film 212 is not formed between the first upper electrode 211a and the second upper electrode 211b. Hereinafter, a description will be given focusing on differences from the surface emitting laser 200a disposed in the first region S11.

  As shown in FIG. 4C, the surface emitting laser 200c has an oscillation wavelength in the 808 nm band, the substrate 201, the buffer layer 202, the lower Bragg reflector 203, the lower spacer layer 204, the active layer 205, and the upper spacer layer. 206, an upper Bragg reflector 207, a current confinement layer 208, a contact layer 209, a protective film 210, an upper electrode 211, a lower electrode 213, and the like.

  Substrate 201, buffer layer 202, lower Bragg reflector 203, lower spacer layer 204, active layer 205, upper spacer layer 206, upper Bragg reflector 207, current confinement layer 208, contact layer 209, protective film 210, and lower electrode 213 Can have the same configuration as the surface emitting laser 200a.

  The upper electrode 211 is a p-side electrode including a first upper electrode 211a and a second upper electrode 211b. The first upper electrode 211a is laminated on the upper surface of the outer peripheral contact layer 209 and the upper surface of the protective film 210 on the upper surface of the mesa, and is formed of a Ti / Pt / Au laminated film. The second upper electrode 211b is laminated on the upper surface of the first upper electrode 211a, and is formed of a Ti / Pt / Au laminated film. That is, the second upper electrode 211b is electrically connected to the first upper electrode 211a by being stacked on the upper surface of the first upper electrode 211a.

  Next, a modification of the surface emitting laser arranged in the first region S11 will be described. FIG. 5 is a schematic sectional view showing another example of the surface emitting laser in the surface emitting laser of FIG.

  As shown in FIG. 5A, the surface emitting laser 200d of the modification is different from the surface emitting laser 200a described above, and the opening diameter D4 of the opening A4 of the second upper electrode 211b is the opening of the insulating film 212. It is larger than the opening diameter D3 of the part A3. Thereby, it is possible to suppress the first upper electrode 211a and the second upper electrode 211b from being electrically short-circuited through the inner surface of the opening A3 of the insulating film 212 in the first region S11. The same configuration may be applied to the surface emitting laser arranged at the boundary between the first region S11 and the second region S12.

  Further, as shown in FIG. 5B, the surface emitting laser 200e of the modified example is different from the surface emitting laser 200a described above in that no opening is formed in the insulating film 212. That is, the insulating film 212 is formed so as to cover the contact layer 209. Thereby, it is possible to suppress an electrical short circuit between the first upper electrode 211a and the second upper electrode 211b in the first region S11. In addition, since the opening portion need not be formed in the insulating film 212, the manufacturing process can be shortened. The same configuration may be applied to the surface emitting laser arranged at the boundary between the first region S11 and the second region S12.

(Manufacturing method of surface emitting laser array element)
Next, a method for manufacturing the surface emitting laser array element of the present embodiment will be described by taking as an example the case of manufacturing the surface emitting laser shown in FIG.

(1) As shown in FIG. 6, on a substrate 201, a buffer layer 202, a lower Bragg reflector 203, a lower spacer layer 204, an active layer 205, an upper spacer layer 206, an upper Bragg reflector 207, and a current confinement layer. 208 and a semiconductor layer including the contact layer 209 are stacked to form a stacked body. The semiconductor layer is formed by a metal organic chemical vapor deposition (MOCVD) method, a molecular beam epitaxy (MBE) method, or the like. Note that trimethylaluminum (TMA) and trimethylgallium (TMG) can be used as Group III materials, and arsine (AsH ₃ ) can be used as Group V materials. Carbon tetrabromide (CBr ₄ ) can be used as a p-type dopant material, and hydrogen selenide (H ₂ Se) can be used as an n-type dopant material.

  (2) A photoresist is applied to the upper surface of the contact layer 209, and exposure and development are performed by an exposure apparatus, thereby forming a square resist pattern having a side of 25 μm corresponding to a desired mesa shape in an array. .

  (3) Using the resist pattern as an etching mask, the semiconductor layer in the region where the resist pattern is not formed is removed by dry etching until the side surface of the current confinement layer 208 is exposed to form a square column mesa. As the dry etching, for example, dry etching using inductively coupled plasma (ICP) can be used. Thereafter, the resist pattern is removed. On the side surface of the mesa thus formed, the side surface of the upper Bragg reflector 207 is exposed. The shape on the upper surface of the mesa may be, for example, a circle, an ellipse, a rectangle, or any other shape.

  (4) As shown in FIG. 7, the AlAs film, which is the current confinement layer 208 exposed on the side surface of the mesa, is heat-treated in water vapor and oxidized from the periphery to form AlxOy, thereby forming the selective oxidation region 208a. Form. As a result, a region that is not selectively oxidized in the current confinement layer 208 becomes a current confinement region 208b, and a current confinement (oxidation aperture) structure that restricts the drive current path of the light emitting portion only to the central portion of the mesa is formed.

  (5) A resist pattern is formed by photolithography so that only the outer peripheral groove forming portion is exposed, and a groove is formed by dry etching using ICP. Thereafter, the resist pattern is removed.

  (6) The laminate is placed in a heating container and held in a nitrogen atmosphere at a temperature of 380 to 400 ° C. for 3 minutes. As a result, a natural oxide film formed by oxygen or water adhering to the surface in the atmosphere or a trace amount of oxygen or water in the heating container becomes a stable passive film by heat treatment in a nitrogen atmosphere.

(7) As shown in FIG. 8, a protective film 210 is formed by depositing an insulating material such as SiN, SiON, or SiO ₂ by a chemical vapor deposition (CVD) method.

  (8) An opening for electrically connecting the contact layer 209 and the first upper electrode 211a is formed on the upper surface of the protective film 210 by applying a photoresist and performing exposure and development with an exposure apparatus. A resist pattern corresponding to the position to be formed is formed. Thereafter, using the resist pattern as an etching mask, the protective film 210 in the region where the resist pattern is not formed is removed with buffered hydrofluoric acid (BHF) until the upper surface of the contact layer 209 is exposed, thereby forming an opening A1. Thereafter, by removing the resist pattern, a protective film 210 having an opening A1 is formed as shown in FIG.

  (9) By applying a photoresist on the upper surface of the contact layer 209 and the protective film 210, and performing exposure and development by an exposure apparatus, a square resist having a side of 10 μm in a region to be a light emitting portion on the top of the mesa Form a pattern. Thereafter, a Ti / Pt / Au laminated film is formed by vacuum deposition.

  (10) Lift-off is performed by performing ultrasonic cleaning in an organic solvent such as acetone, and as shown in FIG. 10, the first upper electrode 211a having an opening A2 is formed in a region to be a light emitting portion. .

(11) An insulating film 212 is formed by depositing an insulating material such as SiN, SiON, or SiO _{2 on} the upper surface of the first upper electrode 211a and the upper surface of the contact layer 209 by CVD.

  (12) As shown in FIG. 11, the insulating film 212 is etched by the same method as in the above (8) so that the insulating film 212 remains on the outer periphery of the light emitting region LA. At this time, as shown in FIG. 12, in the region where the insulating film 212 remains, the opening A3 is formed at a position corresponding to the opening A2 formed in the first upper electrode 211a in the upper part of the mesa. At this time, since the insulating film 212 is removed in a region where the insulating film 212 does not remain, the upper surface of the first upper electrode 211a is exposed as shown in FIG.

  (13) A square resist pattern having a side of 10 μm is formed in a region to be a light emitting portion on the top of the mesa. Thereafter, a Ti / Pt / Au laminated film is formed by vacuum deposition.

  (14) Lift-off is performed by performing ultrasonic cleaning in an organic solvent such as acetone to form the second upper electrode 211b having the opening A4. Accordingly, in the region where the insulating film 212 remains, the second upper electrode 211a and the second upper electrode 211b are insulated by the insulating film 212 as shown in FIG. An upper electrode 211b is formed. Further, at the boundary portion between the region where the insulating film 212 remains and the region where the insulating film does not remain, as shown in FIG. 13B, the first upper electrode is formed by the insulating film 212 in the region where the insulating film 212 remains. A second upper electrode 211b is formed so as to be electrically insulated from 211a. In addition, the second upper electrode 211b is formed so as to be electrically connected to the first upper electrode 211a in a region where no insulating film remains. Further, in the region where the insulating film 212 does not remain, as shown in FIG. 13C, the second upper electrode 211a and the second upper electrode 211b are electrically connected so that the first upper electrode 211a and the second upper electrode 211b are electrically connected. 211b is formed.

  (15) The back surface of the substrate 201 is polished, and the lower electrode 213 is formed by forming an AuGe / Ni / Au laminated film on the polished back surface by a vacuum deposition method, a sputtering method, or the like. The plate thickness after polishing the substrate 201 can be, for example, 100 μm to 300 μm, and preferably 200 μm.

  (16) The substrate 201 on which the lower electrode 213 is formed is heat-treated to form ohmic contacts between the contact layer 209 and the first upper electrode 211a, and between the substrate 201 and the lower electrode 213, and to make them conductive. .

  By the steps (1) to (16), the surface emitting laser shown in FIGS. 4A, 4B, and 4C can be manufactured.

  (17) Cut by chip by scribing and braking.

  (18) On the hot plate heated to 200 to 250 ° C., the heat radiating plate 101 on which the metal film pattern 102 is formed and the laminate are bonded by the bonding agent 104. As the metal film pattern 102, for example, a pattern formed of Au having a thickness of 1 μm can be used.

  (19) Using the bonding wire 105 formed of Au, the second upper electrode 211b and the p-side region 102p of the metal film pattern 102 are electrically connected.

  The surface emitting laser array element 100 shown in FIG. 1 can be manufactured by the steps (1) to (19).

[Second Embodiment]
In the second embodiment, a laser apparatus having the surface emitting laser array element of the first embodiment will be described. FIG. 14 is a schematic configuration diagram of a laser apparatus according to the second embodiment.

  As shown in FIG. 14, the laser device of this embodiment includes a light source unit 410, a condenser lens 420, and an optical fiber 430. In the laser device, the light emitted from the light source unit 410 is collected by the condenser lens 420, then enters one end of the optical fiber 430, and the laser light is emitted from the other end of the optical fiber 430.

  In the light source unit 410, a surface emitting laser array 412 in which a plurality of surface emitting lasers 411 are two-dimensionally arranged and a plurality of microlenses arranged on the optical path of light emitted from the plurality of surface emitting lasers 411 are arranged. And a two-dimensional microlens array 413. The surface emitting laser array 412 is the surface emitting laser array element of the first embodiment described above. The light emitted from the surface emitting laser array 412 is a laser beam having a radiation angle for each surface emitting laser 411, and becomes parallel light by passing through the microlens array 413. The light that has become parallel light enters the condenser lens 420.

  The condensing lens 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 optical fiber 430 transmits the light collected by the condenser lens 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 condenser lens 420 is incident on the core 431 of the optical fiber 430.

  In the light source unit 410 of the second embodiment, the laser light emitted from the surface emitting laser array element 100 of the first embodiment capable of improving the uniformity of the potential distribution in the light emitting region LA is parallelized by the microlens array 413. Make it light. Thereby, it is possible to output parallel laser light with uniform light output in the plane.

[Third Embodiment]
In the third embodiment, an ignition device having the surface emitting laser array element of the first embodiment will be described. FIG. 15 is a schematic configuration diagram of the ignition device according to the third embodiment. FIG. 16 is a diagram for explaining a laser resonator in the ignition device of FIG.

  As shown in FIG. 15 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 surface emitting laser array 1201, 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 XYZ three-dimensional orthogonal coordinate system is used and the light emission direction from the surface emitting laser array 1201 is described as the + Z direction.

  The surface emitting laser array 1201 is an excitation light source, and has a plurality of light emitting units. The surface emitting laser array 1201 is the surface emitting laser array element of the first embodiment described above. The wavelength of light emitted from the surface emitting laser array 1201 is 808 nm.

  The surface-emitting laser array 1201 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 displacement due to the temperature of the emitted light is very small. Therefore, when the surface emitting laser array 1201 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 surface emitting laser array 1201.

  The optical fiber 1204 is disposed so that the center of the end surface on the −Z side of the core is located at a position where the light is condensed 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 1201 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 for an ignition device, the surface emitting laser array 1201 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. 16 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 1201 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. 16).

  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 1201 and the wavelength of light emitted from the laser resonator 1206. .

  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. In addition, the second surface 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 1206. Here, the resonator length of the laser resonator 1206 is 10 (= 8 + 2) mm.

  Returning to FIG. 15, the drive device 1220 drives the surface emitting laser array 1201 based on an instruction from the engine control device 1222. That is, drive device 1220 drives surface emitting laser array 1201 so that light is emitted from the ignition device at the timing of ignition in engine operation. The plurality of light emitting units in the surface emitting laser array 1201 are turned on and off simultaneously.

  In the above embodiment, when it is not necessary to place the surface emitting laser array 1201 at a position away from the laser resonator 1206, the optical fiber 1204 may not be provided.

  Also, 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, 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.

  Moreover, you may use an ignition device for the cogeneration which is a system which takes out heat, takes out power, heat, and cold, and improves an 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, it can be used for a laser processing machine, a laser peening apparatus, a terahertz generator, and the like.

  In each of the above embodiments, the upper electrode 211 is an example of a metal film, the first upper electrode 211a is an example of a first metal film, and the second upper electrode 211b is an example of a second metal film. It is an example. The bonding wire 105 is an example of a wiring member.

  As mentioned above, although embodiment of this invention was described, the said content does not limit the content of invention, Various deformation | transformation and improvement are possible within the scope of the present invention.

100 surface emitting laser array element 101 heat sink 102 metal film pattern 102p p side region 102n n side region 103 surface emitting laser array 104 bonding agent 105 bonding wire 200 surface emitting laser 201 substrate 202 buffer layer 203 lower Bragg reflector 204 lower spacer layer 205 Active layer 206 Upper spacer layer 207 Upper Bragg reflector 208 Current confinement layer 208a Selective oxidation region 208b Current confinement region 209 Contact layer 210 Protective film 211 Upper electrode 211a First upper electrode 211b Second upper electrode 212 Insulating film 213 Lower Electrode 410 Light source unit 411 Surface emitting laser 412 Surface emitting laser array 413 Microlens array 420 Condensing lens 430 Optical fiber LA Light emitting region S11 First region S12 Second region

JP 2005-216925 A JP 2008-311499 A

Claims (10)

A plurality of surface emitting lasers have a light emitting region electrically connected in parallel by a metal film,
A surface emitting laser array element comprising an insulating film in the metal film in a part of the light emitting region. The light emitting region includes a first region in which the insulating film is provided in the metal film, and a second region in which the insulating film is not provided in the metal film,
The surface emitting laser array element according to claim 1, wherein the second region is surrounded by or sandwiched between the first regions. A wiring member that supplies current to the light emitting region is connected to the metal film,
The surface emitting laser array device according to claim 2, wherein the first region includes a position where the metal film and the wiring member are connected. The metal film is
A first metal film electrically connecting the plurality of surface emitting lasers in parallel;
A second metal film formed on the first metal film;
Have
4. The surface emitting laser array element according to claim 3, wherein the insulating film is formed between the first metal film and the second metal film in the first region. The surface emitting laser is
A lower Bragg reflector formed of a semiconductor material on the substrate;
A resonator region including an active layer formed on the lower Bragg reflector;
An upper Bragg reflector formed of a semiconductor material on the resonator region;
A contact layer formed on the upper Bragg reflector;
Have
The said 1st area | region WHEREIN: The said 1st metal film, the said insulating film, and the said 2nd metal film are laminated | stacked in this order on the said contact layer. Surface emitting laser array element.   6. The surface emitting laser array element according to claim 5, wherein the first metal film, the insulating film, and the second metal film have an opening for exposing a part of the contact layer.   The surface emitting laser array element according to claim 6, wherein an opening of the second metal film is larger than an opening of the insulating film.   6. The surface emitting laser array element according to claim 5, wherein the insulating film is formed so as to cover the contact layer. A surface-emitting laser array element according to any one of claims 1 to 8,
A microlens array in which light emitted from the surface emitting laser array element is parallel light;
A light source unit comprising: The light source unit according to claim 9;
A condensing lens that condenses the light emitted from the light source unit;
An optical fiber that transmits light collected by the condenser lens;
A laser device comprising:

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