JP2019140144A - Quantum cascade laser and light-emitting device - Google Patents

Abstract

To provide a structure for a quantum cascade laser arranged to use a metal film for a rear end face, which can reduce the risk of reducing the short circuit between a laser structure, a first electrode and a second electrode and a metal film.SOLUTION: A light-emitting device comprises: a sub-mount having a device-mount face and an end face having an upper edge arranged so as to be isolated from a front edge of the device-mount face; and a quantum cascade laser provided on the sub-mount. The quantum cascade laser includes a reflection structure provided on a laser structure. The reflection structure includes an insulation film and a metal film. The metal film has a first edge on a first face in a first region of the laser structure and a second edge on a second face in the first region. The insulation film has a first edge on the first face in the first region, and a second edge on the second face in the first region. The insulation film is located between the first and second edges of the metal film and the laser structure. The device-mount face of the sub-mount supports the second region of the laser structure of the quantum cascade laser.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a quantum cascade laser and a light emitting device including the quantum cascade laser.

  Non-Patent Document 1 discloses a quantum cascade laser.

Applied. Physics Letters, vol.89, 251119, 2006

  The reflection structure using the metal film on the rear end face can provide the quantum cascade laser with a low threshold current and heat dissipation from the rear end face. However, the waveguide mesa of the quantum cascade laser has reached the rear end face, and the metal film in contact with the rear end face causes an electrical short circuit in the core layer and the cladding layer above and below the core layer. In order to avoid contact of the metal film with the rear end face, an insulating film can be provided between the rear end face and the metal film.

  The quantum cascade laser includes a waveguide mesa in the laser structure, and supplies carriers to the waveguide mesa in the laser structure using the first electrode and the second electrode provided with the laser structure therebetween.

  A structure in which an insulating film and a metal film are sequentially arranged on the rear end face may be short-circuited by applying electricity to the quantum cascade laser. According to the inventor's observation, insulator and metal deposits are formed on the first electrode and the second electrode on the laser structure, and incidentally, the deposit is first on the laser structure. The electrode and the second electrode are short-circuited.

  One aspect of the present invention is to provide a quantum cascade laser that uses a metal film on the rear end face, and a structure that can reduce the possibility of a short circuit between the laser structure, the first electrode and the second electrode, and the metal film. It is another object of the present invention to provide a light emitting device including a submount and a quantum cascade laser mounted on the submount.

  A light-emitting device according to one aspect of the present invention includes a mounting surface on which a conductive layer is mounted, a submount having an upper surface spaced from a front edge of the mounting surface, and the mounting surface of the submount. And a quantum cascade laser provided on the leading edge, the quantum cascade laser including a waveguide mesa extending in a first axis direction and a substrate on which the waveguide mesa is mounted, and the waveguide A first end surface for terminating a mesa, a laser structure having a first surface and a second surface arranged in a direction of a second axis intersecting the direction of the first axis, and the first surface of the laser structure A first electrode provided on the second electrode; a second electrode provided on the second surface of the laser structure; and a reflective structure provided on the laser structure; Are first regions arranged in the direction of the first axis, An area, and a third area, the first area includes the first end face, the third area is provided between the first area and the second area, and the mounting of the submount A surface supports the second region of the laser structure of the quantum cascade laser, the reflective structure includes an insulating film and a metal film, and the metal film is on the first surface in the first region. A first edge of the metal film, and a second edge on the second surface in the first region, and the metal film is formed on the first electrode, the second electrode, and the first end face of the metal film. The insulating film extends from the first edge to the second edge of the metal film, and the insulating film has a first edge on the first surface in the first region and on the second surface in the first region. A second edge and in contact with the first end face from the first edge of the insulating film to the front of the insulating film. It extends to the second edge, wherein the insulating film is located between the first edge and the second edge of the metal film and the laser structure.

  A quantum cascade laser according to another aspect of the present invention includes a waveguide mesa extending in a direction of a first axis, a substrate on which the waveguide mesa is mounted, a first end surface that terminates the waveguide mesa, and the A laser structure having a first surface and a second surface arranged in a direction of a second axis intersecting the direction of the first axis, and a first electrode provided on the first surface of the laser structure; A second electrode provided on the second surface of the laser structure; and a reflective structure provided on the laser structure, wherein the laser structure is arranged in the direction of the first axis. A first region, a second region, and a third region, wherein the first region includes the first end face, and the third region is provided between the first region and the second region. The reflective structure includes an insulating film and a metal film, and the metal film is in the first region. A first edge on the first surface and a second edge on the second surface in the first region, wherein the metal film is on the first electrode, the second electrode, and the first end surface; Extending over the insulating film from the first edge of the metal film to the second edge of the metal film, the insulating film comprising: a first edge on the first surface in the first region; A second edge on the second surface in the first region and located between the first edge and the second edge of the metal film and the laser structure, and the insulating film is formed on the first end face. And extending from the first edge of the insulating film to the second edge of the insulating film.

  The above and other objects, features, and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings.

  As described above, according to some aspects of the present invention, a quantum cascade laser using a metal film on the rear end face may cause a short circuit between the laser structure, the first electrode and the second electrode, and the metal film. In addition, a light emitting device including a submount and a quantum cascade laser mounted on the submount can be provided.

FIG. 1 is a drawing schematically showing a light emitting device according to this embodiment. FIG. 2 is a partially broken view schematically showing a reflection end portion of the quantum cascade laser of the light emitting device according to the present embodiment. FIG. 3 is a cross-sectional view taken along lines IIIa-IIIa and IIIb-IIIb shown in FIG. FIG. 4 is a partially cutaway view schematically showing the emission end of the quantum cascade laser of the light emitting device according to this embodiment. FIG. 5 is a drawing schematically showing main steps in the method for producing the quantum cascade laser according to the present embodiment. FIG. 6 is a drawing schematically showing main steps in the method for producing the quantum cascade laser according to the present embodiment. FIG. 7 is a drawing schematically showing main steps in the method for producing the quantum cascade laser according to the present embodiment. FIG. 8 is a drawing schematically showing main steps in the method for producing the quantum cascade laser according to the present embodiment. FIG. 9 is a cross-sectional view schematically illustrating the light emitting device according to the first embodiment. FIG. 10 is a plan view schematically illustrating the light emitting device and the quantum cascade laser according to the first embodiment. FIG. 11 is a cross-sectional view schematically illustrating the light emitting device and the quantum cascade laser according to the second embodiment. FIG. 12 is a plan view schematically illustrating the light emitting device and the quantum cascade laser according to the second embodiment. FIG. 13 is a cross-sectional view schematically illustrating the light emitting device and the quantum cascade laser according to the third embodiment. FIG. 14 is a plan view schematically illustrating the light emitting device and the quantum cascade laser according to the third embodiment. FIG. 15 is a cross-sectional view schematically illustrating the light emitting device and the quantum cascade laser according to the fourth embodiment. FIG. 16 is a plan view schematically illustrating the light emitting device and the quantum cascade laser according to the fourth embodiment. FIG. 17 is a cross-sectional view schematically illustrating a light emitting device and a quantum cascade laser according to Example 5. FIG. 18 is a plan view schematically illustrating the light emitting device and the quantum cascade laser according to the fifth embodiment. FIG. 19 is a cross-sectional view schematically showing a light emitting device and a quantum cascade laser according to Example 6. FIG. 20 is a cross-sectional view schematically illustrating the light emitting device and the quantum cascade laser according to the seventh embodiment.

  Some specific examples are described.

  A light emitting device according to a specific example includes: (a) a submount having a mounting surface on which a conductive layer is mounted; and an end surface having an upper edge spaced from the front edge of the mounting surface; A quantum cascade laser provided on the mounting surface and the front edge, the quantum cascade laser including a waveguide mesa extending in a first axis direction and a substrate on which the waveguide mesa is mounted; A laser structure having a first end surface for terminating the waveguide mesa, and a first surface and a second surface arranged in a direction of a second axis intersecting the direction of the first axis; and the laser structure of the laser structure A first electrode provided on the first surface, a second electrode provided on the second surface of the laser structure, and a reflective structure provided on the laser structure, The laser structure is a first region arranged in the direction of the first axis. A second region and a third region; the first region includes the first end surface; the third region is provided between the first region and the second region; and The mounting surface supports the second region of the laser structure of the quantum cascade laser, the reflective structure includes an insulating film and a metal film, and the metal film includes the first region in the first region. A first edge on the surface and a second edge on the second surface in the first region, and the metal film is formed on the first electrode, the second electrode, and the first end surface. The insulating film extends from the first edge of the film to the second edge of the metal film, and the insulating film includes a first edge on the first surface in the first region and the second surface in the first region. And an insulating film from the first edge of the insulating film in contact with the first end face. It extends to the second edge, wherein the insulating film is located between the first edge and the second edge of the metal film and the laser structure.

  According to the light emitting device, the submount has a mounting surface spaced from the upper edge of the end surface, and the mounting surface supports the second region of the laser structure and does not support the third region. As a result, the metal film of the reflective structure of the quantum cascade laser can be separated from the conductive layer on the mounting surface.

  The quantum cascade laser has a reflective structure for the resonator on the laser structure. The reflective structure includes a metal film and an insulating film, and the metal film and the insulating film are also provided on the first surface and the second surface of the first region.

  Specifically, the metal film of the reflective structure has a structure including a main portion on the first end surface, and a first portion and a second portion located on the first surface and the second surface of the first region, respectively. By forming the first portion and the second portion that are continuously connected to the main portion, a desired thickness can be provided to the main portion of the metal film.

  The insulating film is located between the first edge and the second edge of the metal film and the laser structure and is in contact with the first end face. The insulating film includes a main portion that contacts the first end surface on the first end surface, and a first portion and a second portion that are connected to the main portion and located on the first surface and the second surface of the first region, respectively. It has a structure including. By forming the first part and the second part continuously connected to the main part, a desired thickness is provided to the first part and the second part in addition to the main part, and the metal film does not contact the first end face. You can

  Furthermore, the insulating film is provided between the first edge and the second edge of the metal film and the laser structure on the first surface and the second surface, and the metal film is provided with the first edge and the second edge of the insulating film. Thus, the metal film of the reflecting structure can be reliably separated from the first electrode and the second electrode of the quantum cascade laser.

  A quantum cascade laser according to a specific example includes (a) a first end face that includes a waveguide mesa extending in a first axis direction and a substrate on which the waveguide mesa is mounted, and terminates the waveguide mesa; A laser structure having a first surface and a second surface arranged in a direction of a second axis intersecting the direction of the first axis; and (b) a first electrode provided on the first surface of the laser structure. And (c) a second electrode provided on the second surface of the laser structure, and (d) a reflective structure provided on the laser structure, the laser structure comprising: The first region includes the first region, the second region, and the third region, the first region includes the first end surface, and the third region includes the first region and the second region. The reflective structure includes an insulating film and a metal film, and the metal film is formed in the first region. A first edge on the first surface and a second edge on the second surface in the first region, wherein the metal film comprises the first electrode, the second electrode, and the first end surface. Extending over the insulating film from the first edge of the metal film to the second edge of the metal film, the insulating film having a first edge on the first surface in the first region; A second edge on the second surface in the first region and located between the first edge and the second edge of the metal film and the laser structure, the insulating film being the first edge Continuing from the first edge of the insulating film to the second edge of the insulating film in contact with the end face.

  According to the quantum cascade laser, a reflecting structure for the resonator is provided on the laser structure. The reflective structure includes a metal film and an insulating film, and the metal film and the insulating film are also provided on the first surface and the second surface of the first region.

  Specifically, the metal film of the reflective structure has a structure including a main portion on the first end surface, and a first portion and a second portion located on the first surface and the second surface of the first region, respectively. By forming the first portion and the second portion that are continuously connected to the main portion, a desired thickness can be provided to the main portion of the metal film.

  The insulating film is located between the first edge and the second edge of the metal film and the laser structure and is in contact with the first end face. The insulating film includes a main portion that contacts the first end surface on the first end surface, and a first portion and a second portion that are connected to the main portion and located on the first surface and the second surface of the first region, respectively. It has a structure including. By forming the first part and the second part continuously connected to the main part, a desired thickness is provided to the first part and the second part in addition to the main part, and the metal film does not contact the first end face. You can

  Furthermore, the insulating film is provided between the first edge and the second edge of the metal film and the laser structure on the first surface and the second surface, and the metal film is provided with the first edge and the second edge of the insulating film. Thus, the metal film of the reflecting structure can be separated from the first electrode and the second electrode of the quantum cascade laser.

  In the light emitting device according to the specific example, the end surface of the submount extends along a reference plane intersecting the direction of the first axis, and the quantum cascade laser protrudes beyond the reference plane. Absent.

  According to the light emitting device, the quantum cascade laser is retracted with respect to the reference plane to reduce the possibility of unintentional damage.

  In the light emitting device according to the specific example, the laser structure includes a second end surface opposite to the first end surface, and the submount includes a protrusion protruding from the mounting surface, and the protrusion of the submount Positions the second end face of the quantum cascade laser.

  According to the light emitting device, positioning the second end face of the quantum cascade laser allows the position of the second end face to be accurately determined with respect to the submount.

  In the light emitting device according to the specific example, the second electrode is in contact with the substrate and has an edge separated from the lower end of the first end face.

  According to the light emitting device, the second electrode may not extend to the first end surface.

  In the light emitting device according to the specific example, the submount includes a step located at the edge of the mounting surface, and a recessed surface extending in the direction of the first axis from the upper edge of the end surface to the lower end of the step. The step has a side end surface extending from the mounting surface to the recessed surface, and the recessed surface is separated from the reflecting structure of the quantum cascade laser.

  According to the light emitting device, the concave surface of the submount extends in the direction of the first axis from the side end surface of the step located at the edge of the mounting surface to the upper edge of the end surface. The reflecting structure of the cascade laser can be separated.

  In the light emitting device according to the specific example, the conductive layer of the submount is provided on the side end face of the step.

  According to the light emitting device, by providing the conductive layer on the side end surface of the step, it is possible to reliably avoid the solder material on the mounting surface from reaching the reflective structure.

  In the light emitting device according to the specific example, the submount has one or a plurality of grooves extending in the direction of the third axis intersecting the first axis and the second axis and terminating the mounting surface. The submount includes a first region, a second region, and a third region arranged in the direction of the first axis, the first region includes the end surface, and the second region includes A mounting surface, the third region includes the groove, and the third region is provided between the first region and the second region, and the first region and the second region of the submount. Supports the quantum cascade laser.

  According to the light emitting device, the submount groove allows the first and second regions of the submount to support the quantum cascade laser, and the third region of the submount does not support the quantum cascade laser. .

  The light emitting device according to the specific example further includes a solder material that fixes the second electrode of the quantum cascade laser to the conductive layer.

  According to the light emitting device, the solder material on the conductive layer is separated from the reflective structure.

  In the light emitting device according to the specific example, the solder material includes any of AuSn, Sn, SnPb, AgSn, In, and silver paste.

  According to the light emitting device, the above solder material can be used.

  In the light emitting device according to the specific example, the submount includes any one of AlN, CuW, CuMo, and diamond.

  According to the light emitting device, the above-described submount material can be used.

  The light emitting device according to the specific example further includes a carrier on which the submount is mounted and die-bonded to the submount.

  According to the light emitting device, the submount may be die-bonded to the carrier.

  In the light emitting device according to the specific example, the carrier includes any one of Cu, CuW, Fe alloy, and brass.

  According to the light emitting device, the carrier material described above can be used.

In the light emitting device and the quantum cascade laser according to the specific example, the insulating film includes any of SiO ₂ , SiON, SiN, alumina, BCB, and polyimide.

  According to the light emitting device and the quantum cascade laser, the above insulating film can be used.

  In the light emitting device and the quantum cascade laser according to the specific example, the metal film includes gold.

  According to the light emitting device and the quantum cascade laser, gold can be used for the metal film.

  The knowledge of the present invention can be easily understood by considering the following detailed description with reference to the accompanying drawings shown as examples. Subsequently, embodiments of the light emitting device, the quantum cascade laser, and the method for manufacturing the light emitting device and the quantum cascade laser will be described with reference to the accompanying drawings. Where possible, the same parts are denoted by the same reference numerals.

  FIG. 1 is a drawing schematically showing a light emitting device according to this embodiment. FIG. 2 is a partially broken view schematically showing a reflection end portion of the quantum cascade laser of the light emitting device according to the present embodiment. Part (a) of FIG. 3 is a cross-sectional view taken along line IIIa-IIIa shown in FIG. Part (b) of FIG. 3 is a cross-sectional view taken along line IIIb-IIIb shown in FIG. Parts (a) and (b) of FIG. 4 are partially broken views schematically showing the emission end of the quantum cascade laser of the light emitting device according to this embodiment.

  Referring to FIG. 1, the light emitting device 11 includes a quantum cascade laser 13 and a submount 15. The quantum cascade laser 13 is provided on the submount 15.

  1 to 4, the quantum cascade laser 13 includes a laser structure 17, a first electrode 19, a second electrode 21, and a reflective structure 23. The laser structure 17 includes a waveguide mesa 25 extending in the direction of the first axis Ax1, a substrate 27 on which the waveguide mesa 25 is mounted, a first end surface 29, and a second end surface 31. The first end surface 29 and the second end surface 31 are arranged in the direction of the first axis Ax1. The waveguide mesa 25 terminates at the first end face 29, and the waveguide mesa 25 extends from the second end face 31 to the first end face 29 in this embodiment. The laser structure 17 has a first surface 17a and a second surface 17b, and the first surface 17a and the second surface 17b are arranged in the direction of the second axis Ax2 that intersects the direction of the first axis Ax1. And extends in the direction of the first axis Ax1. The first electrode 19 and the second electrode 21 are provided on the first surface 17a and the second surface 17b of the laser structure 17, respectively. Specifically, the first surface 17a and the second surface of the laser structure 17 are provided. Contact is made to 17b. The laser structure 17 includes a first region 17c, a second region 17d, and a third region 17e, and the first region 17c, the second region 17d, and the third region 17e are arranged in the first axis Ax1 direction. . The third region 17e is provided between the first region 17c and the second region 17d. The first region 17 c can include the first end surface 29, and the second region 17 d can include the second end surface 31.

  The reflection structure 23 is provided on the laser structure 17. Specifically, the reflecting structure 23 is provided on the first end surface 29 and is not provided on the second end surface 31. The reflective structure 23 includes a metal film 33 and an insulating film 35.

  The metal film 33 has a first edge 33a located on the first surface 17a in the first region 17c and a second edge 33b located on the second surface 17b in the first region 17c. The metal film 33 extends on the first electrode 19, the second electrode 21, and the first end surface 29 from the first edge 33 a of the metal film 33 to the second edge 33 b of the metal film 33.

  The insulating film 35 has a first edge 35a located on the first surface 17a in the first region 17c and a second edge 35b located on the second surface 17b in the first region 17c, and the first end face 29. To the second edge 35b of the insulating film 35 from the first edge 35a of the insulating film 35. The insulating film 35 is located between the first edge 33 a and the second edge 33 b of the metal film 33 and the laser structure 17.

  According to the quantum cascade laser 13, the reflecting structure 23 for the resonator is provided on the laser structure 17. The reflective structure 23 includes a metal film 33 and an insulating film 35, and the insulating film 35 is located between the first edge 33 a and the second edge 33 b of the metal film 33 and the laser structure 17 and contacts the first end face 29. Is made. The metal film 33 of the reflective structure 23 includes a main portion 33c provided on the first end surface 29, and a first portion 33d and a second portion located on the first surface 17a and the second surface 17b of the first region 17c, respectively. 33e and the first portion 33d and the second portion 33e connected to the main portion 33c can provide a desired thickness to the main portion 33c of the metal film 33.

  The insulating film 35 includes a main portion 35c that is in contact with the first end surface 29, and a first portion 35d that is connected to the main portion 35c and provided on the first surface 17a and the second surface 17b of the first region 17c, respectively. Second portion 35e. By forming the first portion 35d and the second portion 35e connected to the main portion 35c, it is possible to provide the main portion 35c with a desired thickness and to ensure that the metal film 33 does not contact the first end face 29. The insulating film 35 is provided on the first surface 17 a and the second surface 17 b between the first edge 33 a and the second edge 35 b of the metal film 33 and the laser structure 17, and the metal film 33 is formed of the insulating film 35. It is possible to avoid covering the first edge 35 a and the second edge 35 b, thereby separating the metal film 33 of the reflective structure 23 from the first electrode 19 and the second electrode 21 of the quantum cascade laser 13.

  Referring back to FIG. 1, the submount 15 includes a base 15a and a conductive layer 15b on the base 15a. The base 15a has a mounting surface 15c on which the conductive layer 15b is mounted and an end surface 15d. It has an upper edge 15f spaced from the front edge 15e of the surface 15c. The front edge 15e of the mounting surface 15c and the upper edge 15f of the end surface 15d are arranged in the direction of the first axis Ax1.

  The mounting surface 15 c of the submount 15 supports the second region 17 d of the laser structure 17 of the quantum cascade laser 13, but does not support the third region 17 e of the laser structure 17 of the quantum cascade laser 13.

  According to the light emitting device 11, the submount 15 has the mounting surface 15 c spaced from the upper edge 15 f of the end surface 15 d, and the mounting surface 15 c supports the second region 17 d of the laser structure 17. The third region 17e is not supported. As a result, the metal film 33 of the reflecting structure 23 of the quantum cascade laser 13 can be separated from the conductive layer 15b on the mounting surface 15c.

  The quantum cascade laser 13 has a reflecting structure 23 for the resonator on the laser structure 17. The reflective structure 23 includes a metal film 33 and an insulating film 35. The metal film 33 and the insulating film 35 are also provided on the first surface 17a and the second surface 17b of the first region 17c.

  Specifically, the metal film 33 of the reflective structure 23 includes a main portion 33c located on the first end surface 29 and a first portion located on each of the first surface 17a and the second surface 17b of the first region 17c. By forming the first portion 33d and the second portion 33e that have a structure including the third portion 33d and the second portion 33e and are continuously connected to the main portion 33c, a desired thickness can be provided to the main portion 33c of the metal film 33. . The insulating film 35 is located between the first edge 33 a and the second edge 33 b of the metal film 33 and the laser structure 17 and is in contact with the first end face 29. The insulating film 35 is in contact with the main portion 35c that is in contact with the first end surface 29 on the first end surface 29, and the first portion 17a and the second surface 17b of the first region 17c that are connected to the main portion 35c. And a first portion 35d and a second portion 35e. By forming the first portion 35d and the second portion 35e continuously connected to the main portion 35c, a desired thickness is provided to the first portion 35d and the second portion 35e in addition to the main portion 35c, and reliably. The metal film 33 can be prevented from contacting the first end surface 29.

  Further, the insulating film 35 is provided between the first edge 33a and the second edge 33b of the metal film 33 and the laser structure 17 on the first surface 17a and the second surface 17b. 35, it is possible to avoid reaching or covering the first edge 35 a and the second edge 35 b, thereby ensuring that the metal film 33 of the reflecting structure 23 is formed on the first electrode 19 and the first electrode of the quantum cascade laser 13. It can be separated from the two electrodes 21.

The insulating film 35 can include at least one of SiO ₂ , SiON, SiN, alumina, benzocyclobutene (BCB), and polyimide. According to the light emitting device 11, the above insulating material can be used for the insulating film 35. These insulators can provide excellent durability and insulation. These dielectric films can be easily formed using a film forming method such as sputtering, CVD, or spin coating.

  The metal film 33 can include gold. According to the light emitting device 11, gold can be used for the metal film 33. The gold film can be formed, for example, by vapor deposition.

  The light emitting device 11 can further include a solder material 37 that fixes the second electrode 21 of the quantum cascade laser 13 to the conductive layer 15 b of the submount 15. According to the light emitting device 11, the solder material 37 on the conductive layer 15 b is separated from the reflective structure 23.

  The base 15a of the submount 15 can include at least one of AlN, CuW, CuMo, and diamond. According to the light emitting device 11, the submount 15 can use the above-described submount material. If necessary, the submount 15 can be provided with an insulating film that provides insulation to the mounting surface 15c on the conductive base 15a. The solder material 37 may include at least one of AuSn, Sn, SnPb, AgSn, In, and silver paste. According to the light emitting device 11, the above solder material can be used.

  The light emitting device 11 can further include a carrier 39 on which the submount 15 is mounted. The submount 15 may be die-bonded to the carrier 39. The carrier 39 can include any of Cu, CuW, Fe alloy, and brass. According to the light emitting device 11, the above carrier material can be used.

  2 and 3, in the quantum cascade laser 13, the waveguide mesa 25 includes a core layer 25a, a lower cladding layer 25b, and an upper cladding layer 25c, and may further include a contact layer 25d. The quantum cascade laser 13 can have a Fabry-Perot type. Alternatively, the quantum cascade laser 13 may have a distributed feedback type, and further includes a diffraction grating layer 25e. The diffraction grating layer 25 e has a periodic structure that defines the oscillation wavelength of the quantum cascade laser 13. In this embodiment, the waveguide mesa 25 includes a lower clad layer 25b, a core layer 25a, a diffraction grating layer 25e, an upper clad layer 25c, and a contact layer 25d, and is arranged in order on the main surface 27a of the substrate 27. The quantum cascade laser 13 can include a semiconductor embedded region 26 that embeds the side surface of the waveguide mesa 25 and functions as a current blocking layer. The semiconductor embedded region 26 is a high-resistivity undoped semiconductor and / or semi-insulating. A functional semiconductor. The first electrode 19 is provided on the semiconductor buried region 26 and the waveguide mesa 25, and the second electrode 21 is provided on the back surface 27 b of the substrate 27. The substrate 27 can include, for example, a conductive semiconductor substrate.

  In the present embodiment, the light emitting device 11 can include an end face film 38 that functions as a protective film or an end face reflectivity control film provided on the second end face 31, and the laser light beam L passes through the end face film 38. Can be emitted. Alternatively, the light emitting device 11 can emit the laser light beam L directly from the second end face 31 without providing the end face film 38.

  In the quantum cascade laser 13, as shown in FIG. 4A, the metal film 33 of the reflecting structure 23 has a thickness T33U at the position of the first edge 33a, and the thickness T33U is, for example, 10 nm or more. The insulating film 35 of the reflective structure 23 has a thickness T35U at the position of the first edge 35a, and the thickness T35U is, for example, 20 nm or more. Further, the upper interval EXTU between the first edge 33a of the metal film 33 and the first edge 35a of the insulating film 35 is, for example, 10 to 100 nm.

  4B, the metal film 33 of the reflective structure 23 has a thickness T33D at the position of the second edge 33b, and the thickness T33D is, for example, 10 nm or more. The insulating film 35 of the reflective structure 23 has a thickness T35D at the position of the second edge 35b, and the thickness T35D is, for example, 20 nm or more. Further, the upper interval EXTD between the second edge 33b of the metal film 33 and the second edge 35b of the insulating film 35 is, for example, 10 to 100 nm.

  The metal film 33 of the reflective structure 23 has a thickness T33F on the first end face 29, and the thickness T33F is, for example, 50 to 200 nm. The sufficiently large thicknesses T33U and T33D can provide the desired thickness T33F on the first end face 29. Further, the insulating film 35 of the reflective structure 23 has a thickness T35F on the first end face 29, and the thickness T35F is, for example, 100 to 300 nm. The sufficiently large thicknesses T35U and T35D can provide a desired thickness T35F on the first end face 29.

  A method for producing the quantum cascade laser 13 will be described with reference to FIGS. For ease of understanding, the manufacturing method will be described using the reference numerals used for the quantum cascade laser 13 when possible.

  As shown in part (a) of FIG. 5, a substrate product SP is prepared. In this embodiment, the substrate product SP includes a support (substrate 27), a plurality of waveguide mesas 25 extending on the support, a semiconductor buried region 26 in which the waveguide mesas 25 are embedded, and an upper electrode layer. It includes a continuous film of (first electrode 19) and a continuous film of the lower electrode layer (second electrode 21). The substrate product SP includes an element array capable of producing four laser bars LDB. The substrate product SP is manufactured using a semiconductor process such as crystal growth, photolithography, etching, and regrowth, and is manufactured from a wafer product.

  As shown in part (b) of FIG. 5, the substrate product SP is divided by cleavage to obtain a laser bar LDB1. The laser bar LDB1 has a one-dimensional array including 12 element sections.

  As shown in part (a) of FIG. 6, deposition for the insulating film 35 is performed on the first end face 29. In order to obtain the desired first edge 35a and second edge 35b, the upper protector PTU and the lower protector PTD are used. The upper protector PTU and the lower protector PTD respectively define the first region of the laser structure 17 of the laser bar LDB1. The upper protector PTU and the lower protector PTD are aligned so as not to cover, and the first electrode 19 and the second electrode 21 are covered. The upper protector PTU and the lower protector PTD do not cover the first electrode 19 and the second electrode 21 and the first end face 29 on the first region 17c of the laser structure 17 of the laser bar LDB1. After the upper protector PTU and the lower protector PTD are attached to the laser bar LDB1, the flux F35 for the insulating film 35 is provided toward the first end face 29 of the laser structure 17 to complete the deposition of the insulating film 35. The insulating film 35 is formed on the first electrode 19, the second electrode 21, and the first end surface 29 in the first region 17 c.

  As shown in FIG. 6B, the upper protector PTU and the lower protector PTD are removed from the laser bar LDB1, and the laser bar LDB1 including the insulating film 35 having the first edge 35a and the second edge 35b at a desired position. obtain.

  As shown in FIG. 7A, the metal film 33 is deposited on the first end face 29. In order to obtain the desired first edge 33a and second edge 33b, the upper protector PTU and the lower protector PTD are used. The upper protector PTU and the lower protector PTD are respectively the first edge 35a of the insulating film 35 on the laser bar LDB1. The upper protector PTU and the lower protector PTD are aligned so as to cover a desired partial area of the first part 35d and the second part 35e including the second edge 35b, and the first electrode 19 and the second electrode 21 and the end portion of the insulating film 35 are covered to prevent the metal from being deposited near the end portion of the insulating film 35. The upper protector PTU and the lower protector PTD include a part of a desired portion including the first edge 35a and the second edge 35b on the first electrode 19 and the second electrode 21 on the first region of the laser structure 17 of the laser bar LDB1. The insulating film 35 other than the area and the insulating film 35 on the first end face 29 are not covered.

  As shown in FIG. 7B, after the upper protector PTU and the lower protector PTD are attached again to the laser bar LDB1, the flux F33 for the metal film 33 is applied toward the first end face 29 of the laser structure 17. Provide to complete the deposition of the metal film 33. A continuous film of the metal film 33 is formed on the first surface 17a and the second surface 17b and the first end surface 29 of the first region 17c.

  As shown in FIG. 8A, the upper protector PTU and the lower protector PTD are removed from the laser bar LDB1, and the metal film 33 having the first edge 33a and the second edge 33b at a desired position on the insulating film 35. A laser bar LDB1 containing is obtained.

  If necessary, deposition for the end face film 38 is performed on the second end face 31 as shown in part (b) of FIG. After the upper protector PTU and the lower protector PTD are attached to the laser bar LDB1, the flux F38 is provided toward the second end face 31 of the laser structure 17 to complete the deposition. Thereafter, the upper protector PTU and the lower protector PTD are removed from the laser bar LDB1, and the laser bar LDB1 including the insulating film 35 and the metal film 33 is obtained. The laser bar LDB1 is divided at the boundary of the element section to obtain the quantum cascade laser 13 including the reflecting structure 23.

Example 1
The quantum cascade laser 13 according to the first embodiment will be described with reference to FIGS. 9 and 10. 9 is a cross-sectional view taken along line IX-IX in FIG. The substrate 27 has conductivity, and can include, for example, an n-type InP substrate. The semiconductor material of the semiconductor layer of the quantum cascade laser that emits mid-infrared laser light has a lattice constant close to InP. InP semiconductor substrates can provide good crystal quality for these semiconductor layers. InP can transmit mid-infrared light, and this InP substrate can be used as a lower cladding. A semiconductor substrate is used for crystal growth by growth methods such as molecular beam epitaxy and metal organic chemical vapor deposition.

  The lower cladding layer 25b and the upper cladding layer 25c can include n-InP that can transmit mid-infrared light. InP in the lower cladding layer 25b and the upper cladding layer 25c is lattice-matched to the InP substrate. InP is a binary mixed crystal and can provide good crystal growth on the InP substrate. Furthermore, the thermal conductivity of InP is the largest among the semiconductor materials that can be used in the mid-infrared quantum cascade laser, and the InP clad layer enables good heat dissipation from the core layer 25a, thereby enabling quantum cascade. The skate laser can be provided with improved temperature characteristics.

  The core layer 25a uses a stacked unit structure including an active layer and an injection layer, and specifically includes active layers and injection layers that are alternately connected in multiple stages. Each of the active layer and the injection layer includes a superlattice structure, and the superlattice structure includes a plurality of quantum well layers and a plurality of barrier layers stacked alternately. Each quantum well layer is a thin film having a thickness of several nanometers, and each barrier layer is a thin film having a higher band gap and several nanometers than the quantum well layer. Quantum cascade lasers use single carriers, for example electrons, to resonate mid-infrared light emitted by intersubband transitions from upper to lower subband levels in the conduction band in the active layer Amplify with a vessel. Intersubband transitions can provide light at mid-infrared wavelengths. As described above, the core layer 25a is composed of the superlattice structure active layer and the injection layer superlattice structure which are alternately arranged, and the sublayer in the conduction band of the upstream active layer passes through the injection layer. Electrons that cause light emission due to interband transition are smoothly injected into the downstream active layer, and light emission due to intersubband transition in each active layer occurs continuously, and as a result, oscillation as QCL becomes possible. The quantum well layer can comprise, for example, GaInAs and GaInAsP, and the barrier layer can comprise AlInAs. The superlattice structure of the active layer including these materials including a quantum well layer and a barrier layer can provide an energy difference between an upper level and a lower level that provide a transition of a mid-infrared wavelength of, for example, 3 to 20 μm.

  The contact layer 25d is used when necessary. The contact layer 25d has a low band gap that can provide a good ohmic contact to the first electrode 19, and includes a material that can be lattice-matched to the InP substrate, and can include, for example, n-GaInAs.

  The diffraction grating layer 25 e provides a distributed feedback structure for the quantum cascade laser 13. The diffraction grating layer 25e has a diffraction grating structure formed by etching so as to extend in the direction of the first axis Ax1. The diffraction grating structure can provide a single mode oscillation with a Bragg wavelength corresponding to the period P. The diffraction grating layer 25e may include a high refractive index semiconductor capable of providing a large coupling coefficient, such as undoped or n-type GaInAs.

The semiconductor buried region 26 provides a buried heterostructure for the quantum cascade laser 13. The semiconductor buried region 26 functions as a current blocking layer including a high-resistance undoped or semi-insulating semiconductor, and traps carriers in the waveguide mesa 25. The semi-insulating semiconductor is a III-V compound semiconductor to which a transition metal such as Fe, Ti, Cr, or Co is added, and particularly preferably includes a Fe dopant. According to the addition of the transition metal, the semi-insulating semiconductor can provide a high resistance of, for example, 10 ⁵ (Ωcm) or more to electrons. If possible, an undoped III-V compound semiconductor may be used for the current blocking layer instead of the semi-insulating semiconductor. The undoped or semi-insulating semiconductor buried layer is provided by a compound semiconductor such as InP, GaInAs, AlInAs, GaInAsP, and AlGaInAs. These semiconductors lattice match with InP.

  The first electrode 19 and the second electrode 21 can comprise, for example, Ti / Au, Ti / Pt / Au, or Ge / Au.

  If necessary, an optical confinement region can be provided above, below or above and below the core layer 25a to enhance the confinement of guided light into the core layer 25a. The optical confinement region may comprise a high refractive index semiconductor that can be lattice matched to InP, such as undoped, n-type GaInAs.

  Giving n-type conductivity to a semiconductor is realized by adding an n-type dopant such as Si, S, Sn, or Se.

The quantum cascade laser 13 may have a high mesa structure including a dielectric insulating film that covers the side surface of the waveguide mesa 25 instead of the semiconductor buried region 26. The dielectric insulating film functions as a current confinement structure, and can include a silicon-based inorganic insulating film such as SiO ₂ , SiON, or SiN.

  A light emitting device according to Example 1 will be described with reference to FIGS. 9 and 10. The quantum cascade laser 13 aligns the rear end of the element including the reflecting structure 23 with the end face 15d (marker) of the submount 15 in the first axis Ax1 direction, so that the quantum cascade laser 13 is on the conductive layer 15b of the submount 15 as a reference. Aligned. The retraction amount SB of the front edge 15e with respect to the end face 15d can be, for example, 100 to 200 nm.

  In addition, in order to obtain the insulating film 35 and the metal film 33 having sufficient thickness on the first electrode 19 and the second electrode 21, the length of the first region 17c and the first length L1 are, for example, 100 nm or less. In order to obtain the insulating film 35 and the metal film 33 with sufficient covering amounts on the first electrode 19 and the second electrode 21, the first length L1 can be, for example, 20 nm or more.

  In the submount 15, the front edge 15e of the mounting surface 15c is recessed from the upper edge 15f of the end surface 15d by the retraction amount SB, and has a recess positioned between the end surface 15d and the front edge 15e. In this embodiment, the submount 15 includes a step STP located at the front edge 15e of the mounting surface 15c, and a recessed surface 15g extending in the direction of the first axis Ax1 from the upper edge 15f of the end surface 15d to the lower end of the step STP. Have The step STP has a side end surface 15h extending from the mounting surface 15c to the recessed surface 15g. The concave surface 15 g is separated from the reflecting structure 23 of the quantum cascade laser 13.

  According to the light emitting device 11, the concave surface 15g of the submount 15 extends in the direction of the first axis Ax1 from the side end surface 15h of the step STP located at the front edge 15e of the mounting surface 15c to the upper edge 15f of the end surface 15d. The reflecting structure 23 of the quantum cascade laser 13 can be separated from the conductive layer 15b of the submount 15. The distance between the edge of the solder material 37 that fixes the second electrode 21 and the second edge (the second edge 33b and the second edge 35b) of the reflecting structure 23 (the width of the third region 17e) provides reliable insulation. In order to provide an appropriate carrier path, a bonding force between the submount 15 and the quantum cascade laser 13, and / or a heat dissipation path for the submount, for example, 100 nm or less. Can be.

  In the submount 15, the step STP includes an inclined surface extending from the front edge 15e of the mounting surface 15c to the upper edge 15f of the end surface 15d, instead of the step STP defined by the recessed surface 15g and the side end surface 15h. it can.

(Example 2)
A light-emitting device according to Example 2 will be described with reference to FIGS. 11 is a cross-sectional view taken along line XI-XI in FIG. In the light emitting device 11 according to the second embodiment, the submount 15 includes a groove GV that extends in the direction of the third axis Ax3 intersecting the first axis Ax1 and the second axis Ax2 and terminates the mounting surface 15c. The groove GV is defined by a step STP that terminates the mounting surface 15c and a wall portion WLL extending in the direction of the third axis Ax3. Specifically, the side end surface 15h, the recessed surface 15g, and the wall side surface 15i. It is prescribed by. In the present embodiment, the wall part WLL includes an end face 15d.

  The submount 15 includes a first region R1, a second region R2, and a third region R3 arranged in the first axis Ax1 direction. The third region R3 is between the first region R1 and the second region R2. Provided. The first region R1 includes an end surface 15d, the second region includes a mounting surface 15c, and the third region R3 includes a groove GV. The first region R1 and the second region R2 of the submount 15 support the quantum cascade laser 13, and the third region R3 does not support the quantum cascade laser 13.

  According to the light emitting device 11, the groove GV of the submount 15 enables the first region R <b> 1 and the second region R <b> 2 of the submount 15 to support the quantum cascade laser 13. The support of the quantum cascade laser 13 in the first region R1 provides a heat dissipation path for heat generation in the core layer 25a near the first end face 29. Similarly, since the first region R1 supports the quantum cascade laser 13, the mechanical strength of the quantum cascade laser 13 in the vicinity of the first end face 29 is improved, and the resistance of the quantum cascade laser 13 to an impact such as vibration or dropping is also improved. It is done. The third region R3 of the submount includes the groove GV, and separates the solder material 37 on the conductive layer 15b without supporting the quantum cascade laser. Specifically, the solder material 37 on the first region R1 of the submount 15 is in contact with the metal film 33 while being insulated from the second electrode 21 by the insulating film 35. The conductive layer 15b on the second region R2 of the submount 15 is connected to the second electrode 21 via the solder material 37.

  The quantum cascade laser 13 aligns the rear end of the element including the reflective structure 23 with the end surface 15d (marker) of the submount 15 in the first axis Ax1 direction, so that the quantum cascade laser 13 is on the conductive layer 15b of the submount 15 as a reference. Aligned.

(Example 3)
A light emitting device according to Example 3 will be described with reference to FIGS. 13 and 14. 13 is a cross-sectional view taken along line XIII-XIII in FIG. In the light emitting device 11 according to Example 3, the submount 15 includes the groove GV extending in the direction of the third axis Ax3 and terminating the mounting surface 15c, and one or a plurality of intermediate walls MDW provided in the groove GV. Including. The intermediate wall MDW extends in the direction of the third axis Ax3 and does not support the quantum cascade laser 13. The conductive layer 15b of the submount 15 is not provided on the upper surface of the intermediate wall MDW. The intermediate wall MDW in the groove GV can prevent the solder material 37 on the second region R2 of the submount 15 from being accidentally connected to the solder material 37 on the first region R1. The heat generated in the quantum cascade laser 13 is transmitted to the submount 15 via the solder material 37 on the second region R2 of the submount 15 and the solder material 37 on the first region R1.

  The quantum cascade laser 13 is aligned on the conductive layer 15b of the submount 15 with respect to the end surface 15d (marker) of the submount 15 with respect to the end surface 15d (marker) of the submount 15 in the first axis Ax1 direction.

Example 4
A light emitting device according to Example 4 will be described with reference to FIGS. 15 and 16. The quantum cascade laser 13 according to the fourth embodiment can include a protrusion 41 located at the boundary between the second region 17d and the third region 17e. The protrusion 41 is provided on the first electrode 19 and can extend from one side of the quantum cascade laser 13 to the other side in the direction of the third axis Ax3. The quantum cascade laser 13 is positioned on the conductive layer 15b of the submount 15 by aligning the protrusion 41 with the front edge 15e (side end surface 15h) of the mounting surface 15c of the submount 15 in the first axis Ax1 direction. Can be aligned. As the protrusion 41, for example, a dielectric material such as SiO2, SiON, SiN, alumina, BCB, polyimide or the like can be used. Moreover, although the example which uses the protrusion 41 for the alignment marker on an element surface was shown as an example here, it is not limited to this, For example, as a recessed part pattern etc. which were formed by etching an upper electrode, as a marker Any available structure or material can be used. However, if necessary, the quantum cascade laser 13 is positioned on the conductive layer 15b of the submount 15 by aligning the rear end of the element including the reflective structure 23 with the end face 15d (marker) of the submount 15. You may make it match | combine.

  Further, the end face 15d of the submount 15 extends along the reference plane REF. The quantum cascade laser 13 does not protrude beyond the reference plane REF. According to the light emitting device 11, the quantum cascade laser 13 moves backward with respect to the reference plane REF, thereby reducing the possibility of unintentional damage. The retraction amount SB is independent of the length of the recessed surface 15g.

  The protrusion 41 according to the fourth embodiment can be used for the quantum cascade laser 13 according to the first to third embodiments and the subsequent embodiments.

(Example 5)
A light-emitting device according to Example 5 will be described with reference to FIGS. 17 is a cross-sectional view taken along line XVII-XVII in FIG. In the light emitting device 11 according to the fifth embodiment, the submount 15 includes a protrusion 15j protruding from the mounting surface 15c. The protrusion 15j has a height sufficiently lower than the height of the core layer of the quantum cascade laser 13, and is lower than the height of the main surface 27a of the substrate 27, for example. The protrusion 15j of the submount 15 positions the second end surface 31 opposite to the first end surface 29 of the quantum cascade laser 13 in the first axis Ax1 direction. According to the light emitting device 11, the positioning of the second end face 31 of the quantum cascade laser 13 makes it possible to accurately determine the position of the second end face 31 with respect to the submount 15. In this embodiment, the protrusion 15j is located at the other end 15k located on the opposite side of the end face 15d.

  The protrusion 15j according to the fifth embodiment can be used for the submount 15 according to the first to third embodiments and the rear embodiment.

(Example 6)
A light emitting device according to Example 6 will be described with reference to FIGS. 10 and 19. 19 is a cross-sectional view taken along line IX-IX in FIG. In the light emitting device 11 according to Example 6, the second electrode 21 of the quantum cascade laser 13 is in contact with the back surface 27 b of the substrate 27 and has an edge 21 a that is separated from the lower end 29 d of the first end surface 29. Specifically, the second electrode 21 is provided on the second surface 17b of the second region 17d of the laser structure 17, and is not provided on the second surface 17b of the first region 17c and the third region 17e. . According to the light emitting device 11, the second electrode 21 may not extend to the first end surface 29.

  The edge 21 a of the second electrode 21 is away from the reflecting structure 23, specifically, away from the second edge 35 b of the insulating film 35 and the second edge 33 b of the metal film 33 of the reflecting structure 23. The insulating film 35 of the reflecting structure 23 is in contact with the second surface 17b of the laser structure 17, and the insulating film 35 is formed from the second surface 17b of the laser structure 17 (the back surface 27b of the substrate 27). Can be insulated. The distance between the edge 21a of the second electrode 21 and the second edge (second edge 33b and second edge 35b) of the reflecting structure 23 can be, for example, 10 nm or more in order to obtain reliable insulation. In order to provide a simple carrier path, it can be, for example, 100 nm or less.

  The second electrode 21 according to the sixth embodiment can be used in the quantum cascade laser 13 according to the first to fifth embodiments and the subsequent embodiments.

(Example 7)
A light emitting device according to Example 7 will be described with reference to FIG. In the light emitting device 11 according to Example 7, the conductive layer 15b of the submount 15 extends from the mounting surface 15c to the side end surface 15h via the front edge 15e. The excess molten solder on the conductive layer 15b of the submount 15 flows along the conductive layer 15b on the side end face 15h. Since the surplus of the molten solder material 37 is absorbed by the conductive layer 15b on the side end face 15h, the solder material 37 that joins the quantum cascade laser 13 and the conductive layer 15b of the submount 15 to the reflective structure 23. You can avoid reaching.

  The second electrode 21 according to the seventh embodiment can be used for the quantum cascade laser 13 according to the first to sixth embodiments.

  The submount 15 and the quantum cascade laser 13 are not limited to the specific examples described above in the embodiment.

  In this embodiment, it is difficult for the solder material 37 on the submount 15 to come into contact with the metal film 33 for highly reflecting the end surface, and therefore a short circuit via the metal film 33 in the reflective structure 23 can be avoided.

  While the principles of the invention have been illustrated and described in the preferred embodiments, it will be appreciated by those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. The present invention is not limited to the specific configuration disclosed in the present embodiment. We therefore claim all modifications and changes that come within the scope and spirit of the following claims.

  As described above, according to the present embodiment, it is possible to reduce the possibility of a short circuit between the laser structure, the first electrode and the second electrode, and the metal film in the quantum cascade laser using the metal film on the rear end face. A structure can be provided, and a light-emitting device including a submount and a quantum cascade laser mounted on the submount can be provided.

DESCRIPTION OF SYMBOLS 11 ... Light-emitting device, 13 ... Quantum cascade laser, 15 ... Submount, 17 ... Laser structure, 19 ... 1st electrode, 21 ... 2nd electrode, 23 ... Reflective structure, 25 ... Waveguide mesa, 27 ... Substrate, 29 ... 1st end surface, 31 ... 2nd end surface, 33 ... Metal film, 35 ... Insulating film.

Claims (15)

A light emitting device,
A submount having a mounting surface on which the conductive layer is mounted, and an end surface having an upper edge spaced from the front edge of the mounting surface;
A quantum cascade laser provided on the mounting surface and the leading edge of the submount;
With
The quantum cascade laser is:
A first end face that terminates the waveguide mesa, and a second axis that intersects the first axis direction, the waveguide mesa extending in the first axis direction and a substrate on which the waveguide mesa is mounted. A laser structure having a first surface and a second surface arranged in a direction;
A first electrode provided on the first surface of the laser structure;
A second electrode provided on the second surface of the laser structure;
A reflective structure provided on the laser structure;
Including
The laser structure includes a first region, a second region, and a third region arranged in the direction of the first axis, the first region includes the first end surface, and the third region includes: Provided between the first region and the second region, the mounting surface of the submount supports the second region of the laser structure of the quantum cascade laser;
The reflective structure includes an insulating film and a metal film,
The metal film has a first edge on the first surface in the first region and a second edge on the second surface in the first region, and the metal film includes the first electrode, Extending on the second electrode and the first end surface from the first edge of the metal film to the second edge of the metal film;
The insulating film has a first edge on the first surface in the first region and a second edge on the second surface in the first region, and makes contact with the first end surface. The insulating film extends from the first edge of the insulating film to the second edge of the insulating film, and the insulating film is positioned between the first edge and the second edge of the metal film and the laser structure. A light emitting device. The end surface of the submount extends along a reference plane intersecting the first axis;
The light emitting device according to claim 1, wherein the quantum cascade laser does not protrude beyond the reference plane. The laser structure includes a second end surface opposite to the first end surface,
The submount has a protrusion protruding from the mounting surface,
The light emitting device according to claim 1, wherein the protrusion of the submount positions the second end face of the quantum cascade laser.   4. The light emitting device according to claim 1, wherein the second electrode is in contact with the substrate and has an edge separated from a lower end of the first end surface. The submount has a step located at the front edge of the mounting surface, and a concave surface extending in the direction of the first axis from the upper edge of the end surface to the lower end of the step,
The step has a side end surface extending from the mounting surface to the recessed surface,
The light emitting device according to any one of claims 1 to 4, wherein the concave surface is separated from the reflective structure of the quantum cascade laser.   The light emitting device according to claim 5, wherein the conductive layer of the submount is provided on the side end surface of the step. The submount has one or a plurality of grooves extending in the direction of a third axis intersecting the first axis and the second axis and terminating the mounting surface,
The submount includes a first region, a second region, and a third region arranged in the direction of the first axis, the first region includes the end surface, and the second region includes the mounting surface. The third region includes the groove, and the third region is provided between the first region and the second region,
5. The light-emitting device according to claim 1, wherein the first region and the second region of the submount support the quantum cascade laser.   The light emitting device according to any one of claims 1 to 7, further comprising a solder material that fixes the second electrode of the quantum cascade laser to the conductive layer.   The light emitting device according to claim 8, wherein the solder material includes any of AuSn, Sn, SnPb, AgSn, In, and silver paste.   The light emitting device according to any one of claims 1 to 9, wherein the submount includes any one of AlN, CuW, CuMo, and diamond.   The light emitting device according to claim 1, further comprising a carrier on which the submount is mounted and die-bonded to the submount.   The light emitting device according to claim 11, wherein the carrier includes any one of Cu, CuW, Fe alloy, and brass. The light emitting device according to claim 1, wherein the insulating film includes any one of SiO ₂ , SiON, SiN, alumina, BCB, and polyimide.   The light emitting device according to claim 1, wherein the metal film includes Au. A quantum cascade laser,
A first end face that terminates the waveguide mesa, and a second axis that intersects the first axis direction, the waveguide mesa extending in the first axis direction and a substrate on which the waveguide mesa is mounted. A laser structure having a first surface and a second surface arranged in a direction;
A first electrode provided on the first surface of the laser structure;
A second electrode provided on the second surface of the laser structure;
A reflective structure provided on the laser structure;
Including
The laser structure includes a first region, a second region, and a third region arranged on the first axis, the first region includes the first end surface, and the third region includes the first region. Provided between one region and the second region;
The reflective structure includes an insulating film and a metal film,
The metal film has a first edge on the first surface in the first region and a second edge on the second surface in the first region, and the metal film includes the first electrode, Extending on the insulating film from the first edge of the metal film to the second edge of the metal film on the second electrode and the first end face;
The insulating film has a first edge on the first surface in the first region and a second edge on the second surface in the first region, and the first edge and the first edge of the metal film. Located between two edges and the laser structure, the insulating film extending from the first edge of the insulating film to the second edge of the insulating film in contact with the first end face; Quantum cascade laser.

Images