JP2018011024A - Light receiving element and optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light receiving element capable of suppressing generation of stray light, and to provide an optical module including the light receiving element.SOLUTION: A light receiving element 94 includes a semiconductor layer having a light receiving surface 94A, and an electrode 6 placed on the semiconductor layer. In the plan view from a direction perpendicular to the light receiving surface 94A, the electrode 6 extends along the outer periphery of the light receiving surface 94A. In the plan view from a direction perpendicular to the light receiving surface 94A, a first notch 6A penetrating the electrode 6 in the width direction is formed in the electrode 6.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light receiving element and an optical module.

  By receiving light in a state where a depletion layer is formed between a p-type layer and an n-type layer made of a semiconductor, an amount of carriers corresponding to the amount of incident light is generated, and a light receiving element (semiconductor light receiving device) that extracts this as current Element) is known. In such a light receiving element, a structure in which electrodes are formed along the outer periphery of the light receiving surface of the semiconductor layer (the surface on which light enters the semiconductor layer) may be employed (see, for example, Patent Document 1). .

JP 2009-267251 A

  As described above, when the electrode is formed along the outer periphery of the light receiving surface, a part of the light irradiated to the light receiving element is reflected by the electrode, and a phenomenon (stray light) in which the light reaches an unintended place may occur. Depending on the device in which the light receiving element is installed, stray light may not be preferable in relation to the function of the device.

  Accordingly, it is an object to provide a light receiving element capable of suppressing the generation of stray light and an optical module including the light receiving element.

  The light receiving element according to the present invention includes a semiconductor layer having a light receiving surface and an electrode disposed on the semiconductor layer. The electrode extends along the outer periphery of the light receiving surface when seen in a plan view from a direction perpendicular to the light receiving surface. As viewed in a plan view from a direction perpendicular to the light receiving surface, the electrode has a first notch that penetrates the electrode in the width direction.

  According to the light receiving element, generation of stray light can be suppressed.

It is a schematic sectional drawing which shows the structure of a light receiving element. It is a schematic plan view which shows the structure of a light receiving element. It is a schematic plan view which shows the modification of the structure of a light receiving element. 1 is a schematic perspective view showing the structure of an optical module in Embodiment 1. FIG. 1 is a schematic perspective view showing the structure of an optical module in Embodiment 1. FIG. FIG. 3 is a schematic plan view showing the structure of the optical module in the first embodiment. FIG. 7 is a schematic cross-sectional view corresponding to a cross section taken along line VII-VII in FIG. 6. It is the schematic which shows the relationship between the shape of the light in a cross section in alignment with line segment VIII-VIII of FIG. 7, and a lens. It is a schematic plan view which shows arrangement | positioning of a light receiving element. It is a schematic plan view which shows arrangement | positioning of the light receiving element which has a structure of a modification. 6 is a schematic perspective view showing a structure of an optical module according to Embodiment 2. FIG.

[Description of Embodiment of Present Invention]
First, embodiments of the present invention will be listed and described. The light receiving element of this application is provided with the semiconductor layer which has a light-receiving surface, and the electrode arrange | positioned on a semiconductor layer. The electrode extends along the outer periphery of the light receiving surface when seen in a plan view from a direction perpendicular to the light receiving surface. As viewed in a plan view from a direction perpendicular to the light receiving surface, the electrode has a first notch that penetrates the electrode in the width direction.

  In the light receiving element of the present application, a first notch that penetrates the electrode in the width direction is formed in the electrode extending along the outer periphery of the light receiving surface. Therefore, when the incident direction (light path) of light with respect to the light receiving element is constant, by arranging the light receiving element so that the optical path and the first notch overlap when viewed in a plan view from a direction perpendicular to the light receiving surface, The reflection of light by the electrode is reduced. As a result, the generation of stray light is suppressed. Thus, according to the light receiving element of the present application, generation of stray light can be suppressed.

  In the light receiving element, when viewed in a plan view from a direction perpendicular to the light receiving surface, the electrode is positioned so as to face the first notch with the light receiving surface interposed therebetween, and extends through the electrode in the width direction. Two notches may be formed. By forming the second notch and arranging the light receiving element so that the optical path overlaps the first notch and the second notch, the reflection of light by the electrode is further reduced.

  The optical module of the present application includes a light forming portion that forms light, and a protective member that has an exit window that transmits light from the light forming portion and is disposed so as to surround the light forming portion. The light forming portion is mounted on the base member, a semiconductor light emitting element mounted on the base member, a lens mounted on the base member and converting a spot size of light emitted from the semiconductor light emitting element, and the base member. And the light receiving element of the present application which is disposed between the semiconductor light emitting element and the lens in the emission direction of the semiconductor light emitting element and directly receives light from the semiconductor light emitting element. The light receiving element is configured so that the light from the semiconductor light emitting element is incident on the light receiving surface in a state where the light path of the light from the semiconductor light emitting element overlaps the first notch when viewed in a plane perpendicular to the light receiving surface. Be placed.

  In the optical module of the present application, the light receiving element receives light from the semiconductor light emitting element in a state where the optical path of the light from the semiconductor light emitting element overlaps the first notch when viewed in a plan view from a direction perpendicular to the light receiving surface. It arrange | positions so that it may inject into a surface. Therefore, reflection of light by the electrode of the light receiving element is reduced. As a result, according to the optical module of the present application, generation of stray light can be suppressed.

  In the optical module, the light forming portion includes a plurality of semiconductor light emitting elements mounted on the base member, and a plurality of lenses mounted on the base member and disposed corresponding to each of the plurality of semiconductor light emitting elements. The light receiving element mounted on the base member and disposed corresponding to at least one of the plurality of semiconductor light emitting elements, and mounted on the base member, from the plurality of semiconductor light emitting elements. And a filter for multiplexing the light.

  In this way, by arranging a plurality of semiconductor light emitting elements in a single package and allowing light from these to be multiplexed in the package, it is possible to combine light from a plurality of packages. Therefore, it is possible to reduce the size of the device in which the optical module is used. As the filter, for example, a wavelength selective filter, a polarization synthesis filter, or the like can be employed.

  In the optical module, the plurality of semiconductor light emitting elements may include a semiconductor light emitting element that emits red light, a semiconductor light emitting element that emits green light, and a semiconductor light emitting element that emits blue light. By doing so, these lights can be combined to form light of a desired color.

  In the optical module, the light receiving element emits light in a region other than a region in which a spot size is converted by the lens corresponding to the at least one semiconductor light emitting device among light emitted from the at least one semiconductor light emitting device. You may arrange | position in the position which can receive light.

  In this way, by adopting a structure where the light receiving element receives the light whose spot size is not converted by the lens, that is, the light that is not used as the light emitted from the optical module, the amount of the emitted light from the optical module is reduced. The intensity of the light emitted from the semiconductor light emitting element can be grasped without doing so. Further, in a structure in which a plurality of semiconductor light emitting elements are arranged in the single package and light from these is combined in the package, such a structure is adopted, and the light is emitted from the semiconductor light emitting elements. The light intensity can be adjusted more accurately. This is due to the following reasons.

  In the case where a plurality of semiconductor light emitting elements are arranged in a single package and the light from these is combined in the package, the light receiving element that is to receive the light emitted from one semiconductor light emitting element is used. A phenomenon in which light emitted from other semiconductor light emitting elements is mixed, that is, light crosstalk occurs. Further, due to the crosstalk, there arises a problem that the intensity of light from the semiconductor light emitting element that should be grasped originally in the light receiving element cannot be grasped accurately.

  According to the inventor's study, the largest cause of this crosstalk is that the light emitted from one semiconductor light emitting element is received by the light receiving element that is emitted from the other semiconductor light emitting element, and is inside the protective member. The reflected light (reflected light) enters through the optical path through which the light emitted from one semiconductor light emitting element should pass. Since this reflected light passes through an optical path through which light emitted from one semiconductor light emitting element should pass, the reflected light travels through a region where the spot size is converted by a lens corresponding to one semiconductor light emitting element. In other words, between the at least one semiconductor light emitting element and the corresponding lens, other semiconductor light emitting elements are provided in a region other than the region where the spot size is converted by the lens corresponding to the at least one semiconductor light emitting device. The reflected light from the light does not enter. Therefore, the light receiving element can receive light in a region other than a region in which the spot size is converted by the lens corresponding to the at least one semiconductor light emitting device among the light emitted from the at least one semiconductor light emitting device. By arranging them in this way, the occurrence of crosstalk can be suppressed. As a result, the intensity of light emitted from the semiconductor light emitting element can be adjusted more accurately.

  In the optical module, the light receiving element may be disposed at a position where a photocurrent obtained by receiving light emitted from the at least one semiconductor light emitting element is 1 μA or more. By doing in this way, the intensity | strength of the light from a semiconductor light-emitting element can be grasped | ascertained accurately. In order to grasp the intensity of light from the semiconductor light emitting element with higher accuracy, the light receiving element may be arranged at a position where the photocurrent becomes 10 μA or more.

  In the optical module, the semiconductor light emitting element may be a laser diode. By doing in this way, the emitted light with little variation in wavelength can be obtained.

  In the above optical module, the light forming unit may further include an electronic cooling module disposed in contact with the base member. By doing so, the optical module can be used even in an environment where the temperature is high.

[Details of the embodiment of the present invention]
(Embodiment 1)
Next, an embodiment of a light receiving element according to the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a cross-sectional view taken along line II in FIG. 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 FIG. 1, a first photodiode 94 as a first light receiving element includes a high concentration n-type layer 3, an n-type layer 4, a p-type region 5, a p-side electrode 6, and an n-side electrode 7. And comprising.

  The high-concentration n-type layer 3 has an n-type conductivity by including an n-type impurity. N-type layer 4 is disposed in contact with first main surface 3A of the high-concentration n-type layer. The n-type layer 4 has an n-type conductivity by containing n-type impurities at a lower concentration than the high-concentration n-type layer 3. The p-type region 5 is formed inside the n-type layer 4 so as to include the first main surface 4A of the n-type layer 4. The p-type region 5 has a p-type conductivity by containing a p-type impurity. High-concentration n-type layer 3, n-type layer 4, and p-type region 5 constitute a semiconductor layer. On the main surface of the semiconductor layer opposite to the n-side electrode 7, a light receiving surface 94A for allowing light to enter the semiconductor layer from the outside is formed.

  The n-side electrode 7 is disposed in contact with the second main surface 3B of the high concentration n-type layer 3. The n-side electrode 7 is made of a conductor such as metal. The n-side electrode 7 is in ohmic contact with the high concentration n-type layer 3. The p-side electrode 6 is disposed in contact with the main surface of the semiconductor layer opposite to the n-side electrode 7. The p-side electrode 6 is disposed in contact with the p-type region 5 exposed on the main surface of the semiconductor layer. The p-side electrode 6 is made of a conductor such as metal. The p-side electrode 6 is in ohmic contact with the p-type region 5.

  When light enters from the light receiving surface 94A, an amount of carriers corresponding to the amount of light incident on the p-type region 5 and the n-type layer 4 is generated. By taking this out as a current through the p-side electrode 6 and the n-side electrode 7, the amount of incident light can be grasped.

  FIG. 2 is a plan view of the first photodiode 94 shown in FIG. 1 viewed from a direction perpendicular to the light receiving surface 94A. Referring to FIG. 2, p-side electrode 6 extends along the outer periphery of light receiving surface 94A. The p-side electrode 6 is disposed so as to surround the outer periphery of the light receiving surface 94A. The p-side electrode 6 has an annular (annular) shape. The p-side electrode 6 has a bonding region 6E for forming an electrical junction. The p-side electrode 6 is formed with a first notch 6A that penetrates the p-side electrode 6 in the width direction. That is, the p-side electrode 6 has an annular shape interrupted at the first notch 6A.

  When the incident direction (optical path) of light with respect to the first photodiode 94 is constant, the first photodiode 94 has a light path and a first notch portion of the incident light as viewed in a plan view from a direction perpendicular to the light receiving surface 94A. By being arranged so as to overlap with 6A, it is a light receiving element (semiconductor light receiving element) capable of reducing the reflection of light by the p-side electrode 6 and suppressing the generation of stray light.

  FIG. 3 shows a modification of the structure of the first photodiode 94. FIG. 3 is a plan view of the first photodiode 94 viewed from the same viewpoint as FIG. Referring to FIG. 3, the first photodiode 94 in the modification basically has the same structure as the first photodiode 94 described with reference to FIGS. 1 and 2 and has the same effect. Play. However, the first photodiode 94 in the present modification is different from the first photodiode 94 described with reference to FIGS. 1 and 2 in that it has a pair of notches.

  Specifically, in the first photodiode 94 according to the modification, the p-side electrode 6 faces the first notch 6A across the light receiving surface 94A when seen in a plane perpendicular to the light receiving surface 94A. The 2nd notch part 6B which is located in this way and penetrates the p side electrode 6 in the width direction is formed. That is, the first cutout portion 6A and the second cutout portion 6B are located on the same straight line when viewed in a plan view from a direction perpendicular to the light receiving surface 94A. The p-side electrode 6 is separated into two regions. A bonding region 6E is formed in one region of the p-side electrode 6, and a bonding region 6F is formed in the other region.

  In this way, the second notch portion 6B is formed, and the first photodiode 94 is arranged so that the optical path overlaps the first notch portion 6A and the second notch portion 6B. Light reflection is further reduced.

  Next, an embodiment of an optical module according to the present invention will be described with reference to FIGS. FIG. 5 is a view corresponding to a state in which the cap 40 of FIG. 4 is removed.

  Referring to FIGS. 4 and 5, 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 10 </ b> A of stem 10 and forms 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 51 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. 5 and 6, light forming unit 20 includes a base plate 60 that is a base member having a plate shape. The base plate 60 has one main surface 60A having a rectangular shape when seen in a plan view. The base plate 60 includes a base region 61 and a chip mounting region 62. The chip mounting area 62 is formed in an area including one short side of one main surface 60A and one long side connected to the short side. The thickness of the chip mounting area 62 is larger than that of the base area 61. As a result, the height of the chip mounting area 62 is higher than that of the base area 61. In the chip mounting area 62, a first chip that is an area that is thicker (higher in height) than an adjacent area in an area on the opposite side of the one short side to the side connected to the one long side. A mounting region 63 is formed. In the chip mounting area 62, the second chip is an area that is thicker (higher in height) than the adjacent area in the area opposite to the side connected to the one short side of the one long side. A mounting region 64 is formed.

  A flat plate-like first submount 71 is disposed on the first chip mounting area 63. A red laser diode 81 as a first semiconductor light emitting element is disposed on the first submount 71. On the other hand, on the second chip mounting region 64, a flat plate-like second submount 72 and a third submount 73 are arranged. When viewed from the second submount 72, the third submount 73 is disposed on the opposite side of the connection portion between the one long side and the one short side. On the second submount 72, a green laser diode 82 as a second semiconductor light emitting element is disposed. A blue laser diode 83 as a third semiconductor light emitting element is disposed on the third submount 73. The optical axis heights of the red laser diode 81, the green laser diode 82, and the blue laser diode 83 (distance between the reference surface and the optical axis when one main surface 60A of the base plate 60 is used as a reference surface; in the Z-axis direction) The distance from the reference plane is adjusted by the first submount 71, the second submount 72, and the third submount 73 to coincide with each other.

  On the base region 61 of the base plate 60, a fourth submount 74, a fifth submount 75, and a sixth submount 76 are arranged. On the fourth submount 74, the fifth submount 75, and the sixth submount 76, the first photodiode 94 as the first light receiving element, the second photodiode 95 as the second light receiving element, and the third submount, respectively. A third photodiode 96 as a light receiving element is disposed. The first photodiode 94 has, for example, the structure described with reference to FIG. 1 and FIG. 2 or the structure of the modification described with reference to FIG. The second photodiode 95 and the third photodiode 96 have the same structure as the first photodiode 94.

  The heights of the first photodiode 94, the second photodiode 95, and the third photodiode 96 (the red laser diode 81 and the green laser diode 82) are respectively determined by the fourth submount 74, the fifth submount 75, and the sixth submount 76. And the distance to the optical axis of the blue laser diode 83; the distance in the Z-axis direction). Details of the height adjustment of the first photodiode 94, the second photodiode 95, and the third photodiode 96 will be described later. The first photodiode 94, the second photodiode 95, and the third photodiode 96 are installed at positions that directly receive light from the red laser diode 81, the green laser diode 82, and the blue laser diode 83, respectively. In the present embodiment, a light receiving element is arranged corresponding to each of all semiconductor light emitting elements. The first photodiode 94, the second photodiode 95, and the third photodiode 96 are photodiodes that can receive red, green, and blue light, respectively. The first photodiode 94 is disposed between the red laser diode 81 and the first lens 91 in the emission direction of the red laser diode 81. The second photodiode 95 is disposed between the green laser diode 82 and the second lens 92 in the emission direction of the green laser diode 82. The third photodiode 96 is disposed between the blue laser diode 83 and the third lens 93 in the emission direction of the blue laser diode 83.

  On the base region 61 of the base plate 60, a first lens holding portion 77, a second lens holding portion 78, and a third lens holding portion 79, which are convex portions, are formed. A first lens 91, a second lens 92, and a third lens 93 are disposed on the first lens holding unit 77, the second lens holding unit 78, and the third lens holding unit 79, respectively. The first lens 91, the second lens 92, and the third lens 93 have lens portions 91A, 92A, and 93A whose surfaces are lens surfaces. In the first lens 91, the second lens 92, and the third lens 93, the lens portions 91A, 92A, and 93A and regions other than the lens portions 91A, 92A, and 93A are integrally molded. By the first lens holding part 77, the second lens holding part 78, and the third lens holding part 79, the central axes of the lens parts 91A, 92A, 93A of the first lens 91, the second lens 92, and the third lens 93, that is, the lens The optical axes of the portions 91A, 92A, 93A are adjusted to coincide with the optical axes of the red laser diode 81, the green laser diode 82, and the blue laser diode 83, respectively. The first lens 91, the second lens 92, and the third lens 93 convert the spot size of light emitted from the red laser diode 81, the green laser diode 82, and the blue laser diode 83, respectively. The spot size is converted by the first lens 91, the second lens 92, and the third lens 93 so that the spot sizes of the light emitted from the red laser diode 81, the green laser diode 82, and the blue laser diode 83 coincide.

  A first filter 97 and a second filter 98 are disposed on the base region 61 of the base plate 60. The first filter 97 and the second filter 98 each have a flat plate shape having principal surfaces parallel to each other. The first filter 97 and the second filter 98 are, for example, wavelength selective filters. The first filter 97 and the second filter 98 are dielectric multilayer filters. More specifically, the first filter 97 transmits red light and reflects green light. The second filter 98 transmits red light and green light, and reflects blue light. As described above, the first filter 97 and the second filter 98 selectively transmit and reflect light having a specific wavelength. As a result, the first filter 97 and the second filter 98 multiplex the light emitted from the red laser diode 81, the green laser diode 82, and the blue laser diode 83. The first filter 97 and the second filter 98 are disposed on a first projecting region 88 and a second projecting region 89, which are convex portions formed on the base region 61, respectively.

  Referring to FIG. 6, red laser diode 81, light receiving surface 94 </ b> A of first photodiode 94, lens portion 91 </ b> A of first lens 91, first filter 97, and second filter 98 emit light from red laser diode 81. They are arranged along a straight line along the direction (in the X-axis direction). The green laser diode 82, the light receiving surface 95A of the second photodiode 95, the lens portion 92A of the second lens 92, and the first filter 97 are aligned on a straight line along the light emission direction of the green laser diode 82 (Y-axis direction). Arranged side by side). The blue laser diode 83, the light receiving surface 96A of the third photodiode 96, the lens portion 93A of the third lens 93, and the second filter 98 are aligned on a straight line along the light emission direction of the blue laser diode 83 (Y-axis direction). Arranged side by side). That is, the emission direction of the red laser diode 81 and the emission direction of the green laser diode 82 and the blue laser diode 83 intersect. More specifically, the emission direction of the red laser diode 81 is orthogonal to the emission directions of the green laser diode 82 and the blue laser diode 83. The emission direction of the green laser diode 82 is a direction along the emission direction of the blue laser diode 83. More specifically, the emission direction of the green laser diode 82 and the emission direction of the blue laser diode 83 are parallel. The main surfaces of the first filter 97 and the second filter 98 are inclined with respect to the light emission direction of the red laser diode 81. More specifically, the main surfaces of the first filter 97 and the second filter 98 are inclined by 45 ° with respect to the light emission direction (X-axis direction) of the red laser diode 81.

Next, the operation of the optical module 1 in the present embodiment will be described. Referring to FIG. 6, red light emitted from the red laser diode 81 travels along the optical path L _1. At this time, a part of the red light directly enters the light receiving surface 94A of the first photodiode 94. As a result, the intensity of the red light emitted from the red laser diode 81 is grasped, and the intensity of the red light is adjusted based on the difference between the grasped light intensity and the intensity of the target light to be emitted. . The red light that has passed over the first photodiode 94 enters the lens portion 91A of the first lens 91, and the spot size of the light is converted. Specifically, for example, red light emitted from the red laser diode 81 is converted into collimated light. The red light whose spot size has been converted in the first lens 91 travels along the optical path L ₁ and enters the first filter 97. Since the first filter 97 transmits red light, the light emitted from the red laser diode 81 further travels along the optical path L ₂ and enters the second filter 98. The second filter 98 is for transmitting the red light, the light emitted from the red laser diode 81 further proceeds along the optical path L _3, through the exit window 41 of the cap 40 of the optical module 1 to the outside And exit.

Green light emitted from the green laser diode 82 travels along the optical path L _4. At this time, part of the green light is directly incident on the light receiving surface 95 </ b> A of the second photodiode 95. Thereby, the intensity of the green light emitted from the green laser diode 82 is grasped, and the intensity of the green light is adjusted based on the difference between the grasped light intensity and the intensity of the target light to be emitted. . The green light that has passed over the second photodiode 95 enters the lens portion 92A of the second lens 92, and the spot size of the light is converted. Specifically, for example, green light emitted from the green laser diode 82 is converted into collimated light. The green light whose spot size has been converted by the second lens 92 travels along the optical path L ₄ and enters the first filter 97. The first filter 97 for reflecting green light, the light emitted from the green laser diode 82 joins the optical path L _2. As a result, the green light is combined with the red light, travels along the optical path L ₂ , and enters the second filter 98. The second filter 98 for transmitting the green light, the light emitted from the green laser diode 82 further proceeds along the optical path L _3, through the exit window 41 of the cap 40 to the outside of the optical module 1 And exit.

Blue light emitted from the blue laser diode 83 travels along the optical path L _5. At this time, part of the blue light is directly incident on the light receiving surface 96 </ b> A of the third photodiode 96. As a result, the intensity of the blue light emitted from the blue laser diode 83 is grasped, and the intensity of the blue light is adjusted based on the difference between the grasped light intensity and the intensity of the target light to be emitted. . The blue light that has passed over the second photodiode 95 enters the lens portion 93A of the third lens 93, and the spot size of the light is converted. Specifically, for example, blue light emitted from the blue laser diode 83 is converted into collimated light. The blue light whose spot size has been converted in the third lens 93 travels along the optical path L ₅ and enters the second filter 98. The second filter 98 for reflecting the blue light, the light emitted from the blue laser diode 83 joins the optical path L _3. As a result, the blue light is combined with the red light and the green light, travels along the optical path L ₃ , and exits 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 the optical module 1 in the present embodiment, part of the light emitted from the red laser diode 81, the green laser diode 82, and the blue laser diode 83 is converted into the first lens 91, the second lens 92, and the third lens, respectively. Light is directly received by the first photodiode 94, the second photodiode 95, and the third photodiode 96 disposed between the lens 93. Therefore, it is possible to accurately grasp the light intensity and adjust the light intensity with high accuracy. As a result, red, green, and blue light are accurately combined at a desired intensity ratio, and light of a desired color can be formed with high accuracy.

  Next, details of the height adjustment of the first photodiode 94, the second photodiode 95, and the third photodiode 96 will be described by taking the second photodiode 95 as an example. The positional relationship between the first photodiode 94 and the third photodiode 96 with respect to the red laser diode 81 and the blue laser diode 83 is the same as the positional relationship with respect to the green laser diode 82 of the second photodiode 95 described below.

  Referring to FIGS. 7 and 8, green light 2 emitted from green laser diode 82 is perpendicular to one main surface 60A of base plate 60 in a cross section perpendicular to the optical axis (cross section in FIG. 8). It has an elliptical shape whose major axis is the direction (Z-axis direction). The lens portion 92A of the second lens 92 has a circular shape in a cross section perpendicular to the optical axis. Therefore, as shown in FIG. 8, it is preferable to arrange the second lens 92 so that the circle constituting the outer peripheral surface of the lens portion 92 </ b> A is inscribed in the ellipse corresponding to the light 2 in the cross section perpendicular to the optical axis. In this case, the light 2 includes a region 2A that is spot-converted by the second lens 92 and a region 2B that is not spot-converted.

  Then, referring to FIG. 7, the second photo diode 95 has a light receiving surface 95 </ b> A that can receive light in the region 2 </ b> B other than the region 2 </ b> A whose spot size is converted by the second lens 92. A diode 95 is disposed. More specifically, the light receiving surface 95A can receive the light in the region 2B other than the region 2A in which the spot size is converted by the second lens 92, so that the emission part 82A of the green laser diode 82 and the second photo An angle θ formed by a straight line connecting the light receiving surface 95A of the diode 95 and the optical axis 2C of the green laser diode 82 is adjusted. The angle θ can be adjusted by changing the thickness of the fifth submount 75 and the mounting position of the second photodiode 95 on the fifth submount 75. Thus, by adopting a structure in which the second photodiode 95 receives light that is not spot-sized converted by the second lens 92, that is, light in the region 2B that is not used as light emitted from the optical module 1, the optical module 1 The intensity of the light emitted from the green laser diode 82 can be grasped without reducing the amount of light emitted from the green laser diode 82.

  In addition, by arranging the second photodiode 95 as described above, the intensity of the light emitted from the green laser diode 82 can be accurately grasped. The reason for this will be described below. As described above, when a structure in which a plurality of semiconductor light emitting elements (red laser diode 81, green laser diode 82, and blue laser diode 83) are arranged in a single package and light from these is combined is adopted. There may be a problem that the intensity of light cannot be accurately grasped due to crosstalk of light. Regarding this problem, a case where the intensity of light from the green laser diode 82 is grasped will be described.

Referring to FIG. 6, the red light emitted from red laser diode 81 travels along optical path L ₁ as described above and originally passes through first filter 97. However, some of the red light travels along the optical path L ₆ is reflected at the first filter 97. The light is reflected by the inner wall surface 40A of the cap 40, along the optical path L ₆ is incident on the first filter 97, it passes. Then, the light travels along the optical path L ₇ and reaches the second photodiode 95 through the second lens 92. In this way, the reflected light of the red light can be mixed into the second photodiode 95 that should originally receive the intensity of the green light. This is the biggest cause of crosstalk.

Here, the reflected light of the mixed red light is a region in which the spot size is converted by the lens portion 92A of the second lens 92 because the light emitted from the green laser diode 82 passes through the path toward the first filter 97. 2A (see FIG. 7). That is, in the optical module 1 of the present embodiment in which the second photodiode 95 is arranged so as to be able to receive light in the region 2B other than the region 2A in which the spot size is converted by the second lens 92, the above path The red reflected light that has passed through is not received by the second photodiode 95. Therefore, occurrence of crosstalk can be suppressed, and the intensity of light emitted from the green laser diode 82 can be accurately grasped and adjusted. The occurrence of crosstalk can be effectively reduced by appropriately adjusting the angle θ. Specifically, the occurrence of crosstalk can be effectively reduced by adjusting the angle θ to be equal to or greater than the effective angle θ ₀ of the second lens 92. On the other hand, if the angle θ is too large, the amount of reflected light (red light) received by the second photodiode 95 is sufficiently suppressed, but light (green light) from the second photodiode 95 is received. The photocurrent obtained in this way becomes small, and it becomes difficult to accurately grasp the intensity of light from the second photodiode 95. The angle θ is preferably set so that the value of the photocurrent obtained by receiving the light from the second photodiode 95 is 1 μA or more. In this way, the intensity of light from the second photodiode 95 can be accurately grasped. In order to grasp the intensity of the light from the second photodiode 95 more accurately, the angle θ is adjusted so that the value of the photocurrent obtained by receiving the light from the second photodiode 95 becomes 10 μA or more. The second photodiode 95 is preferably disposed.

  In the optical module 1 according to the present embodiment, the first photodiode 94 corresponding to the red laser diode 81 and the third photodiode 96 corresponding to the blue laser diode 83 also correspond to the green laser diode 82. The second photodiode 95 is disposed in the same manner. Therefore, the occurrence of crosstalk is suppressed, and the intensity of red, green, and blue light is appropriately adjusted. As a result, light having a desired color can be formed with high accuracy.

  Next, details of the arrangement of the first photodiode 94, the second photodiode 95, and the third photodiode 96 will be described using the first photodiode 94 as an example. The second photodiode 95 and the third photodiode 96 are similar to the arrangement of the first photodiode 94 in the relationship with the green laser diode 82 and the blue laser diode 83, respectively, in the relationship with the red laser diode 81 described below. It is arranged in the arrangement mode.

Referring to FIG. 9, the first photodiode 94, in plan view from a direction perpendicular to the light receiving surface 94A, in a state where the optical path L ₁ of the light from the red laser diode 81 overlaps the first notch 6A The light from the red laser diode 81 is arranged to enter the light receiving surface 94A. Referring to FIG. 10, when the structure of the above modification is employed, first photodiode 94 has an optical path of light from red laser diode 81 as seen in a plan view from a direction perpendicular to light receiving surface 94A. L ₁ is in a state of overlapping the first notch 6A and the second notch portion 6B, the light from the red laser diode 81 is arranged to be incident on the light receiving surface 94A.

  In the optical module 1 of the present application, the first photodiode 94, the second photodiode 95, and the third photodiode 96 are respectively viewed as a red laser diode 81 and a green laser diode 82 in plan view from a direction perpendicular to the light receiving surface. The light from the red laser diode 81, the green laser diode 82, and the blue laser diode 83 is incident on the light receiving surface in a state where the optical path of the light from the blue laser diode 83 overlaps the first notch (and the second notch). It arrange | positions so that it may inject. Therefore, reflection of light by the electrodes of the first photodiode 94, the second photodiode 95, and the third photodiode 96 (for example, the p-side electrode 6 of the first photodiode 94) is reduced. As a result, the optical module 1 of the present embodiment is an optical module in which the generation of stray light is suppressed.

(Embodiment 2)
Next, Embodiment 2 which is another embodiment of the optical module according to the present invention will be described. With reference to FIG. 11 and FIG. 5, the optical module 1 in the present embodiment has basically the same structure as that of the first embodiment and has the same effects. However, the optical module 1 in the second embodiment is different from that in the first embodiment in that it further includes an electronic cooling module 30.

  Specifically, referring to FIG. 11, the optical module 1 in the second 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 31, a heat radiating plate 32, and a semiconductor pillar 33 arranged side by side between the heat absorbing plate 31 and the heat radiating plate 32 with electrodes interposed therebetween. The heat absorbing plate 31 and the heat radiating plate 32 are made of alumina, for example. The endothermic plate 31 is disposed in contact with the other main surface 60 </ b> B 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). And by supplying an electric current to the electronic cooling module 30, the heat of the base plate 60 which contacts the heat absorption plate 31 moves to the stem 10, and the base plate 60 is cooled. As a result, the temperature rise of the red laser diode 81, the green laser diode 82, and the blue laser diode 83 is suppressed. Thereby, the optical module 1 can be used even in an environment where the temperature is high, for example, when it is mounted on an automobile. Further, by maintaining the temperatures of the red laser diode 81, the green laser diode 82, and the blue laser diode 83 within an appropriate range, light of a desired color can be accurately formed.

  The submount is made of a material having a thermal expansion coefficient close to that of an element mounted on the submount, and can be made of, for example, AlN, SiC, Si, diamond, or the like. Moreover, as a material which comprises a stem and a cap, iron, copper, etc. which are materials with high heat conductivity may be employ | adopted, for example, AlN, CuW, CuMo, etc. may be employ | adopted.

  In the above embodiment, the case where light from three semiconductor light emitting elements having different emission wavelengths is combined has been described. However, the number of semiconductor light emitting elements may be one or two, and four or more. There may be. In the above embodiment, the case where a laser diode is employed as the semiconductor light emitting element has been described. However, for example, a light emitting diode may be employed as the semiconductor light emitting element. Moreover, although the case where a wavelength selective filter was employ | adopted as the 1st filter 97 and the 2nd filter 98 was illustrated in the said embodiment, these filters may be a polarization | polarized-light synthesis filter, for example.

  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 light receiving element and the optical module of the present application can be particularly advantageously applied to a light receiving element and an optical module that are required to suppress stray light.

DESCRIPTION OF SYMBOLS 1 Optical module 2 Light 2A, 2B Area | region 2C Optical axis 3 High concentration n-type layer 3A 1st main surface 3B 2nd main surface 4 n-type layer 4A main surface 5 p-type area | region 6 p side electrode 6A 1st notch 6B 2nd notch part 6E, 6F Bonding area | region 7 N side electrode 10 Stem 10A One main surface 10B The other main surface 20 The light formation part 30 The electronic cooling module 31 The heat sink 32 The heat sink 33 The semiconductor pillar 40 Cap 40A Inner wall surface 41 Outgoing Window 51 Lead pin 60 Base plate 60A One main surface 60B The other main surface 61 Base region 62 Chip mounting region 63 First chip mounting region 64 Second chip mounting region 71 First submount 72 Second submount 73 Third submount 74 4th submount 75 5th submount 76 6th submount 77 1st lens holding part 78 2nd lens holding part 79 3rd lens holding part DESCRIPTION OF SYMBOLS 1 Red laser diode 82 Green laser diode 82A Output part 83 Blue laser diode 88 1st protrusion area | region 89 2nd protrusion area | region 91 1st lens 92 2nd lens 93 3rd lens 91A, 92A, 93A Lens part 94 1st photodiode 95 Second photodiode 96 Third photodiode 94A, 95A, 96A Light-receiving surface 97 First filter 98 Second filter

Claims (9)

A semiconductor layer having a light receiving surface;
An electrode disposed on the semiconductor layer,
The electrode extends along the outer periphery of the light receiving surface when viewed in a plane perpendicular to the light receiving surface,
The light receiving element, wherein the electrode is formed with a first notch penetrating the electrode in the width direction when viewed in a plan view from a direction perpendicular to the light receiving surface.   As viewed in a plan view from a direction perpendicular to the light receiving surface, the electrode is positioned so as to face the first notch with the light receiving surface interposed therebetween, and a second cut that penetrates the electrode in the width direction. The light receiving element according to claim 1, wherein a notch is formed. A light forming part for forming light;
A protective member that has an exit window that transmits light from the light forming portion and is disposed so as to surround the light forming portion,
The light forming part is
A base member;
A semiconductor light emitting device mounted on the base member;
A lens mounted on the base member and converting a spot size of light emitted from the semiconductor light emitting element;
3. The device according to claim 1, mounted on the base member, disposed between the semiconductor light emitting element and the lens in an emission direction of the semiconductor light emitting element, and directly receiving light from the semiconductor light emitting element. A light receiving element, and
The light receiving element is configured to receive light from the semiconductor light emitting element in a state where an optical path of light from the semiconductor light emitting element overlaps the first notch when viewed in a plan view from a direction perpendicular to the light receiving surface. An optical module arranged to be incident on a surface. The light forming part is
A plurality of the semiconductor light emitting elements mounted on the base member;
A plurality of the lenses mounted on the base member and disposed corresponding to each of the plurality of semiconductor light emitting elements;
The light receiving element mounted on the base member and disposed corresponding to at least one of the plurality of semiconductor light emitting elements;
The optical module according to claim 3, further comprising: a filter mounted on the base member and configured to multiplex light from the plurality of semiconductor light emitting elements.   5. The light according to claim 4, wherein the plurality of semiconductor light emitting elements include the semiconductor light emitting element that emits red light, the semiconductor light emitting element that emits green light, and the semiconductor light emitting element that emits blue light. module.   The light receiving element is a position capable of receiving light in a region other than a region in which a spot size is converted by the lens corresponding to the at least one semiconductor light emitting device among light emitted from the at least one semiconductor light emitting device. The optical module according to claim 3, wherein the optical module is disposed on the optical module.   The optical module according to claim 6, wherein the light receiving element is disposed at a position where a photocurrent obtained by receiving light emitted from the at least one semiconductor light emitting element is 1 μA or more.   The optical module according to claim 3, wherein the semiconductor light emitting element is a laser diode.   The optical module according to claim 3, wherein the light forming unit further includes an electronic cooling module disposed in contact with the base member.

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