JP2018085450A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module capable of synthesizing light from a plurality of semiconductor laser elements of the same color to output the resultant light while ensuring an adequate heat dissipation property.SOLUTION: An optical module 1 comprises: a base member 60; a first semiconductor laser element 51 including a first semiconductor laminate; a second semiconductor laser element 52 including a second semiconductor laminate; and a polarization synthesis filter 87 operable to synthesize light from the first semiconductor laser element 51 and light from the second semiconductor laser element 52. The difference in wavelength between the light from the first semiconductor laser element 51 and the light from the second semiconductor laser element 52 is 30 nm or less. An angle formed by a laminating direction of the first semiconductor laminate and a laminating direction of the second semiconductor laminate is 10° or less. An angle formed by a polarization direction of light from the first semiconductor laser element 51, entering the polarization synthesis filter 87, and a polarization direction of light from the second semiconductor laser element 52 is 80° or more and 100° or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical module.

  An optical module in which a semiconductor laser element is arranged in a package is known (see, for example, Patent Documents 1 to 4). Such an optical module is used as a light source of various devices such as a display device, an optical pickup device, and an optical communication device.

JP 2009-93101 A JP 2007-328895 A JP 2007-17925 A JP 2007-65600 A

  In the optical module, an increase in light intensity may be required for a specific color. However, there is a limit to the increase in light intensity simply by increasing the input power to the semiconductor laser element that emits light of a specific color. Therefore, for example, it is effective to increase the intensity of light by combining light from a plurality of semiconductor laser elements of the same color (specifically, the difference in wavelength of emitted light is 30 nm or less).

  Specifically, for example, two semiconductor laser elements of the same color are placed on wall surfaces that are perpendicular to each other (or close to vertical) so that the polarization directions are perpendicular to each other (or close to vertical), and the two semiconductor lasers Light from the element can be incident on the polarization beam combining filter and multiplexed. However, when an arrangement in which two semiconductor laser elements are installed on wall surfaces that are perpendicular (or nearly perpendicular) to each other is adopted, the heat dissipation of one of the two semiconductor laser elements decreases, and the one There arises a problem that the output of the semiconductor laser element decreases.

  Accordingly, an object is to provide an optical module that can combine and emit light from a plurality of semiconductor laser elements of the same color while ensuring sufficient heat dissipation.

  An optical module according to the present invention includes a base member, a first semiconductor laser element disposed on the base member and including the first semiconductor multilayer body, and a second semiconductor layer disposed on the base member and including the second semiconductor multilayer body. A semiconductor laser element; and a polarization beam combining filter disposed on the base member and configured to multiplex the light from the first semiconductor laser element and the light from the second semiconductor laser element. The difference between the wavelength of light from the first semiconductor laser element and the wavelength of light from the second semiconductor laser element is 30 nm or less. The angle formed by the stacking direction of the first semiconductor stacked body and the stacking direction of the second semiconductor stacked body is 10 ° or less. The angle formed by the polarization direction of the light from the first semiconductor laser element incident on the polarization beam combining filter and the polarization direction of the light from the second semiconductor laser element is 80 ° or more and 100 ° or less.

  According to the above optical module, it is possible to provide an optical module capable of combining and emitting light from a plurality of semiconductor laser elements of the same color while ensuring sufficient heat dissipation.

It is a schematic perspective view which shows the structure of an optical module. It is a schematic perspective view which shows the structure of an optical module. It is a schematic plan view which shows the structure of an optical module. It is a schematic sectional drawing which shows an example of the structure of a red laser diode. It is a schematic sectional drawing corresponding to the state which looked at the cross section in alignment with the line segment VV of FIG. 3 in the direction of the arrow.

[Description of Embodiment of Present Invention]
First, embodiments of the present invention will be listed and described. An optical module of the present application includes a base member, a first semiconductor laser element disposed on the base member and including a first semiconductor multilayer body, and a second semiconductor laser element disposed on the base member and including a second semiconductor multilayer body And a polarization combining filter that is disposed on the base member and multiplexes the light from the first semiconductor laser element and the light from the second semiconductor laser element. The difference between the wavelength of light from the first semiconductor laser element and the wavelength of light from the second semiconductor laser element is 30 nm or less. The angle formed by the stacking direction of the first semiconductor stacked body and the stacking direction of the second semiconductor stacked body is 10 ° or less. The angle formed by the polarization direction of the light from the first semiconductor laser element incident on the polarization beam combining filter and the polarization direction of the light from the second semiconductor laser element is 80 ° or more and 100 ° or less.

  The optical module of the present application has a structure in which the light from the first semiconductor laser element and the light from the second semiconductor laser element of the same color (the difference in wavelength of emitted light is 30 nm or less) are combined in the polarization combining filter Have Here, the angle formed by the stacking direction of the first semiconductor stacked body and the stacking direction of the second semiconductor stacked body is 10 ° or less. That is, the first semiconductor laser element and the second semiconductor laser element are not installed perpendicular to each other, but are installed in a parallel or nearly parallel state. Therefore, it is easy to ensure sufficient heat dissipation of the first semiconductor laser element and the second semiconductor laser element.

  The angle between the polarization direction of the light from the first semiconductor laser element incident on the polarization beam combining filter and the polarization direction of the light from the second semiconductor laser element is 80 ° or more and 100 ° or less. That is, the polarization direction of the light from the first semiconductor laser element incident on the polarization beam combining filter and the polarization direction of the light from the second semiconductor laser element are vertical or nearly perpendicular. As a result, the light from the first semiconductor laser element and the light from the second semiconductor laser element are combined in the polarization combining filter. That is, in the optical module of the present application, the first semiconductor laser element and the second semiconductor laser element that emit outgoing light whose polarization directions with respect to the stacking direction of the semiconductor stacked body are perpendicular or nearly perpendicular to each other are employed. For this reason, the first and second semiconductor laser elements can be combined with the polarization combining filter in a state where the first semiconductor laser element and the second semiconductor laser element are installed in parallel or nearly parallel to each other.

  Thus, according to the optical module of the present application, it is possible to provide an optical module capable of combining and emitting light from a plurality of semiconductor laser elements of the same color while ensuring sufficient heat dissipation. .

  The optical module has an emission window that transmits light from the first semiconductor laser element and light from the second semiconductor laser element, and includes a base member, a first semiconductor laser element, a second semiconductor laser element, and a polarization combining filter. May further be provided. As described above, the structure in which the base member, the first semiconductor laser element, the second semiconductor laser element, and the polarization wave synthesis filter are arranged in one package can facilitate the handling of the optical module.

  In the optical module, the first semiconductor laser element and the second semiconductor laser element may be red semiconductor laser elements that emit red light. The red semiconductor laser device can easily control the polarization direction of the emitted light with respect to the stacking direction of the semiconductor stacked body. Therefore, the red semiconductor laser element is suitable as the first semiconductor laser element and the second semiconductor laser element of the optical module of the present application.

  The optical module is disposed on the base member, and is disposed on the base member, a third semiconductor laser element that emits green light, a fourth semiconductor laser element that is disposed on the base member and emits blue light, and the base member. A multiplexing filter that multiplexes the light from the first semiconductor laser element and the second semiconductor laser element, which are red semiconductor laser elements, and the light from the third semiconductor laser element and the light from the fourth semiconductor laser element. Furthermore, you may provide. By doing so, it becomes easy to form light of a desired color.

[Details of the embodiment of the present invention]
Next, an embodiment of an optical module according to the present invention will be described with reference to FIGS. FIG. 2 is a view corresponding to a state in which the cap 40 of FIG. 1 is removed. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  Referring to FIGS. 1 and 2, an optical module 1 in the present embodiment includes a stem 10 having a flat plate shape, and a light forming portion that is disposed on one main surface 10A of the stem 10 to form light. 20, a cap 40 disposed in contact with one main surface 10 </ b> A of the stem 10 so as to cover the light forming portion 20, and the other main surface 10 </ b> B side of the stem 10 to the one main surface 10 </ b> A side. And a plurality of lead pins 45 projecting on both sides of one main surface 10A side and the other main surface 10B side. The stem 10 and the cap 40 are in an airtight state by welding, for example. That is, the light forming unit 20 is hermetically sealed by the stem 10 and the cap 40. A space surrounded by the stem 10 and the cap 40 is filled with a gas in which moisture is reduced (removed) such as dry air. The cap 40 is formed with an emission window 41 that transmits light from the light forming unit 20. The exit window 41 may have a flat plate shape whose main surfaces are parallel to each other, or may have a lens shape that collects or diffuses the light from the light forming unit 20. The stem 10 and the cap 40 constitute a protective member.

  Referring to FIGS. 2 and 3, light forming unit 20 includes a base plate 60 that is a base member having a plate shape. The base plate 60 has a rectangular planar shape. Four semiconductor laser elements are arranged along a region corresponding to one long side of the mounting surface 60 </ b> A that is one surface of the base plate 60.

  Specifically, the first chip mounting area 61 is arranged in an area corresponding to one end of one long side on the mounting surface 60A. The first chip mounting area 61 is a rectangular parallelepiped area in which the thickness of the base plate 60 is larger than the surrounding area. As a result, the height of the first chip mounting area 61 is higher than the surrounding area. On the first chip mounting region 61, a flat plate-like first submount 71 is disposed. A first red laser diode 51, which is a first semiconductor laser element, is disposed on the first submount 71.

  A first photodiode 91 as a first light receiving element is disposed in a region adjacent to the emission direction of the first red laser diode 51 as viewed from the first chip mounting region 61 of the base plate 60. The first photodiode 91 has a light receiving surface 91A.

  In a region corresponding to one long side of one main surface of the base plate 60, a second chip mounting region 62 is disposed on the mounting surface 60A adjacent to the first chip mounting region 61. The second chip mounting area 62 is a rectangular parallelepiped area in which the thickness of the base plate 60 is larger than the surrounding area. As a result, the height of the second chip mounting area 62 is higher than the surrounding area. On the second chip mounting area 62, a flat plate-like second submount 72 is arranged. A second red laser diode 52, which is a second semiconductor laser element, is disposed on the second submount 72.

  The difference in oscillation wavelength between the first red laser diode 51 and the second red laser diode 52 is 30 nm or less, and may be 10 nm or less. Each of the first red laser diode 51 and the second red laser diode 52 emits red light (laser light).

  In a region adjacent to the emission direction of the second red laser diode 52 when viewed from the second chip mounting region 62 of the base plate 60, a second photodiode 92 as a second light receiving element is disposed. The second photodiode 92 has a light receiving surface 92A.

  In a region corresponding to one long side of one main surface (mounting surface 60A) of the base plate 60, the third chip mounting region is located on the side opposite to the first chip mounting region 61 when viewed from the second chip mounting region 62. 63 is arranged. The third chip mounting area 63 is a rectangular parallelepiped area in which the thickness of the base plate 60 is larger than the surrounding area. As a result, the height of the third chip mounting area 63 is higher than the surrounding area. On the third chip mounting area 63, a flat plate-like third submount 73 is arranged. A green laser diode 53 that is a third semiconductor laser element is disposed on the third submount 73.

  A third photodiode 93 as a third light receiving element is disposed in a region adjacent to the emission direction of the green laser diode 53 as viewed from the third chip mounting region 63 of the base plate 60. The third photodiode 93 has a light receiving surface 93A.

  In a region corresponding to one long side of one main surface (mounting surface 60 </ b> A) of the base plate 60, a fourth chip mounting region is located on the side opposite to the second chip mounting region 62 when viewed from the third chip mounting region 63. 64 is arranged. The fourth chip mounting area 64 is disposed in an area corresponding to the other end of the one long side. The fourth chip mounting area 64 is a rectangular parallelepiped area in which the thickness of the base plate 60 is larger than the surrounding area. As a result, the height of the fourth chip mounting area 64 is higher than the surrounding area. On the fourth chip mounting area 64, a flat plate-like fourth submount 74 is arranged. A blue laser diode 54 that is a fourth semiconductor laser element is disposed on the fourth submount 74.

  In a region adjacent to the emission direction of the blue laser diode 54 when viewed from the fourth chip mounting region 64 of the base plate 60, a fourth photodiode 94 as a fourth light receiving element is disposed. The fourth photodiode 94 has a light receiving surface 94A.

  The first photodiode 91, the second photodiode 92, the third photodiode 93, and the fourth photodiode 94 are respectively from the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and the blue laser diode 54. It is installed at a position to directly receive the light. In the present embodiment, light receiving elements are arranged corresponding to all the laser elements. The first photodiode 91 and the second photodiode 92 are photodiodes that can receive red light. The third photodiode 93 is a photodiode that can receive green light. The fourth photodiode 94 is a photodiode capable of receiving blue light.

  The first photodiode 91 is disposed between the first red laser diode 51 and the first lens 81 in the emission direction of the first red laser diode 51. The second photodiode 92 is disposed between the second red laser diode 52 and the second lens 82 in the emission direction of the second red laser diode 52. The third photodiode 93 is disposed between the green laser diode 53 and the third lens 83 in the emission direction of the green laser diode 53. The fourth photodiode 94 is disposed between the blue laser diode 54 and the fourth lens 84 in the emission direction of the blue laser diode 54.

  On the base plate 60 opposite to the first red laser diode 51 as viewed from the first photodiode 91, a flat plate-like first lens support portion 81B is disposed. And the 1st lens 81 is arrange | positioned on the 1st lens support part 81B. On the base plate 60 opposite to the second red laser diode 52 when viewed from the second photodiode 92, a flat plate-like second lens support portion 82B is disposed. A second lens 82 is disposed on the second lens support portion 82B. On the base plate 60 opposite to the green laser diode 53 when viewed from the third photodiode 93, a flat plate-like third lens support portion 83B is disposed. The third lens 83 is disposed on the third lens support portion 83B. On the base plate 60 opposite to the blue laser diode 54 when viewed from the fourth photodiode 94, a flat plate-like fourth lens support portion 84B is disposed. And the 4th lens 84 is arrange | positioned on the 4th lens support part 84B.

  The first lens 81, the second lens 82, the third lens 83, and the fourth lens 84 each have a lens portion 81A, a lens portion 82A, a lens portion 83A, and a lens portion 84A, which are portions whose surfaces are lens surfaces. doing. In the first lens 81, the second lens 82, the third lens 83, and the fourth lens 84, the lens portions 81A, 82A, 83A, and 84A and regions other than the lens portions 81A, 82A, 83A, and 84A are integrally molded. . The first lens 81, the second lens 82, the third lens 83, and the fourth lens 84 are formed by the first lens support portion 81B, the second lens support portion 82B, the third lens support portion 83B, and the fourth lens support portion 84B. The central axes of the portions 81A, 82A, 83A, 84A, that is, the optical axes of the lens portions 81A, 82A, 83A, 84A are the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and the blue laser diode, respectively. It is adjusted to coincide with 54 optical axes. The first lens 81, the second lens 82, the third lens 83, and the fourth lens 84 are emitted from the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and the blue laser diode 54, respectively. Convert spot size. By the first lens 81, the second lens 82, the third lens 83, and the fourth lens 84, the light emitted from the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and the blue laser diode 54 The spot size is converted so that the spot sizes match.

  On the base plate 60 opposite to the first red laser diode 51 when viewed from the first lens 81, a flat plate-like first filter support portion 86B is disposed. And the 1st filter 86 is arrange | positioned on the 1st filter support part 86B. The first filter 86 is a wavelength selective filter. The first filter 86 reflects red light.

  On the base plate 60 opposite to the second red laser diode 52 when viewed from the second lens 82, a flat plate-like second filter support portion 87B is disposed. And the 2nd filter 87 is arrange | positioned on the 2nd filter support part 87B. The second filter 87 is a red polarization synthesis filter.

  On the base plate 60 opposite to the green laser diode 53 when viewed from the third lens 83, a flat plate-like third filter support portion 88B is disposed. And the 3rd filter 88 is arrange | positioned on the 3rd filter support part 88B. The third filter 88 is a wavelength selective filter. The third filter 88 transmits red light and reflects green light.

  On the base plate 60 opposite to the blue laser diode 54 when viewed from the fourth lens 84, a flat plate-like fourth filter support portion 89B is disposed. And the 4th filter 89 is arrange | positioned on the 4th filter support part 89B. The fourth filter 89 is a wavelength selective filter. The fourth filter 89 transmits red light and green light, and reflects blue light.

  The first filter 86, the second filter 87, the third filter 88, and the fourth filter 89 each have a flat plate shape having main surfaces parallel to each other.

  Referring to FIG. 3, the first red laser diode 51, the first photodiode 91, the first lens 81, and the first filter 86 are in a direction along the light emission direction of the first red laser diode 51 (Y-axis direction). Are arranged side by side. The second red laser diode 52, the second photodiode 92, the second lens 82, and the second filter 87 are arranged side by side in the direction (Y-axis direction) along the light emission direction of the second red laser diode 52. . The green laser diode 53, the third photodiode 93, the third lens 83, and the third filter 88 are arranged side by side in the direction (Y-axis direction) along the light emission direction of the green laser diode 53. The blue laser diode 54, the fourth photodiode 94, the fourth lens 84, and the fourth filter 89 are arranged side by side in the direction (Y-axis direction) along the light emission direction of the blue laser diode 54.

  The first filter 86, the second filter 87, the third filter 88, and the fourth filter 89 are light emission directions from the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and the blue laser diode 54. Are arranged side by side along a direction that intersects, more specifically, an orthogonal direction (X-axis direction). The main surfaces of the first filter 86, the second filter 87, the third filter 88, and the fourth filter 89 are respectively from the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and the blue laser diode 54. It is inclined with respect to the light emitting direction. More specifically, the main surfaces of the first filter 86, the second filter 87, the third filter 88, and the fourth filter 89 are the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and It is inclined by 45 ° with respect to the light emission direction (Y-axis direction) from the blue laser diode 54.

  Referring to FIG. 2, the optical module 1 of the present embodiment further includes an electronic cooling module 30 between the stem 10 and the light forming unit 20. The electronic cooling module 30 includes a heat absorbing plate (not shown), a heat radiating plate 32, and a semiconductor pillar 33 arranged side by side between the heat absorbing plate and the heat radiating plate 32 with electrodes interposed therebetween. The heat absorbing plate and the heat radiating plate 32 are made of alumina, for example. The heat absorbing plate is disposed in contact with the other main surface 60B of the base plate 60. The heat radiating plate 32 is disposed in contact with one main surface 10 </ b> A of the stem 10. In the present embodiment, the electronic cooling module 30 is a Peltier module (Peltier element). Then, by passing an electric current through the electronic cooling module 30, the heat of the base plate 60 that contacts the heat absorbing plate moves to the stem 10, and the base plate 60 is cooled. As a result, the temperature increase of the first red laser diode 51, the second red laser diode 52, the green laser diode 53, and the blue laser diode 54 is suppressed. Thus, by maintaining the temperature of the laser diode in an appropriate range, it is possible to accurately form light of a desired color.

  2 and 3, islands 105 to 107 are arranged between adjacent lenses 81 to 84 and filters 86 to 89 on mounting surface 60 </ b> A of base plate 60. More specifically, recesses are formed on the mounting surface 60A of the base plate 60 so as to extend from between the adjacent lenses 81 to 84 to between the filters 86 to 89, and are located within the recesses. In addition, islands 105 to 107 are arranged. The islands 105 to 107 have a structure in which a metal as a conductor is deposited on the surface of a base body made of, for example, an insulator.

  Next, the structure of the first red laser diode 51 and the second red laser diode 52 (red laser diode 200) of the present embodiment will be described.

  FIG. 4 is a schematic cross-sectional view showing an example of the structure of the red laser diode 200. FIG. 4 corresponds to a cross section perpendicular to the direction in which light repeatedly reflects on the end face in the active layer 123 (hereinafter referred to as “end face reflection direction”). Referring to FIG. 4, red laser diode 200 in the present embodiment includes substrate 110, semiconductor layer 120, p-side electrode 141, and n-side electrode 142. The substrate 110 and the semiconductor layer 120 constitute a semiconductor stacked body. The substrate 110 is made of, for example, GaAs (gallium arsenide). The conductivity type of the substrate 110 is n-type. The substrate 110 has a first main surface 110A and a second main surface 110B that is a main surface opposite to the first main surface 110A.

  The semiconductor layer 120 is disposed so as to be in contact with the first main surface 110 </ b> A of the substrate 110. The semiconductor layer 120 is a layer formed by epitaxial growth on the first main surface 110 </ b> A of the substrate 110. The semiconductor layer 120 is made of a group III-V nitride semiconductor. The semiconductor layer 120 includes a buffer layer 121, an n-side cladding layer 122, an active layer 123, a p-side cladding layer 124, a current blocking layer 125, a p-type layer 126, and a cap layer 127. .

The buffer layer 121 is disposed so as to be in contact with the first main surface 110A of the substrate 110. The buffer layer 121 is made of, for example, Ga _0.5 In _0.5 P (gallium indium phosphide) whose conductivity type is n-type. The buffer layer 121 is a layer formed by epitaxial growth on the first main surface 110 </ b> A of the substrate 110.

The n-side cladding layer 122 is disposed so as to be in contact with the main surface 121A on the opposite side of the buffer layer 121 from the substrate 110. The n-side cladding layer 122 is made of, for example, n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P (aluminum gallium indium phosphide). The n-side cladding layer 122 is a layer formed by epitaxial growth on the main surface 121 </ b> A of the buffer layer 121.

The active layer 123 is disposed so as to be in contact with the main surface 122A of the n-side cladding layer 122 opposite to the buffer layer 121. The active layer 123 is, for example, an MQW (Multiple Quantum Well) layer having a structure in which well layers made of GaInP and barrier layers made of (Ga _x Al _1-x ) _y In _1-y P are alternately stacked. The active layer 123 is a layer formed by epitaxial growth on the main surface 122A of the n-side cladding layer 122. The active layer 123 generates light by recombination of electrons and holes therein. The active layer 123 generates red light.

The p-side cladding layer 124 is disposed so as to be in contact with the main surface 123A of the active layer 123 opposite to the n-side cladding layer 122. The p-side cladding layer 124 is made of, for example, (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P having a p-type conductivity. The p-side cladding layer 124 is a layer formed by epitaxial growth on the main surface 123A of the active layer 123. The p-side cladding layer 124 has a ridge portion 124B that protrudes on the opposite side of the active layer 123 and extends in the end face reflection direction (direction perpendicular to the paper surface).

  The p-type layer 126 is disposed so as to be in contact with the ridge portion 124 </ b> B of the main surface 124 </ b> A opposite to the active layer 123 of the p-side cladding layer 124. The p-type layer 126 is made of, for example, GaAs whose conductivity type is p-type. The p-type layer 126 is a layer formed on the main surface 124A of the p-side cladding layer 124 by epitaxial growth.

  The current blocking layer 125 is disposed so as to be in contact with the main surface 124A of the p-side cladding layer 124 on the side opposite to the active layer 123. The current blocking layer 125 is made of GaAs whose conductivity type is n-type, for example. The current blocking layer 125 is a layer formed by epitaxial growth on the main surface 124A of the p-side cladding layer 124. The current blocking layer 125 has an opening 125B extending along the ridge portion 124B on the top surface of the ridge portion 124B. The p-type layer 126 is exposed from the opening 125B.

  Cap layer 127 is arranged to cover main surface 125 </ b> A and main surface 126 </ b> A opposite to p-side cladding layer 124 of current blocking layer 125 and p-type layer 126. The cap layer 127 is made of GaAs whose conductivity type is p-type, for example. Cap layer 127 is a layer formed by epitaxial growth on main surface 125 </ b> A and main surface 126 </ b> A of current blocking layer 125 and p-type layer 126.

  The p-side electrode 141 is disposed on the main surface 127A of the cap layer 127 opposite to the current blocking layer 125 and the p-type layer 126. The p-side electrode 141 is made of a conductor such as metal that can form an ohmic contact with the cap layer 127, such as Au (gold).

  On the other hand, the n-side electrode 142 is disposed so as to be in contact with the second main surface 110B of the substrate 110. The n-side electrode 142 is made of a conductor such as a metal that can be in ohmic contact with the substrate 110, such as Au. The n-side electrode 142 and the substrate 110 form an ohmic contact.

  When a voltage is applied between the p-side electrode 141 and the n-side electrode 142, a current flows between the p-side electrode 141 and the n-side electrode 142. At this time, holes are injected from the p-side electrode 141 side and electrons are injected from the n-side electrode 142 side into the active layer 123 constituting the MQW. Then, in the active layer 123, holes and electrons are recombined to generate light. The generated light is confined in the thickness direction of the active layer 123 in the active layer 123 sandwiched between the n-side cladding layer 122 and the p-side cladding layer 124. The confined light is repeatedly reflected in the end surface reflection direction (direction perpendicular to the paper surface). As a result, light with the same phase is amplified and laser oscillation is achieved. And a red laser beam is radiate | emitted from one end surface.

  Here, for example, in the active layer 123, if the value of y is 0.49, the laser light oscillates in a TE (Transverse Electric) mode. On the other hand, in the active layer 123, for example, when the value of y is 0.51, the laser light oscillates in a TM (Transverse Magnetic) mode. In the present embodiment, one of the first red laser diode 51 and the second red laser diode 52 that emits laser light in the TE mode is adopted, and the other emits laser light in the TM mode. Things are adopted.

Next, the arrangement of the first red laser diode 51 and the second red laser diode 52 will be described. FIG. 5 is a schematic cross-sectional view corresponding to a state in which a cross section taken along line VV in FIG. 3 is viewed in the direction of the arrow. 4 and 5, the stacking direction α ₁ of the first semiconductor stack included in the first red laser diode 51 and the stack direction α ₂ of the second semiconductor stack included in the second red laser diode 52 are referred to. the following angle is 10 ° and is first red laser diode 51 and the second red laser diode 52 so as preferably to be parallel and the alpha ₁ and alpha ₂ are arranged. On the other hand, as described above, in the present embodiment, one of the first red laser diode 51 and the second red laser diode 52 emits light in the TE mode, and the other emits light in the TM mode. For example, the first red laser diode 51 emits light whose polarization direction is a direction perpendicular to α ₁ . Second red laser diode 52, polarization direction is emitted light is a direction parallel to the alpha _2.

Next, the operation of the optical module 1 in the present embodiment will be described. Referring to FIG. 3, the red light emitted from the first red laser diode 51 travels along the optical path L _1. At this time, part of the red light directly enters the light receiving surface 91 </ b> A of the first photodiode 91. Thereby, the intensity of the red light emitted from the first red laser diode 51 is grasped, and the first red laser diode 51 is changed based on the difference between the grasped light intensity and the target light intensity to be emitted. The supplied power is adjusted. The red light that has passed over the first photodiode 91 enters the lens portion 81A of the first lens 81, and the spot size of the light is converted. Specifically, for example, red light emitted from the first red laser diode 51 is converted into collimated light. The red light whose spot size has been converted in the first lens 81 travels along the optical path L ₁ and enters the first filter 86. The first filter 86 is a wavelength selective filter that reflects red light. Therefore, the light emitted from the first red laser diode 51 travels along the optical path L ₂ is reflected at the first filter 86. The light emitted from the first red laser diode 51 passes through the second filter 87, the third filter 88, and the fourth filter 89 and further travels along the optical path L ₃ , the optical path L ₄ and the optical path L _5. Then, the light is emitted to the outside of the optical module 1 through the emission window 41 of the cap 40.

Red light emitted from the second red laser diode 52 travels along the optical path L _6. At this time, part of the red light is directly incident on the light receiving surface 92A of the second photodiode 92. Thus, the intensity of the red light emitted from the second red laser diode 52 is grasped, and the second red laser diode 52 is determined based on the difference between the grasped light intensity and the target light intensity to be emitted. The supplied power is adjusted. The red light that has passed over the second photodiode 92 enters the lens portion 82A of the second lens 82, and the spot size of the light is converted. Specifically, for example, red light emitted from the second red laser diode 52 is converted into collimated light. The red light whose spot size has been converted in the second lens 82 travels along the optical path L ₆ and enters the second filter 87. The second filter 87 transmits the red light having a vibration direction in the horizontal direction (direction in the XY plane) and reflects the light having the vibration direction in the vertical direction (Z-axis direction). It is a synthesis filter.

Here, as described with reference to FIG. 4, the first red laser diode 51 emits light whose polarization direction is perpendicular to α ₁ . On the other hand, the second red laser diode 52, polarization direction is emitted light is a direction parallel to the alpha _2. Therefore, the angle formed by the polarization direction of the light from the first red laser diode 51 incident on the second filter 87 and the polarization direction of the light from the second red laser diode 52 is 80 ° to 100 °, preferably Is 90 °.

That is, the vibration direction of the light from the first red laser diode 51 is the direction in the XY plane, and the vibration direction of the light from the second red laser diode 52 is the Z-axis direction. Therefore, the light emitted from the second red laser diode 52 merges is reflected at the second filter 87 in the optical path L _3. As a result, the red light from the second red laser diode 52 is red light and combined from the first red laser diode 51 travels along the optical path L _3. The light emitted from the second red laser diode 52 further proceeds along the optical path L ₄ and the optical path L ₅ is transmitted through the third filter 88 and fourth filter 89, through the exit window 41 of the cap 40 To the outside of the optical module 1.

Green light emitted from the green laser diode 53 travels along the optical path L _7. At this time, part of the green light directly enters the light receiving surface 93A of the third photodiode 93. Thereby, the intensity of the green light emitted from the green laser diode 53 is grasped, and the electric power supplied to the green laser diode 53 based on the difference between the grasped light intensity and the target light intensity to be emitted. Is adjusted. The green light that has passed over the third photodiode 93 is incident on the lens portion 83A of the third lens 83, and the spot size of the light is converted. Specifically, for example, green light emitted from the green laser diode 53 is converted into collimated light. The green light whose spot size has been converted by the third lens 83 travels along the optical path L ₇ and enters the third filter 88. The third filter 88 is a wavelength selective filter (multiplexing filter) that transmits red light and reflects green light. Therefore, light emitted from the green laser diode 53 is reflected in the third filter 88 and joins the optical path L _4. As a result, green light from the green laser diode 53 is red light and combined from the red light and the second red laser diode 52 from the first red laser diode 51 travels along the optical path L ₄ . The light emitted from the green laser diode 53 is transmitted through the fourth filter 89 further proceeds along the optical path L _5, through the exit window 41 of the cap 40 is emitted to the outside of the optical module 1.

Blue light emitted from the blue laser diode 54 travels along the optical path L _8. At this time, part of the blue light is directly incident on the light receiving surface 94A of the fourth photodiode 94. Thereby, the intensity of the blue light emitted from the blue laser diode 54 is grasped, and the electric power supplied to the blue laser diode 54 based on the difference between the grasped light intensity and the target light intensity to be emitted. Is adjusted. The blue light that has passed over the fourth photodiode 94 enters the lens portion 84A of the fourth lens 84, and the spot size of the light is converted. Specifically, for example, blue light emitted from the blue laser diode 54 is converted into collimated light. The blue light whose spot size has been converted by the fourth lens 84 travels along the optical path L ₈ and enters the fourth filter 89. The fourth filter 89 is a wavelength selective filter (multiplexing filter) that transmits red light and green light and reflects blue light. Therefore, light emitted from the blue laser diode 54 joins the optical path L ₅ is reflected in the fourth filter 89. As a result, the blue light from the blue laser diode 54 is combined with the red light from the first red laser diode 51, the red light from the second red laser diode 52, and the green light from the green laser diode 53. Then, the light travels along the optical path L ₅ and exits to the outside of the optical module 1 through the exit window 41 of the cap 40.

In this manner, the light formed by combining the red, green, and blue light is emitted from the emission window 41 of the cap 40. Here, in this embodiment, the stacking direction alpha ₁ of the first semiconductor multilayer body included in the first red laser diode 51, to the stacking direction alpha ₂ of second semiconductor multilayer body included in the second red laser diode 52 The first red laser diode 51 and the second red laser diode 52 are arranged so that the angle formed by the above becomes 10 ° or less. Therefore, it is easy to ensure sufficient heat dissipation of the first red laser diode 51 and the second red laser diode 52. That is, by mounting one of the first red laser diode 51 and the second red laser diode 52 on, for example, the side surface of the block disposed on the base plate 60, it is possible to avoid deteriorating the heat dissipation of the one. it can.

  The angle formed by the polarization direction of the light from the first red laser diode 51 and the polarization direction of the light from the second red laser diode 52 incident on the second filter 87 that is a polarization combining filter is 80 ° or more. One of the first red laser diode 51 and the second red laser diode 52 that emits laser light in the TE mode is employed so that the laser beam is emitted in the TM mode. Things are adopted. Therefore, multiplexing by the second filter 87 is possible in a state where the first red laser diode 51 and the second red laser diode 52 are installed in a state of being parallel or nearly parallel to each other.

  As described above, the optical module 1 of the present embodiment is an optical module capable of combining and emitting light from a plurality of semiconductor laser elements of the same color while ensuring sufficient heat dissipation. .

  It should be understood that the embodiments disclosed herein are illustrative in all respects and are not restrictive in any aspect. The scope of the present invention is defined by the scope of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

  The optical module of the present application can be particularly advantageously applied to an optical module that requires an increase in light intensity for a specific color.

DESCRIPTION OF SYMBOLS 1 Optical module 10 Stem 10A, 10B Main surface 20 Light formation part 30 Electronic cooling module 32 Heat sink 33 Semiconductor pillar 40 Cap 41 Output window 45 Lead pin 51 1st red laser diode 52 2nd red laser diode 53 Green laser diode 54 Blue laser Diode 60 Base plate 60A Mounting surface 60B Main surface 61 First chip mounting area 62 Second chip mounting area 63 Third chip mounting area 64 Fourth chip mounting area 71 First submount 72 Second submount 73 Third submount 74 4th submount 81 1st lens 81A, 82A, 83A, 84A Lens part 81B 1st lens support part 82 2nd lens 82B 2nd lens support part 83 3rd lens 83B 3rd lens support part 84 4th lens 84B 4th Lens support portion 86 First filter 86 1st filter support part 87 2nd filter 87B 2nd filter support part 88 3rd filter 88B 3rd filter support part 89 4th filter 89B 4th filter support part 91 1st photodiode 91A, 92A, 93A, 94A Light-receiving surface 92 Second photodiode 93 Third photodiode 94 Fourth photodiode 105, 106, 107 Island 110 Substrate 110A, 110B Main surface 120 Semiconductor layer 121 Buffer layer 121A Main surface 122 N-side cladding layer 122A Main surface 123 Active layer 123A Main surface 124 p-side cladding layer 124A main surface 124B ridge portion 125 current blocking layer 125A main surface 125B opening 126 p-type layer 126A main surface 127 cap layer 127A main surface 141 p-side electrode 142 n-side electrode 200 red laser diode

Claims (4)

A base member;
A first semiconductor laser element disposed on the base member and including a first semiconductor stacked body;
A second semiconductor laser element disposed on the base member and including a second semiconductor stacked body;
A polarization combining filter disposed on the base member and configured to multiplex light from the first semiconductor laser element and light from the second semiconductor laser element;
The difference between the wavelength of light from the first semiconductor laser element and the wavelength of light from the second semiconductor laser element is 30 nm or less,
The angle formed by the stacking direction of the first semiconductor stack and the stacking direction of the second semiconductor stack is 10 ° or less,
The angle formed by the polarization direction of the light from the first semiconductor laser element incident on the polarization beam combining filter and the polarization direction of the light from the second semiconductor laser element is 80 ° or more and 100 ° or less. module.   An output window that transmits light from the first semiconductor laser element and light from the second semiconductor laser element; the base member; the first semiconductor laser element; the second semiconductor laser element; The optical module according to claim 1, further comprising a protection member surrounding the filter.   The optical module according to claim 1, wherein the first semiconductor laser element and the second semiconductor laser element are red semiconductor laser elements that emit red light. A third semiconductor laser element disposed on the base member and emitting green light;
A fourth semiconductor laser element disposed on the base member and emitting blue light;
It is disposed on the base member and multiplexes the light from the first semiconductor laser element and the second semiconductor laser element, the light from the third semiconductor laser element, and the light from the fourth semiconductor laser element. The optical module according to claim 3, further comprising a multiplexing filter.

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