JP5644790B2 - Optical module - Google Patents

Description

  The present invention relates to an optical module.

  Patent Document 1 describes a stem of a semiconductor laser device. Patent Document 2 describes an optical transmission module.

JP-A-8-125259

  In the semiconductor laser device of Patent Document 1, the photodiode receives light from the back surface of the semiconductor laser diode. The semiconductor laser diode is fixed to a stem block having a concave step of a size into which at least a part of the photodiode fixed on the stem base enters. The stem block is integrally formed with the stem base by a metal injection molding method or a lost wax method.

  In Patent Document 2, the pedestal of the semiconductor laser is made of a Si substrate, and a reflection mirror using the (111) plane is formed on the Si substrate. Using this reflection mirror, light from the semiconductor laser is emitted perpendicularly to the mounting surface of the pedestal, and the semiconductor laser, drive circuit, light receiving element, and current-voltage conversion circuit are mounted in the same package in a plane. . This package is sealed by a lens portion to which an optical fiber is connected.

  In Patent Document 1, a semiconductor laser diode chip is mounted on the side surface of a heat sink that extends in the vertical direction from the main surface of the stem base. The light emitting surface of this chip faces in a direction perpendicular to the main surface of the base. According to this aspect, it is possible to direct the emitted laser light in a direction perpendicular to the base main surface without using a separate optical component. However, since the heat sink extends vertically from the main surface of the base, according to the knowledge of the inventors, the heat dissipation performance of the semiconductor laser diode is limited due to the shape and size of the heat sink. For example, the heat sink transfers heat from the semiconductor laser to the stem base in addition to supporting the semiconductor laser chip. The heat that reaches the stem base diffuses in the stem base. In order to align the optical axis of the semiconductor laser with the center of the stem, the heat sink is placed in a limited position (the position of the side surface on which the semiconductor laser and the submount are mounted).

  In Patent Document 2, the semiconductor laser chip is mounted so that light from the semiconductor laser is emitted in a direction parallel to the main surface of the base. Therefore, the optical transmission module disclosed in Patent Document 2 requires a member (heat sink disclosed in Patent Document 1) necessary for mounting the semiconductor laser so that the light from the semiconductor laser is directed in the direction perpendicular to the main surface of the stem base. do not do. For this reason, in the optical transmission module of patent document 2, a submount can be adhere | attached directly on the main surface of a base. However, this direct bonding, according to the knowledge of the inventors, limits the heat dissipation performance of the semiconductor laser diode due to the mounting form of the submount.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical module capable of providing good heat dissipation to a semiconductor laser element in a mounting form using a stem.

  An optical module according to the present invention includes (a) a semiconductor laser element including an active layer, (b) a submount on which the semiconductor laser element is mounted, (c) a first lead terminal, a second lead terminal, and A stem including a base that supports the first lead terminal and the second lead terminal; and (d) a mounting member having a mounting surface on which the submount is mounted and a fixing surface that joins the main surface of the stem; Is provided. The mounting surface of the mounting member is on the opposite side of the fixed surface of the mounting member, and the main surface of the stem is one of the first lead terminal and the second lead terminal on the other side of the main surface. A first area and a second area divided by a first reference axis extending in a direction toward the first direction, and the mounting member extends from the first area to the second area across the first reference axis. The mounting member includes a first region, a second region, and a third region, and the first region, the second region, and the third region are located on the main surface of the stem. The semiconductor laser device is arranged in order in the extending direction of a second reference axis extending in a direction crossing the reference axis, the first region includes a portion having a width larger than the width of the second region, The mounting member via the submount Located in the third region includes a portion having a width greater than a width of the second region.

  According to this optical module, the semiconductor laser element is mounted on the submount, and the submount is mounted on the mounting surface of the mounting member, and the fixing surface of the mounting member is bonded to the main surface of the stem. The mounting surface of the mounting member is on the opposite side of the mounting surface of the mounting member. Heat from the semiconductor laser element is transmitted to the mounting member via the submount.

  The mounting member includes a first region, a second region, and a third region, and the first region of the mounting member includes a portion having a width larger than the width of the second region on which the semiconductor laser element is mounted via the submount. In addition, the third region includes a portion having a width equal to or larger than the width of the second region. After the heat from the semiconductor laser element is transmitted to the second region of the mounting member through the submount, it is diffused into the first region and the third region having a portion having a width larger than the width of the second region. Therefore, in addition to the heat from the semiconductor laser element propagating from the first region, the second region, and the third region of the mounting member to the stem, the first portion includes a portion having a width larger than the width of the second region. Heat is also radiated from the region and the third region to the stem. Therefore, this optical module can provide good heat dissipation to the semiconductor laser element in the mounting using the stem.

  In the optical module according to the present invention, the active layer of the semiconductor laser element can be made of a group III nitride semiconductor.

  This optical module is suitably applied to a group III nitride semiconductor laser device because the group III nitride semiconductor laser device generates a relatively large amount of heat during its operation.

  In the optical module according to the present invention, the semiconductor laser element includes an n-type group III nitride semiconductor region provided on a substrate and a p-type group III nitride semiconductor region provided on the substrate, An active layer is provided between the n-type group III nitride semiconductor region and the p-type group III nitride semiconductor region, and the active layer has an oscillation wavelength of the semiconductor laser device of 400 nm or more and 550 nm or less. It is preferable to be provided.

  According to this optical module, among group III nitride semiconductor laser elements, semiconductor laser elements having an oscillation wavelength in the wavelength range of 400 nm or more and 550 nm or less generate relatively large heat during operation. This optical module is suitably applied to this semiconductor laser element.

  In the optical module according to the present invention, the oscillation wavelength of the semiconductor laser element is preferably in the range of 480 nm to 540 nm.

  According to this optical module, among group III nitride semiconductor laser elements, the oscillation wavelength in the wavelength range of 480 nm to 540 nm is in the wavelength range near the green, and this semiconductor laser element generates a relatively large amount of heat during operation. large. This optical module is suitably applied to this semiconductor laser element.

  In the optical module according to the present invention, it is preferable that an oscillation wavelength of the semiconductor laser element is in a range from 510 nm to 540 nm.

  According to this optical module, among group III nitride semiconductor laser devices, the oscillation wavelength in the wavelength range of 480 nm to 540 nm is in the green wavelength range, and this semiconductor laser device generates relatively little heat during operation. large. This optical module is suitably applied to this semiconductor laser element.

  In the optical module according to the present invention, the semiconductor laser element has a light guide layer, the light guide layer is made of a hexagonal gallium nitride semiconductor, and the light guide layer is in contact with the active layer. The interface between the active layer and the light guide layer is perpendicular to the cm plane defined by the c-axis of the gallium nitride semiconductor and the m-axis of the gallium nitride semiconductor, and the cm It is preferable that the surface is inclined at an angle ALPHA from a reference plane orthogonal to the c-axis in a direction from a c-axis vector indicating the c-axis direction to an m-axis vector indicating the m-axis direction.

  According to this optical module, the group III gallium nitride based semiconductor laser device includes an active layer exhibiting a semipolar surface property applied to long-wavelength light emission.

  In the optical module according to the present invention, it is preferable that the angle ALPHA is in the range of not less than 63 degrees and less than 80 degrees.

  According to this optical module, the above-described angle enables the group III gallium nitride based semiconductor laser device to emit light having a long wavelength.

  In the optical module according to the present invention, it is preferable that the mounting member includes any one of copper and an alloy containing copper.

  According to this optical module, since the mounting member includes either an alloy containing copper or copper, heat dissipation from the heat sink to the stem via the mounting member is improved.

  In the optical module according to the present invention, it is preferable that the mounting member includes one of copper tungsten and copper molybdenum.

  According to this optical module, since the mounting member includes any one of copper tungsten and copper molybdenum, heat dissipation from the heat sink to the stem via the mounting member is excellent.

  In the optical module according to the present invention, it is preferable that the semiconductor laser element is mounted on the main surface of the submount in an epi-down form.

  According to this optical module, mounting in the epi-down mode can transfer heat from the active layer that generates heat due to light emission to the heat sink.

  The optical module according to the present invention may further include a cap provided on the stem and having an optical window. The stem and the cap provide a cavity that accommodates the semiconductor laser element, the submount, and the mounting member, and the thermal conductivity of the mounting member is greater than the thermal conductivity of the submount, and the semiconductor laser element is It is preferable that the optical window is optically coupled to the optical window of the cap through an optical component that changes a traveling direction of laser light from the semiconductor laser element.

  According to this optical module, the semiconductor laser element is optically coupled to the optical window of the cap by changing the traveling direction of the laser light via the optical component. The semiconductor laser element is arranged on the mounting member so as to emit light along a plane extending in a direction parallel to the main surface of the stem. After the heat from the semiconductor laser element propagates through the submount, it propagates through the mounting member having a thermal conductivity larger than the thermal conductivity of the submount in its thickness direction and its extending direction.

  In the optical module according to the present invention, the semiconductor laser element has a waveguide structure including the active layer and a substrate, and the waveguide structure extends in a direction from one end surface to the other end surface of the semiconductor laser element. It is preferable that the semiconductor laser element extends along the main surface of the substrate, and is an end surface emission type in which the waveguide structure extends on the main surface of the substrate. The optical module can further include a mirror for reflecting the laser light emitted from the semiconductor laser element.

  According to this optical module, the mirror can reflect the laser light emitted from the semiconductor laser element.

  In the optical module according to the present invention, the semiconductor laser element has a waveguide structure including the active layer and a substrate, and the semiconductor laser element has the waveguide structure extending on a main surface of the substrate. It can be an end face emission type. The mounting member may further include a mirror for reflecting the laser light emitted from the semiconductor laser element.

  According to this optical module, the mirror of the mounting member can reflect the laser light emitted from the semiconductor laser element.

  In the optical module according to the present invention, the width of the mounting member has a first value on the first reference axis, and the mounting member has a width of the mounting member above the first reference axis. It is preferable that the first reference axis has a portion that changes monotonously from the point in the extending direction of the second reference axis, and the maximum width of the portion of the mounting member is larger than the first value.

  According to this optical module, the mounting member has a portion that monotonously changes as the width of the mounting member moves away from the first reference axis in the extending direction of the second reference axis from a point on the first reference axis. And the maximum width of the portion of the mounting member is greater than the first value. Therefore, the joint area between the mounting member and the stem can be increased.

  In the optical module according to the present invention, the base of the stem has a first opening penetrating from the back surface of the stem to the main surface of the stem, and the first lead terminal passes through the first opening, Preferably, the first lead terminal is supported by the base of the stem via a sealing material, and the side surface of the mounting member includes a curved surface extending away from the edge of the first opening.

  According to this optical module, since the side surface of the mounting member includes a curved surface extending away from the edge of the first opening at a distance of a certain value or more, the bonding area between the mounting member and the stem is avoided while avoiding the first opening. Can be increased.

  In the optical module according to the present invention, the main surface of the stem has an edge of a convex curve, and the side surface of the mounting member is separated from the edge of the main surface of the stem by a distance. It is preferable to have a convex curved surface extending in one area.

  According to this optical module, the side surface of the mounting member has a convex curved surface extending away from the convex curved edge of the main surface of the stem at a distance of a certain value or more, so in the main surface of the stem, The joint area between the mounting member and the stem can be increased by separating the mounting member from the cap.

  In the optical module according to the present invention, the base of the stem has a second opening penetrating from the back surface of the stem to the main surface of the stem, and the second lead terminal passes through the second opening, The second lead terminal is supported by the base of the stem via a sealing material, the main surface of the stem has a curved edge, and the side surface of the mounting member is formed by the second opening. A first curved surface extending in the second area so as to be separated from an edge; and a second curved surface extending in the second area so as to be separated from the edge of the main surface of the stem. Is preferred.

  According to this optical module, the side surface of the mounting member includes a curved surface extending away from the edge of the second opening by a distance of a certain value or more, so that the mounting member and the stem can be joined while avoiding the second opening. The area can be increased. In addition, since the side surface of the mounting member has a convex curved surface so as to be separated from the convex curved edge of the main surface of the stem by a distance of a certain value or more, the mounting member is separated from the cap in the main surface of the stem. It is possible to increase the bonding area between the mounting member and the stem by being spaced apart.

  In the optical module according to the present invention, each of the first lead terminal and the second lead terminal includes the first lead terminal portion and the second lead terminal portion protruding from the upper surface of the submount. The mounting member includes a first portion joining the submount and a second portion adjacent to the first portion, and the thickness of the first portion of the mounting member is the first lead. It is preferably smaller than the height of the terminal portion.

  According to this optical module, the thickness of the first portion of the mounting member is made smaller than the height of the first lead terminal portion, the heat propagation path is shortened, and the second portion adjacent to the first portion is also formed. Heat propagates. The mounting member can increase the bonding area between the mounting member and the stem to promote heat propagation.

  In the optical module according to the present invention, the mounting member includes a first recess and a second recess provided on the main surface of the stem in the direction of the first reference axis, and an upper surface of the main surface of the stem. It is preferable that the first convex portion and the second convex portion provided in the direction of the second reference axis are included.

  According to this optical module, the first concave portion and the second concave portion are arranged in the direction of the first reference axis, and the first convex portion and the second convex portion are arranged in the direction of the second reference axis. In this way, the area of the joint between the mounting member and the stem can be increased while avoiding the lead terminals.

  In the optical module according to the present invention, the mounting member is preferably made of a metal plate.

  According to this optical module, since the mounting member is made of a metal plate, heat from the semiconductor laser element can be widely propagated using the plate-like member. More areas of the stem can be actively used for heat dissipation.

  As described above, according to the present invention, an optical module capable of providing good heat dissipation to a semiconductor laser element in a mounting form using a stem is provided.

FIG. 1 is a drawing schematically showing an optical module according to the present embodiment. FIG. 2 is a drawing schematically showing a part of the optical module according to the present embodiment. FIG. 3 is a top view showing the stem and the mounting member according to the present embodiment. FIG. 4 is a drawing schematically showing the optical module according to the present embodiment. FIG. 5 is a drawing schematically showing an example of a semiconductor laser element for the optical module according to the present embodiment. FIG. 6 is a drawing showing a laser diode structure in Example 1. FIG. 7 is a drawing schematically showing an optical module including a semiconductor laser device mounted on a side surface of a metal pedestal. FIG. 8 is a diagram illustrating an optical module in an example of a vertical mounting form. FIG. 9 is a diagram showing an optical module in a horizontal mounting form in an example according to the present embodiment. FIG. 10 is a drawing showing the relationship between the thickness of the mounting member and the thermal resistance in the present embodiment.

  An embodiment of the present invention relating to an optical module will be described. Where possible, the same parts are denoted by the same reference numerals.

  FIG. 1 is a drawing schematically showing an optical module according to the present embodiment. FIG. 2 is a drawing schematically showing a part of the optical module according to the present embodiment. Referring to FIG. 1, the optical module 1 includes a submount 3, a package 5, a mounting member 9, and a semiconductor laser element 11. The semiconductor laser element 11 includes an active layer. The submount 3 carries the semiconductor laser element 11. The package 5 includes a stem 10a and a cap 10b. The stem 10a includes a base 77a, a first lead terminal 77b, and a second lead terminal 77c. The base 77a supports the first lead terminal 77b and the second lead terminal 77c. The mounting member 9 has a mounting surface 9a on which the submount 3 is mounted and a fixed surface 9b that joins the main surface 10c of the stem 10a. The mounting surface 9a of the mounting member 9 is on the opposite side of the fixed surface 9b.

  Referring to FIG. 2A, the main surface 10c of the stem 10a has a first area 10d and a second area 10e, and the first lead terminal 77b and the second lead terminal 77c on the main surface 10c. The first area 10d and the second area 10e are divided by the first reference axis RA1 extending in the direction from one side to the other side. The mounting member 9 extends from the first area 10d to the second area 10e across the first reference axis RA1. The mounting member 9 includes a first region 9c, a second region 9d, and a third region 9e. The first region 9c, the second region 9d, and the third region 9e are sequentially arranged in the extending direction of the second reference axis RA2 extending in the direction intersecting the first reference axis RA1 on the main surface 10c of the stem 10a. Has been. The first region 9c includes a portion having a width larger than that of the second region 9d. For example, the maximum value in the width of the second region 9d is smaller than the maximum value in the width of the first region 9c. For example, the minimum value in the width of the second region 9d is smaller than the maximum value in the width of the first region 9c. The semiconductor laser element 11 is positioned on the mounting member 9 via the submount 3. The semiconductor laser element 11 is positioned on at least one of the first region 9 c and the second region 9 d of the mounting member 9 via the submount 3, or the semiconductor laser element 11 is mounted on the mounting member via the submount 3. 9 is located on at least one of the third region 9e and the second region 9d. The semiconductor laser element 11 is located on the second region 9 d of the mounting member 9 via the submount 3. The third region 9e of the mounting member 9 includes a portion having a width equal to or greater than the width 9d of the second region. The third region 9e may include a portion having a width larger than that of the second region 9d. For example, the maximum value in the width of the second region 9d is smaller than the maximum value in the width of the third region 9e. For example, the minimum value in the width of the second region 9d is smaller than the maximum value in the width of the third region 9e.

  According to the optical module 1, the semiconductor laser element 11 is mounted on the submount 3, and the submount 3 is mounted on the mounting surface 9 a of the mounting member 9. The mounting surface 9b of the mounting member 9 is joined to the main surface 10c of the stem 10a, and the mounting surface 9a of the mounting member 9 is on the opposite side of the fixing surface 9b. Heat from the semiconductor laser element 11 is transmitted to the mounting member 9 through the submount 3.

  When the mounting member 9 including the first region 9c, the second region 9d, and the third region 9e is used, the first region 9c of the mounting member 9 is the second region 9d in which the semiconductor laser element 11 is located via the submount 3. The third region 9e includes a portion having a width equal to or larger than that of the second region 9d. After the heat from the semiconductor laser element 11 is transmitted to the second region 9d of the mounting member 9 through the submount 3, the first region 9c and / or the second region having a portion having a width larger than the width of the second region 9d. It diffuses into the three areas 9e. Therefore, in addition to the heat from the semiconductor laser element 11 propagating from the second region 9d of the mounting member 9 to the first region 9c and the third region 9e, a portion having a width larger than the width of the second region 9c. The heat is dissipated from the first region 9a and the third region 9e including the heat to the stem 10a. Therefore, the optical module 1 can provide good heat dissipation to the semiconductor laser element 11 in mounting using the stem 10a.

  In the optical module 1, the active layer of the semiconductor laser device 1 can be made of a group III nitride semiconductor. Since the group III nitride semiconductor laser device generates a relatively large amount of heat during its operation, the group III nitride semiconductor laser device is preferably applied to a group III nitride semiconductor laser device.

  The optical module 1 includes a submount 3 and a semiconductor laser element 11. The submount 3 has a mounting surface 3a and a back surface 3b. The material of the submount 3 is made of, for example, AlN, GaN, SiC, diamond, or the like. The mounting surface 3a of the submount 3 is provided so as to mount a device. The thickness of the submount 3 is preferably 100 μm or more and 400 μm or less, for example. The thermal conductivity of the submount 3 is preferably 100 W / (m · K) or more, for example. An electrode 3c can be provided on the mounting surface 3a of the submount 3 if necessary. A nitride semiconductor light emitting device such as a semiconductor laser device 11 is mounted on the mounting surface 3 a of the submount 3.

The mounting member 9 is made of metal, and the thermal conductivity of the mounting member 9 is preferably larger than the thermal conductivity of the submount 3. The mounting member 9 preferably includes, for example, any one of copper and an alloy containing copper. According to the optical module 1, the mounting member 9 includes either an alloy containing copper or copper, and thus heat radiation from the submount 3 to the stem 10 a via the mounting member 9 is improved. The mounting member 9 preferably contains either copper tungsten or copper molybdenum. According to this optical module 1, since the mounting member 9 contains either copper tungsten or copper molybdenum, heat dissipation from the heat sink to the stem via the mounting member is excellent.
Material name, thermal conductivity.
Copper: 398 W / (m · K).
Copper tungsten: 230 to 270 W / (m · K).
Copper molybdenum: 160 to 290 W / (m · K).
The thermal conductivity is preferably 160 (m · K) or more, for example, and the thermal conductivity is more preferably 230 (m · K) or more, for example.

  In the stem 10a, the base 77a is a metal, and this metal can be, for example, iron (Fe). Base 77a includes a through hole extending in a direction from the front surface (main surface 10c) to the back surface, and each of lead terminals 77b and 77c is supported by the through hole. A space between the lead terminals 77b and 77c and the through hole is filled with a sealing material (sealing glass). The mounting member 9 avoids a through hole for the lead terminals 77b and 77c and extends between the lead terminal 77b and the lead terminal 77c. In this embodiment, the second region 9d is defined as a portion located between the openings of the two through holes. In the optical module 1, the semiconductor laser element 11 mounted on the upper surface of the mounting member 9 on the metal base 77a is firmly fixed to the submount 3 with a conductive adhesive. The semiconductor laser element 11 can have a ridge structure, but the present embodiment is not limited to this. A lens cap 10b for holding a lens 74 for providing light from the semiconductor laser element 11 to the outside is provided on the stem 10a. The stem 10a and the lens cap 10b constitute a coaxial package. In the optical module 1, the stem 10 a and the cap 10 b provide a cavity for housing the submount 3, the mounting member 9, and the semiconductor laser element 11.

  2B, the semiconductor laser element 11 is optically coupled to the optical window of the cap 10b via an optical component (for example, a mirror 75) that changes the traveling direction of the laser light from the semiconductor laser element 11. It is preferred that This optical component is mounted on the mounting member 9.

  In the optical module 1, the optical component can include a mirror 75 that reflects the laser beam LB1 emitted from the semiconductor laser element 11 and provides the laser beam LB1 to the lens 74 of the cap 10b. The mirror 75 is provided in the second region 9d (for example, approximately the center of the stem 10a) of the mounting member 9.

  The thermal conductivity of the mounting member 9 is preferably larger than the thermal conductivity of the stem base. The metal base 77a is made of iron, for example, and the metal portion of the lens cap 10b is also made of iron. As already described, the mounting member 9 is made of, for example, copper having excellent thermal conductivity, for example. The lead terminal 77b is connected to an electrode (for example, a cathode electrode) of the semiconductor laser element 11 through a bonding wire 79b. The lead terminal 77c is connected to the electrode layer 3c on the mounting surface 3a of the submount 3 via a bonding wire 79c. For example, the stem 10a may include additional lead terminals that are connected to a metal base 77a.

  In the optical module 1, the semiconductor laser element 11 is optically coupled to an optical component and optically coupled to an optical window of the cap. The semiconductor laser element 11 travels toward the optical window (for example, the lens 74) of the cap while changing the traveling direction of the laser light LD1 through the optical component. The semiconductor laser element 11 is disposed on the mounting member 9 so as to emit light along a plane extending in a direction parallel to the main surface 10c of the stem 10a. After the heat from the semiconductor laser element 11 propagates through the submount 3, it propagates through the mounting member 9 having a thermal conductivity larger than that of the submount 3 in the thickness direction and the extending direction thereof.

  In the optical module 1, the semiconductor laser element 11 is preferably mounted on the main surface (mounting surface 3 a) of the submount 3 in an epi-down form (for example, a p-down form). The epi-down mounting can transfer heat from the active layer that generates heat due to light emission to the heat sink.

  Next, the mounting member 9 will be described. FIG. 3 is a top view showing the stem 10 a and the mounting member 9.

  Referring to FIG. 3, in one form of the optical module 1, the width of the mounting member 9 has a first value W1 on the first reference axis RA1. The mounting member 9 has a first reference axis RA1 in which the width of the mounting member 9 (the length in the extending direction of the first reference axis RA1) extends from the point on the first reference axis RA1 to the extending direction of the second reference axis RA2. It is possible to have portions 9f and 9g that change monotonously as they move away from each other. In the mounting member 9, the maximum width WMAX1 (WMAX2) in the portion 9f (9g) is larger than the first value W1. In this embodiment, the mounting member 9 has a portion 9f (9g) in which the width of the mounting member 9 changes monotonously, and the maximum width WMAX1 (WMAX2) in the portion 9f (9g) of the mounting member 9 is the first. Therefore, the joint area between the mounting member 9 and the stem 10a can be increased.

  In one form of the optical module 1, the base 77a has a first opening 77d, and the first opening 77d penetrates from the main surface 10c of the stem 10a to the back surface. The first lead terminal 77b passes through the first opening 77d, and the first lead terminal 77b is supported by the base 77a through the sealing material 77f. The side surface 9h of the mounting member 9 preferably includes a curved surface that extends away from the edge of the first opening 77d by a distance of a certain value (for example, 0.1 mm). When the side surface 9h of the mounting member 9 is a curved surface, it is possible to spread two-dimensional heat while avoiding the first opening 77d, and to increase the bonding area between the mounting member 9 and the stem 10a.

  In one form of the optical module 1, the main surface 10c of the stem 10a has an edge of a convex curve. The side surface 9i of the mounting member 9 preferably has a convex curved surface extending to the first area 10d so as to be separated from the edge 10f of the main surface 10c of the stem 10a by a distance (for example, 1 mm) greater than a certain value. It is. When the side surface 9i of the mounting member 9 has a convex curved surface, the mounting member 9 is spaced from the cap 10b in the main surface 10c of the stem 10a, thereby enabling two-dimensional heat spread. At the same time, the bonding area between the mounting member 9 and the stem 10a can be increased.

  In one form of the optical module 1, the base 77a of the stem 10a has a second opening 77e, and the second opening 77e penetrates from the main surface 10c of the stem 10a to the back surface. The second lead terminal 77c passes through the second opening 77e, and the second lead terminal 77c is supported by the base 77a via the sealing material 77f. The main surface 10c of the stem 10a has a curved edge 10g. The side surface of the mounting member 9 preferably has a first curved surface 9j and a second curved surface 9k. The first curved surface 9k extends in the second area 10e so as to be separated from the edge of the second opening 77e by a distance of a certain value or more, and the second curved surface 9k is the main surface of the stem 10a by a distance of a certain value or more. The second area 10e extends away from the edge 10g of the surface 10c. According to this optical module 1, since the side surface of the mounting member 9 includes the curved surface 9k, it is possible to spread heat in two dimensions while avoiding the second opening 77e, and the bonding area between the mounting member 9 and the stem 10a. Can be increased. Further, when the side surface of the mounting member 9 has a convex curved surface 9j, the mounting member 9 is spaced from the cap 10b in the main surface 10c of the stem 10a, and two-dimensional heat spread is possible. In addition, the joint area between the mounting member 9 and the stem 10a can be increased.

  In one form of the optical module 1, referring to part (a) of FIG. 4, the first lead terminal 77b and the second lead terminal 77c are respectively the first lead terminal part 77b protruding from the upper surface of the base 77a. And a second lead terminal portion 77c. Referring to FIG. 4B, the mounting member 9 includes a first portion 9m for joining the submount 3, and a second portion 9n adjacent to the first portion 9m. The thickness D3 of the first portion 9m of the mounting member 9 is preferably smaller than the height H1 of the first lead terminal portion 77b. For example, the height H1 of the first lead terminal portion 77b and the second lead terminal portion 77c. The height H2 is smaller than the height which is not higher. The thickness D3 of the first portion 9m of the mounting member 9 is made smaller than the height H1 of the first lead terminal portion 77b to shorten the heat propagation path, and also to the second portion 9n adjacent to the first portion 9m. Heat propagates. The mounting member 9 can increase the bonding area between the mounting member 9 and the stem 10a and diffuse heat to promote heat propagation. For example, the height H1 of the first lead terminal portion 77b can be equal to or lower than the height H2 of the second lead terminal portion 77c.

  Referring to part (b) of FIG. 4, in one form of the optical module 1, the mounting member 9 includes a first recess 8c and a second recess provided on the main surface 10c of the stem 10a in the direction of the first reference axis RA1. It is preferable to include a recess 8d. Accordingly, it is possible to increase the bonding area between the mounting member 9 and the stem 10 and promote heat transfer while avoiding the openings 77d and 77e for the lead terminals. The mounting member 9 preferably includes a first convex portion 8a and a second convex portion 8b provided in the direction of the second reference axis RA2 on the main surface 10c of the stem 10a. Thereby, the joining area of the mounting member 9 and the stem 10 can be increased. Further, the first concave portion 8c and the second concave portion 8d are arranged in the direction of the first reference axis RA1, and the first convex portion 8a and the second convex portion 8b are arranged in the direction of the second reference axis RA2. When the mounting member 9 is disposed on the main surface 10c of the stem 10a, it is possible to increase the bonding area between the mounting member 9 and the stem 10a and promote the lateral spread of heat while avoiding the lead terminals 77b and 77c. .

  In one form of the optical module 1, the mounting member 9 is preferably made of a metal plate. When the mounting member 9 is made of a metal plate, the heat from the semiconductor laser element 11 can be widely propagated using a plate-like member. More areas of the stem 10a can be actively used for heat dissipation.

  Alternatively, another form of the mounting member 9 can further include a mirror for reflecting the laser light emitted from the semiconductor laser element 11. The mirror of the mounting member reflects the laser light emitted from the semiconductor laser element 11, and the reflected light is directed to the lens of the cap 10b.

  In this embodiment, the optical module 1 is mounted on the stem 10a. The semiconductor laser element 11 can be mounted on the mounting surface 3a of the submount 3 in a so-called p-down configuration. In the p-down configuration, the anode of the semiconductor laser element 11 faces the submount mounting surface 3a. The anode is at a positive potential with respect to the cathode.

  The optical module 1 (or the nitride semiconductor laser device) can further include an adhesive member (member 6 in FIG. 1) provided between the semiconductor laser element 11 and the submount 3. The adhesive member is used for mounting the semiconductor laser element 11 on the mounting surface 3 a of the submount 3. The adhesive member 6 has conductivity. When the semiconductor laser element 11 is mounted on the mounting surface 3a of the submount 3, the semiconductor laser element 11 is heated. This heating may cause deterioration and fluctuation of the electrical characteristics of the electrode 15 of the semiconductor laser element 11. In a preferred embodiment, the adhesive member 6 is preferably at least one of AuSn, SnAgCu, SnAg, and BiSn. Since SnAgCu, SnAg, and BiSn have a low melting point, it is possible to reduce degradation of electrode characteristics due to heat during mounting. In one embodiment, the semiconductor laser element 11 is fixed to a mounting component via a solder material, and this solder material preferably contains AuSn that can provide high reliability.

The submount 3 has a mounting surface 3a for mounting a device. The thermal expansion coefficient of the submount 3 can be in the range of 2.5 × 10 ⁻⁶ / K to 6.5 × 10 ⁻⁶ / K. The value of this range in the thermal expansion coefficient is preferred because near a thermal expansion coefficient of the nitride semiconductor 3 × ^{10 -6} / K or 6 × ^{10 -6} / K.

  The semiconductor laser element 11 is located on the electrode 3c of the submount 3. In the example of p-down mounting, the anode of the nitride semiconductor light emitting element is bonded to the electrode 3c. The electrode 3c includes a metal layer. The electrode 3c may be connected to the lead terminal via a conductive member such as a bonding wire. Further, the cathode of the nitride semiconductor light emitting device 11 may be connected to the lead terminal of the stem through a conductive member such as a bonding wire. The semiconductor laser element 11 is preferably fixed to the electrode 3 c of the submount 3 by an adhesive member 9.

  FIG. 5 is a drawing schematically showing the optical module according to the present embodiment. Referring to FIG. 5, a semiconductor light emitting device made of nitride is shown, and a semiconductor laser device 11 made of group III nitride is shown as the semiconductor light emitting device. The optical module 10 includes a semiconductor laser element 11. The semiconductor laser element 11 includes a laser structure 13 and electrodes 15 and 41.

  A ridge type structure is applied to the semiconductor laser element 11. The group III nitride semiconductor laser device 11 includes a laser structure 13 and an electrode 15. The laser structure 13 includes a substrate 17 on which an epitaxial semiconductor stack (hereinafter referred to as “semiconductor stack”) 19 made of a group III nitride semiconductor 19 is mounted. The semiconductor stack 19 is provided on the main surface 17 a of the substrate 17. The electrode 15 is provided on the semiconductor stack 19. The substrate 17 is made of a hexagonal gallium nitride semiconductor and has a main surface 17a and a back surface 17b. The main surface 17a of the substrate 17 is inclined with respect to a first reference plane (for example, the surface Sc) orthogonal to the c-axis of the gallium nitride semiconductor of the substrate 17, and has a polarity characteristic different from the polarity of the c-plane. Or may have c-plane polarity. The semiconductor stack 19 includes an active layer 25. In one embodiment, the active layer 25 is provided such that the oscillation wavelength of the group III nitride semiconductor laser device 11 is in the range of 400 nm to 550 nm. The c-axis (axis directed in the direction of the vector VC) in the semiconductor stack 19 is inclined with respect to the normal axis NX with respect to the main surface 17a of the substrate 17.

  According to this optical module 1, an oscillation wavelength within a range of 400 nm or more and 550 nm or less requires high input power to the semiconductor laser element 11.

  In the optical module 1, the substrate 17 of the semiconductor laser element 11 can be made of a gallium nitride based semiconductor, for example, preferably made of GaN.

  In one form of the semiconductor laser element 11, the main surface of the gallium nitride semiconductor of the substrate 17 may have a slight off angle from the c-plane or the c-plane. Alternatively, in another form of the semiconductor laser device 11, the c-axis (vector VC) of the gallium nitride semiconductor of the substrate 17 is inclined from the c-axis of the group III nitride semiconductor toward the a-axis or m-axis. Can do. When the III-nitride semiconductor laser device 11 is fabricated using the c-axis substrate 17 inclined in the a-axis or m-axis direction, the III-nitride semiconductor laser device 11 has an anisotropic thermal expansion coefficient. Have. In this semiconductor laser device, the semiconductor stack 19 includes a p-type group III nitride semiconductor (for example, “layer 33”) with which the electrode 15 is in contact, and the main surface 17a of the substrate 17 is a first reference surface (for example, Sc). It is preferable to incline at an angle of 10 degrees or more. According to the optical module 10 and the nitride semiconductor laser device 1, since the semiconductor stack 19 is provided on the main surface 17 a of the substrate 17, the bonding surface 30 a between the electrode 15 and the p-type gallium nitride based semiconductor layer is also the reference surface ( For example, it is inclined at an angle of 10 degrees or more with respect to the surface Sc). Further, the joint surface 30a is also inclined at an angle of 170 degrees or less with respect to a reference surface (for example, the surface Sc).

  When the semipolar surface 17a of the substrate 17 is inclined with respect to the c-axis of the hexagonal gallium nitride semiconductor at an angle ALPHA within a range of not less than 63 degrees and not more than 80 degrees in the m-axis direction, the electrode 15 and the electrode 15 The interface 30a with the p-type contact layer 33 that contacts with each other is also inclined at the angle ALPHA described above.

  In the above angle range, the p-side electrode 15 of the group III nitride semiconductor laser device 11 is liable to cause deterioration of current-voltage characteristics. In an example of the deterioration of the current-voltage characteristic, the good ohmic characteristic is lost, and the current-voltage characteristic of the electrode 15 is deteriorated so as to exhibit a Schottky characteristic or a characteristic close to the Schottky characteristic. According to the knowledge of the inventor, such electrode characteristic deterioration occurs remarkably in the electrode 15 formed on the semipolar surface of the gallium nitride semiconductor. When the group III nitride semiconductor laser device 11 is exposed to thermal stress due to a process for forming an electrode, for example, the current-voltage characteristics of the electrode 15 are easily deteriorated. However, in the mounting form using the mounting member 9 having high thermal conductivity, the characteristic deterioration (that is, thermal deterioration) of the electrode after mounting can be reduced.

  Referring to FIG. 5, the electrode 15 is provided on the semiconductor stack 19 of the laser structure 13. The semiconductor stack 19 includes a first cladding layer 21, a second cladding layer 23, and an active layer 25. The first cladding layer 21 is formed of a first conductivity type group III nitride semiconductor region (for example, an n-type group III nitride semiconductor region or an n-type gallium nitride based semiconductor), for example, n-type AlGaN, n-type InAlGaN, or the like. Become. The second cladding layer 23 is made of a second conductivity type group III nitride semiconductor region (for example, a p-type group III nitride semiconductor region or a p-type gallium nitride semiconductor), for example, p-type AlGaN, p-type InAlGaN, or the like. Become. The active layer 25 is provided between the first cladding layer 21 and the second cladding layer 23. The active layer 25 includes a gallium nitride based semiconductor layer, and this gallium nitride based semiconductor layer is, for example, a well layer 25a. The active layer 25 includes a barrier layer 25b made of a gallium nitride semiconductor, the well layer 25a is provided between the barrier layers 25b, and the layers 25a and 25b are alternately arranged. The well layer 25a is made of, for example, InGaN, and the barrier layer 25b is made of, for example, GaN, InGaN, or the like. The active layer 25 may include a quantum well structure. The first cladding layer 21, the second cladding layer 23, and the active layer 25 are arranged along the normal axis NX of the semipolar main surface 17a. Use of the semipolar main surface 17a is suitable for generation of light having a wavelength of 480 nm or more and 540 nm or less. According to the nitride semiconductor laser device 1 and the optical module 10, the group III nitride semiconductor laser element 11 can provide laser oscillation within the above wavelength range indicating light of green and its adjacent color. In the semiconductor laser element 11, the active layer 25 is preferably provided so as to have an oscillation wavelength in the range of 510 nm or more and 540 nm or less. According to the nitride semiconductor laser device 1 and the optical module 10, the semiconductor laser element 11 can provide laser oscillation within the above wavelength range indicating green light.

  In the semiconductor laser device 11 of the present embodiment, the c-axis of the hexagonal group III nitride semiconductor is inclined in the direction of the m-axis of the hexagonal group III nitride semiconductor. Therefore, the laser structure 13 includes a first end face 27 and a second end face 29 that intersect the mn plane defined by the m-axis and the normal axis NX of the hexagonal group III nitride semiconductor. Note that the c-axis of the hexagonal group III nitride semiconductor can be inclined in the direction of the a-axis of the hexagonal group III nitride semiconductor. At this inclination, the first end face of the laser structure 13 is formed. 27 and the second end face 29 are formed of a fractured surface that intersects with the a-n plane defined by the a-axis and the normal axis NX of the hexagonal group III nitride semiconductor and is not a cleavage plane. Or the 1st end surface 27 and the 2nd end surface 29 may cross | intersect the surface orthogonal to both the main surface 17a of the board | substrate 17, and an mn surface (or an ann surface).

  In FIG. 5, an orthogonal coordinate system S and a crystal coordinate system CR are drawn. The normal axis NX is directed in the direction of the Z axis of the orthogonal coordinate system S. The main surface 17a extends in parallel to a predetermined plane defined by the X axis and the Y axis of the orthogonal coordinate system S. Further, a representative c-plane Sc is drawn. The c-axis of the hexagonal group III nitride semiconductor of the substrate 17 is inclined at an angle ALPHA greater than zero with respect to the normal axis NX in the m-axis direction of the hexagonal group III nitride semiconductor.

  The semiconductor laser element 11 further includes an insulating film 31. The insulating film 31 covers the surface 19 a of the semiconductor stack 19 of the laser structure 13, and the semiconductor stack 19 is located between the insulating film 31 and the substrate 17. The substrate 17 is made of a hexagonal group III nitride semiconductor. The insulating film 31 has an opening 31a. The opening 31a extends in the direction of the intersection line between the surface 19a of the semiconductor stack 19 and the mn plane, and has, for example, a stripe shape. The electrode 15 is in contact with the surface 19a (for example, the second conductivity type contact layer 33) of the semiconductor stack 19 through the opening 31a, and extends in the direction of the crossing line. In the semiconductor laser device 11, the laser waveguide includes the first cladding layer 21, the second cladding layer 23, and the active layer 25, and extends in the intersecting line direction. A pad electrode 16 may be provided on the electrode 15 and the insulating film 31.

  The main surface 17a of the substrate 17 is made of a hexagonal gallium nitride semiconductor, and the main surface 17 of the substrate 17 has a semipolar surface inclined with respect to the c-axis of the hexagonal gallium nitride semiconductor. The semiconductor stack 19 includes a plurality of semiconductor layers 21, 20, 23, 33 that are epitaxially grown on the main surface 17 a of the substrate 17. According to this nitride semiconductor laser device, a semiconductor stack can be fabricated on the semipolar plane of a hexagonal gallium nitride semiconductor. The main surface 17a of the substrate 17 is preferably made of hexagonal gallium nitride. According to this nitride semiconductor laser device 1, it is possible to produce a semiconductor stack on GaN having good crystal quality.

  In the semiconductor laser element 11, as already described, when the c-axis is inclined in the m-axis direction, the first end face 27 and the second end face 29 are formed with the m-axis and method of the hexagonal group III nitride semiconductor. Intersects the mn plane defined by the line axis NX (or when the c-axis is inclined in the direction of the a-axis, the first end face 27 and the second end face 29 are formed of a hexagonal group III nitride semiconductor. intersects the a-n plane defined by the m-axis and the normal axis NX). The laser resonator of the semiconductor laser element 11 includes first and second end faces 27 and 29, and a laser waveguide (in the direction of the waveguide axis from one of the first end face 27 and the second end face 29 to the other end). The waveguide structure is extended. The laser structure 13 includes a first surface 13a and a second surface 13b, and the first surface 13a is a surface opposite to the second surface 13b. These end faces can be cleaved faces or split sections, depending on the c-axis tilt direction and the laser waveguide extension direction. The semiconductor laser element 11 can be of an edge emission type in which a waveguide structure including an active layer provided on a substrate extends on the main surface of the substrate. The semiconductor laser element 11 can be installed in the horizontal direction with respect to the main surface 10c of the stem 10a, and generates laser light in the horizontal direction. The first and second end surfaces 27 and 29 extend from the edge 13c of the first surface 13a to the edge 13d of the second surface 13b. In the present embodiment, the laser waveguide extends along the nm plane, and the first and second end faces 27 and 29 are the conventional cleavage planes such as the c-plane, m-plane, or a-plane. Unlike, it consists of a split section for an optical resonator. The substrate 17 can be made of, for example, GaN. When a substrate made of the gallium nitride semiconductor is used, end faces 27 and 29 that can be used as resonators can be obtained.

  According to this semiconductor laser device 11, the first and second end faces 27 and 29 constituting the laser resonator intersect with the mn plane. Therefore, it is possible to provide a laser waveguide extending in the direction of the intersecting line between the mn plane and the semipolar plane 17a. Therefore, the semiconductor laser element 11 has a laser resonator that enables a low threshold current.

  Dielectric multilayer films 43a and 43b provided on at least one of the first and second end faces 27 and 29 or on each of them may be further provided. An end face coat can also be applied to these end faces 27 and 29. With the dielectric multilayer films 43a and 43b, the reflectance can be adjusted by end face coating.

  The semiconductor laser element 11 includes an n-side light guide layer 35 and a p-side light guide layer 37. The n-side light guide layer 35 includes a first portion 35a and a second portion 35b, and the n-side light guide layer 35 is made of, for example, GaN, InGaN, or the like. The p-side light guide layer 37 includes a first portion 37a and a second portion 37b, and the p-side light guide layer 37 is made of, for example, GaN, InGaN, or the like. The carrier block layer 39 is provided, for example, between the first portion 37a and the second portion 37b.

  In the semiconductor laser device 11, the interface 30b between the light guide layer 35 and the active layer 25 provided on the main surface made of a gallium nitride semiconductor is formed by the c-axis of the gallium nitride semiconductor and the m-axis of the gallium nitride semiconductor. It is orthogonal to the defined cm plane. The interface 30b between the active layer 25 and the light guide layer 35 is inclined at an angle ALPHA from the c-plane orthogonal to the c-axis in a direction from the c-axis vector indicating the c-axis direction to the m-axis vector indicating the m-axis direction. Can be made. If the mounting form according to the present embodiment is effective, one form of the semipolar plane is inclined from the c-plane in the direction from the c-axis vector to the m-axis vector, for example.

  Another electrode 41 is provided on the back surface 17b of the substrate 17, and the electrode 41 covers the back surface 17b of the substrate 17, for example. The light guide layers 35 and 37 and the active layer 25 constitute the light emitting layer 20.

  The semiconductor stack 19 includes a light guide layer 35. The light guide layer 35 is in contact with the active layer 25, and the interface 30b between the active layer 25 and the light guide layer 35 is c orthogonal to the c-axis of the gallium nitride semiconductor. The angle ALPHA can be inclined from the surface. When the interface 30b between the active layer 25 and the light guide layer 35 is inclined as described above, the angle ALPHA defines the plane orientation of the active layer 25 in the group III nitride semiconductor laser device 11. For example, when the angle ALPHA is in the range of not less than 63 degrees and less than 80 degrees, the group III gallium nitride semiconductor laser element can emit light with a long wavelength. Further, the above angle is suitable for manufacturing a group III nitride semiconductor laser that generates light of green and adjacent wavelengths.

  In the semiconductor laser device 11, the semiconductor stack 19 includes a first conductive group III nitride semiconductor region (for example, semiconductor layers 21 and 35 a), a light emitting layer 20, and a second conductive type group III nitride semiconductor region (for example, semiconductor layer 37 a, 23, 33). The first conductivity type group III nitride semiconductor region (for example, semiconductor layers 21 and 35a), the light emitting layer 20, and the second conductivity type group III nitride semiconductor region (for example, semiconductor layers 37b, 23, and 33) are in the direction of the normal axis NX. They are arranged in order. The electrode 15 is in contact with the main surface of the second conductivity type group III nitride semiconductor region (for example, the semiconductor layers 37a, 23, and 33). The first conductivity type group III nitride semiconductor region (for example, the semiconductor layers 21 and 35a), the light emitting layer 20, and the second conductivity type group III nitride semiconductor region (for example, the semiconductor layers 37b, 23, and 33) each have a normal axis NX. Extends along first to third reference planes R1, R2, and R3 orthogonal to each other.

  In the optical module 1, the substrate 17 is provided between the semiconductor stack 19 of the semiconductor laser element 11 and the submount 3. In the optical module 1, the semiconductor laser element 11 is mounted in a so-called p-down configuration. The substrate 17 is farther from the main surface 3 a of the submount 3 than the active layer 25. The optical module 1 is formed through a thermal process via an adhesive member 7 (for example, solder) located between an electrode (for example, the electrode 15) of the semiconductor laser element 11 and the main surface 3a of the submount 3. Includes bonding.

  In the optical module 1, the nonpolar or semipolar main surface 17a is preferably inclined at an angle ALPHA within a range of 10 degrees or more and 170 degrees or less with respect to the c-axis of the hexagonal gallium nitride semiconductor. . According to this optical module 1, an active layer suitable for light emission in the green region can be produced in the above angle range. The polar main surface 17a can be in the range of 0 degrees to 10 degrees.

  When the semipolar main surface 17a of the substrate 17 is inclined at an angle ALPHA within a range of 10 degrees to 170 degrees in the m-axis direction with respect to the c-axis of the hexagonal gallium nitride semiconductor, the active layer 25 The peak wavelength of light emission can be in the range of 500 nm to 540 nm. Since the semiconductor stack 19 of the group III nitride semiconductor laser device 11 is formed on the main surface 17a which is not the c-plane, the group III nitride semiconductor laser device 11 emits light in the above wavelength range (for example, green light emission). Can be provided.

  In the semiconductor laser device 11, the substrate 17 has a semipolar main surface 17a of group III nitride. The epitaxial layer structure of the semiconductor laser element 11 preferably includes an active layer provided on the semipolar main surface 17a of the substrate 17 and made of a group III nitride semiconductor. The semiconductor laser element 11 is produced on the semipolar surface 17a. In order to emit light from the light emitting element, it is necessary to input a large amount of electric power. Therefore, it is important to discharge heat during operation to the outside of the optical module. The ability to reduce the temperature during the operation of the group III nitride semiconductor optical device can avoid a further large amount of power input and can reduce a decrease in operating performance.

  Among the semiconductor laser elements 11, a Group III nitride laser diode having an oscillation wavelength in the wavelength range of 400 nm to 550 nm generates a relatively large amount of heat during operation. This optical module 1 is suitably applied to this laser diode. The oscillation wavelength of the semiconductor laser element 11 is preferably in the range of 480 nm to 540 nm. Among group III nitride semiconductor laser elements, the oscillation wavelength in the wavelength range of 480 nm to 540 nm is in the wavelength range near green, and this laser diode generates a relatively large amount of heat during operation. This optical module 1 is suitably applied to this group III nitride laser diode. Furthermore, the oscillation wavelength of the semiconductor laser element 11 is preferably in the range of 510 nm or more and 540 nm or less. Among group III nitride semiconductor laser elements, the oscillation wavelength in the wavelength range of 480 nm to 540 nm is in the green wavelength range, and this laser diode generates a relatively large amount of heat during operation. This optical module 1 is suitably applied to this laser diode.

Example 1
An embodiment of a nitride semiconductor laser device will be described. A group III nitride semiconductor laser device is prepared. In this example, a group III nitride semiconductor laser device is prepared by forming the following steps.

(Production of Group III Nitride Semiconductor Laser Device)
The laser diode structure shown in FIG. 6 is produced. A GaN wafer 90 with the c-axis turned off by 75 degrees in the m-axis direction was prepared. The plane orientation of the main surface of the GaN wafer 90 is the {20-21} plane. After the GaN wafer 90 is placed in the growth furnace, heat treatment is performed in an atmosphere of ammonia and hydrogen. The heat treatment temperature is 1100 degrees Celsius, and the heat treatment time is about 10 minutes. After the heat treatment, TMG (98.7 μmol / min), TMA (8.2 μmol / min), NH 3 (6 slm), SiH ₄ are supplied to the growth furnace, and the n-type AlGaN layer 91 for the cladding layer is formed as a GaN wafer. Grows at 1150 degrees Celsius on 90. The thickness of the n-type AlGaN layer 91 is 2300 nm. The growth rate of the n-type AlGaN layer 91 is 46.0 nm / min. The Al composition of the n-type AlGaN layer 91 is 0.04.

Next, TMG (98.7 μmol / min), NH ₃ (5 slm), and SiH ₄ are supplied to the growth reactor to grow the n-type GaN layer 92 on the n-type AlGaN layer 91 at 1150 degrees Celsius. The n-type GaN layer 92 has a thickness of 50 nm. The growth rate of the n-type GaN layer 92 is 58.0 nm / min. TMG (24.4 μmol / min), TMI (4.6 μmol / min), NH ₃ (6 slm) was supplied to the growth reactor, and an undoped InGaN layer 93a for the light guide layer was formed on the n-type GaN layer 94 in Celsius. Grows at 840 degrees. The n-type InGaN layer 93a has a thickness of 65 nm. The growth rate of the n-type InGaN layer 93a is 6.7 nm / min. The In composition of the undoped InGaN layer 93a is 0.05. Next, an active layer 94 is formed. TMG (15.6 μmol / min), TMI (29.0 μmol / min), and NH 3 (8 slm) are supplied to the growth reactor to grow an undoped InGaN well layer at 745 degrees Celsius. The thickness of the InGaN layer is 3 nm. The growth rate of the InGaN layer is 3.1 nm / min.

Next, while maintaining the temperature of the growth furnace at 745 degrees Celsius, TMG (15.6 μmol / min), TMI (0.3 μmol / min), NH ₃ (8 slm) was supplied to the growth furnace, and the undoped GaN layer was formed. Grows on the InGaN layer at 745 degrees Celsius. The thickness of the GaN layer is 1 nm. The growth rate of the GaN layer is 3.1 nm / min. After growing the undoped GaN layer, the temperature of the growth furnace is changed from 745 degrees Celsius to 870 degrees Celsius. TMG (24.4 μmol / min), TMI (1.6 μmol / min), NH ₃ (6 slm) was supplied to the growth reactor, and an undoped InGaN layer for the barrier layer was formed on the undoped InGaN well layer at 870 degrees Celsius. grow up. The thickness of the InGaN layer is 15 nm. The growth rate of the InGaN layer is 6.7 nm / min. The In composition of the undoped InGaN layer is 0.02.

Next, the temperature of the growth furnace is changed from 870 degrees Celsius to 745 degrees Celsius. Thereafter, TMG (15.6 μmol / min), TMI (29.0 μmol / min), and NH ₃ (8 slm) are supplied to the growth reactor to grow an undoped InGaN well layer on the InGaN layer at 745 degrees Celsius. The thickness of the InGaN layer is 3 nm. The growth rate of the InGaN layer is 3.1 nm / min. The In composition of the undoped InGaN layer is 0.25.

The growth of the well layer and the barrier layer is repeated twice. Thereafter, TMG (13.0 μmol / min), TMI (4.6 μmol / min), and NH ₃ (6 slm) are supplied to the growth reactor, and an undoped InGaN layer 93 b for the light guide layer is formed on the active layer 94. Grows at 840 degrees Celsius. The thickness of the InGaN layer 93b is 65 nm. The growth rate of the InGaN layer 93b is 6.7 nm / min. Next, TMG (98.7 μmol / min) and NH ₃ (5 slm) are supplied to the growth furnace, and the undoped GaN layer 96 is grown on the InGaN layer 93b at 1100 degrees Celsius. The thickness of the GaN layer 96 is 50 nm. The growth rate of the GaN layer 96 is 58.0 nm / min. The In composition of the undoped InGaN layer 93b is 0.05.

Next, TMG (16.6 μmol / min), TMA (2.8 μmol / min), NH ₃ (6 slm), and Cp ₂ Mg are supplied to the growth reactor, and the p-type AlGaN layer 97 is placed on the GaN layer 96 at 1100 Celsius degrees. Grows at a degree. The thickness of the AlGaN layer 97 is 20 nm. The growth rate of the AlGaN layer 97 is 4.9 nm / min. The Al composition of the p-type AlGaN layer 97 is 0.15. TMG (36.6 μmol / min), TMA (3.0 μmol / min), NH ₃ (6 slm), and Cp ₂ Mg are supplied to the growth reactor, and the p-type AlGaN layer 98 is placed on the p-type AlGaN layer 97 at 1100 Celsius degrees. Grows at a degree. The thickness of the AlGaN layer 98 is 400 nm. The composition of Al is 0.06. The growth rate of the AlGaN layer 98 is 13.0 nm / min. Further, TMG (34.1 μmol / min), NH ₃ (5 slm), and Cp ₂ Mg are supplied to the growth reactor, and the p-type GaN layer 99 is grown on the p-type AlGaN layer 98 at 1100 degrees Celsius. The thickness of the GaN layer 99 is 50 nm. The growth rate of the p-type GaN layer 99 is 18.0 nm / min. An epitaxial wafer is manufactured by these steps.

  A ridge structure and an anode AN are formed using this epitaxial wafer, and a cathode CT is formed using the epitaxial wafer to produce a substrate product. After this, the substrate products can be separated to produce individual laser diodes. The anode electrode is electrically connected to the p-type GaN layer via an insulating film 95 having a stripe window with a width of 10 μm provided on the upper surface of the ridge structure, for example. The substrate product is cut to form end faces for the pair of resonators. A laser diode LD0 having a resonator length of 600 micrometers and a ridge width of 2 micrometers is manufactured.

(Example 2)
FIG. 7 is a drawing schematically showing an optical module including a semiconductor laser device mounted on a side surface of a metal pedestal. The semiconductor laser element 11 is mounted on the side surface of the metal pedestal 76 provided on the main surface 10c of the stem 10a. The metal pedestal 76 is made of, for example, copper. In one form of the optical module 71 (referred to as a vertical mounting form in this embodiment), heat from the semiconductor laser element 11 is conducted to the metal base via the metal base 76. The size of the metal base 76 is, for example, 1 mm square. The semiconductor laser element 11 is mounted at a height of 100 to 400 μm on the side surface of the metal pedestal 76. 8A shows the arrangement of the submount 3, the semiconductor laser element 11, and the metal pedestal 76 on the main surface 10c of the stem 10a. The material of the stem is made of iron (Fe), and its thermal conductivity is 71.2 W / (m · K). The diameter of the stem is 5.6 mm, and the thickness of the stem is 1 mm. As a result of the heat conduction simulation of this mounting form, the thermal resistance is 22, 73 ° C./W. Here, the definition of the thermal resistance is defined as the difference between the junction temperature and the stem outer peripheral temperature when 1 W is turned on. Part (b) of FIG. 8 shows the arrangement of the metal pedestals 76a on the main surface 10c of the stem 10a as another example of the mounting form in FIG. As another example, according to the result of the heat conduction simulation of the optical module using the metal base 76a having a size (R = 1.6 mm, “R” is a radius), the thermal resistance is 21, 76 ° C./W.

  However, in the mounting form shown in FIG. 7 (a form in which the semiconductor laser element is mounted on the side surface of the metal pedestal), the shape of the metal pedestal is changed due to restrictions on both the arrangement of the lead terminals and the arrangement of the semiconductor laser element. Improvement by is the limit.

  Referring to FIG. 9A, one form of the mounting member 90 according to the present embodiment (referred to as a horizontal mounting form in this example) is shown. The same stem as described above is used, and the mounting member 90 is made of copper. The semiconductor laser element 11 is mounted on the upper surface of the mounting member 90 via the submount 3. When the thickness of the mounting member 90 is 0.25 mm, the thermal resistance is 20, 54 ° C./W as a result of the thermal conduction simulation of the optical module of this embodiment. When the thickness of the mounting member 90 is 0.50 mm, the thermal resistance is 20, 04 ° C./W as a result of the thermal conduction simulation of the optical module of this embodiment. The thermal conductivity of the mounting member 90 made of copper (Cu) is 398 W / (m · K). The size of the mounting member 90 is a radius of 1.6 mm.

  In the horizontal mounting mode, although the mounting member 90 is thin, as a result of the horizontal mounting of the semiconductor laser element 11, it is possible to relax the restrictions on the arrangement of the semiconductor laser elements without limiting the arrangement of the lead terminals. it can. For this reason, it becomes possible to change the shape of the mounting member 90 significantly.

  Referring to part (b) of FIG. 9, one form of the mounting member 9 according to the present embodiment is shown. The mounting member 90 is made of copper. A semiconductor laser element 11 is mounted on the upper surface of the mounting member 9 via the submount 3. The mounting member 90 is made of copper (Cu), and its thermal conductivity is 398 W / (m · K). The diameter of the mounting member 90 is 3.2 mm. The planar shape of the mounting member 9 is a line-symmetric shape with respect to the reference axes RA1 and RA2.

FIG. 10 shows the relationship between the thickness of the copper heat sink used as the mounting member 9 and the thermal resistance. The thickness of the mounting member 9 was variously changed in the range from zero to 3 mm, and the heat conduction simulation of the optical module was performed. The stem has the same form as described above. The resulting value is shown.
The thickness and thermal resistance of the mounting member 9.
0 mm, 22.5 ° C./W.
0.25 mm, 20.5 ° C./W.
0.50 mm, 20.0 ° C./W.
1.00 mm, 20.1 ° C./W.
2.00 mm, 20.9 ° C./W.
3.00 mm, 21.8 ° C./W.
As a result of the heat conduction simulation, the mounting member 9 has a range of, for example, 0.2 mm or more and 1.6 mm or less.

  The present invention is not limited to the specific configuration disclosed in the present embodiment.

  According to the embodiment of the present invention, there is provided an optical module that can provide good heat dissipation to a semiconductor laser device in a mounting form using a stem.

DESCRIPTION OF SYMBOLS 1,71 ... Optical module, 10a ... Stem, 10b ... Lens cap, 3 ... Submount, 3a ... Main surface, 3c ... Electrode, 9 ... Mounting member, 11 ... Semiconductor laser element, 13 ... Laser structure, 13a ... No. 1 surface, 13b ... second surface, 15 ... electrode, 17 ... substrate, 17a ... main surface, 17b ... back surface, 19 ... semiconductor laminate, 19a ... semiconductor region surface, 21 ... first cladding layer, 23 ... first 2 clad layers, 25 ... active layer, 25 a ... well layer, 25 b ... barrier layer, 27, 29 ... split section, ALPHA ... angle, Sc ... c-plane, NX ... normal axis, 31 ... insulating film, 31 a ... insulating film Opening, 35 ... n-side light guide layer, 37 ... p-side light guide layer, 39 ... carrier block layer, 41 ... electrode, 43a, 43b ... dielectric multilayer film, 75 ... mirror, 77b to 77c ... lead terminal, 79a, 79b ... Bondin Wire.

Claims (20)

An optical module,
An edge emitting semiconductor laser element including an active layer;
A submount having a mounting surface and a back surface for mounting the semiconductor laser element;
A stem including a first lead terminal, a second lead terminal, and a base supporting the first lead terminal and the second lead terminal;
A mounting member having a mounting surface on which the submount is mounted and a fixed surface that joins the main surface of the stem;
With
The mounting member is made of metal, the thermal conductivity of the mounting member is higher than the thermal conductivity of the base, the mounting surface of the mounting member is on the opposite side of the fixed surface of the mounting member, and the mounting The member has a thickness in the range of 0.2 mm to 1.6 mm,
The main surface of the stem is divided by a first reference axis extending in a direction from one of the first lead terminal and the second lead terminal to the other of the first lead terminal and the second lead terminal on the main surface, and a first area Has two areas,
The mounting member extends from the first area to the second area across the first reference axis;
The mounting member includes a first region, a second region, and a third region,
The first region, the second region, and the third region are sequentially arranged in an extending direction of a second reference axis that extends in a direction intersecting the first reference axis on the main surface of the stem. And
The optical module further includes an optical component that reflects a laser beam emitted from the semiconductor laser element and changes a traveling direction of the laser beam, and the optical component is on the mounting surface in the second region of the mounting member. The semiconductor laser element is located on the mounting surface of the mounting member via the submount,
The first region includes a portion having a width greater than that of the second region;
The optical module, wherein the third region includes a portion having a width greater than or equal to the width of the second region.   The optical module according to claim 1, wherein the active layer of the semiconductor laser element is made of a group III nitride semiconductor. The semiconductor laser element includes an n-type group III nitride semiconductor region provided on a substrate, and a p-type group III nitride semiconductor region provided on the substrate,
The active layer is provided between the n-type group III nitride semiconductor region and the p-type group III nitride semiconductor region,
The optical module according to claim 1, wherein the active layer is provided so that an oscillation wavelength of the semiconductor laser element is 400 nm or more and 550 nm or less.   4. The optical module according to claim 1, wherein an oscillation wavelength of the semiconductor laser element is in a range of not less than 480 nm and not more than 540 nm.   5. The optical module according to claim 1, wherein an oscillation wavelength of the semiconductor laser element is in a range from 510 nm to 540 nm. The semiconductor laser element has a light guide layer,
The light guide layer is made of a hexagonal gallium nitride semiconductor,
The light guide layer is in contact with the active layer;
The interface between the active layer and the light guide layer is orthogonal to the cm plane defined by the c-axis of the gallium nitride semiconductor and the m-axis of the gallium nitride semiconductor;
The interface between the active layer and the light guide layer is the c-axis in the direction from the c-axis vector indicating the c-axis direction to the m-axis vector indicating the m-axis direction on the cm plane. The optical module according to any one of claims 1 to 5, wherein the optical module is inclined at an angle ALPHA from a reference plane orthogonal to.   The optical module according to claim 6, wherein the angle ALPHA is in a range of not less than 63 degrees and less than 80 degrees.   The optical module according to claim 1, wherein the mounting member includes any one of copper and an alloy containing copper.   The optical module according to claim 1, wherein the mounting member includes any one of copper tungsten and copper molybdenum.   The optical module according to claim 1, wherein the semiconductor laser element is mounted on the main surface of the submount in an epi-down form. A cap provided on the stem and having an optical window;
The stem and the cap provide a cavity for accommodating the semiconductor laser element, the submount and the mounting member,
The thermal conductivity of the mounting member is greater than the thermal conductivity of the submount,
11. The optical module according to claim 1, wherein the semiconductor laser element is optically coupled to the optical window of the cap via the optical component.   The optical module according to claim 1, wherein the optical component includes a mirror for reflecting laser light emitted from the semiconductor laser element. The semiconductor laser element has a waveguide structure including the active layer and a substrate,
13. The optical module according to claim 1, wherein the semiconductor laser element has the waveguide structure extending on a main surface of the substrate. A width of the mounting member has a first value on the first reference axis;
The mounting member has a portion in which the width of the mounting member monotonously changes as the distance from the first reference axis increases from the point on the first reference axis in the extending direction of the second reference axis;
14. The optical module according to claim 1, wherein a maximum width of the portion of the mounting member is larger than the first value. The base of the stem has a first opening penetrating from the back surface of the stem to the main surface of the stem;
The first lead terminal is supported by the base of the stem through a sealing material in the first opening,
The optical module according to claim 1, wherein a side surface of the mounting member includes a curved surface extending away from an edge of the first opening. The main surface of the stem has an edge of a convex curve;
16. The light according to claim 1, wherein a side surface of the mounting member has a convex curved surface extending to the first area away from the edge of the main surface of the stem. module. The base of the stem has a second opening penetrating from the back surface of the stem to the main surface of the stem;
The second lead terminal is supported by the base of the stem through a sealing material in the second opening,
The main surface of the stem has a curved edge,
The side surface of the mounting member has a first curved surface extending in the second area away from the edge of the second opening, and a second curved surface extending in the second area away from the edge of the main surface of the stem. The optical module according to claim 1, which has two curved surfaces. The first lead terminal and the second lead terminal respectively have the first lead terminal portion and the second lead terminal portion protruding from the upper surface of the base,
The mounting member includes a first part joining the submount, and a second part adjacent to the first part,
18. The optical module according to claim 1, wherein a thickness of the first portion of the mounting member is smaller than a height of the first lead terminal portion.   The mounting member includes a first recess and a second recess provided in the direction of the first reference axis on the main surface of the stem, and a direction of the second reference axis on the main surface of the stem. The optical module as described in any one of Claims 1-18 including the 1st convex part and 2nd convex part which were provided in.   The optical module according to any one of claims 1 to 19, wherein the mounting member is made of a metal plate.

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