Light-emitting device

Abstract

To provide a light-emitting device that can prevent stray light generation while keeping manufacturing costs down. [Solution] The device comprises a substrate, a semiconductor light-emitting element mounted on the element mounting surface of the substrate and emitting laser light in a direction opposite to the element mounting surface, and the laser light including a primary beam that forms a beam spot and a secondary beam emitted in a direction different from the primary beam, and a transparent body provided to cover the semiconductor light-emitting element and having an incident region on one of its primary surfaces to which the laser light is incident, wherein the transparent body has a first convex structure on the other primary surface of the transparent body having a convex surface to which the secondary beam reaches.

Description

[Technical Field]

[0001] The present invention relates to a light-emitting device including a vertical resonator type light-emitting element. [Background technology]

[0002] Devices including vertical resonator type light-emitting elements are known. For example, Patent Document 1 discloses an optical module comprising a housing having a recess, a light source including a vertical resonator type light-emitting element disposed within the housing, and an optical element consisting of a microlens array that closes the recess of the housing. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-147493 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In the optical module of Patent Document 1, a light-shielding and diffusing section is formed to shield or diffuse light over an area excluding the central region of the upper surface of the optical element, in order to suppress stray light caused by light other than the light to be emitted leaking from the optical module. Regardless of Patent Document 1, when such a light-shielding and diffusing section is provided in an optical element, it is preferable that this structure can be manufactured inexpensively and easily.

[0005] This invention has been made in view of the above-mentioned points, and aims to provide a light-emitting device that can prevent the generation of stray light while keeping manufacturing costs down. [Means for solving the problem]

[0006] The light-emitting device according to the present invention comprises a substrate; a semiconductor light-emitting element mounted on the element mounting surface of the substrate and emitting laser light in a direction opposite to the element mounting surface, wherein the laser light includes a primary beam that forms a beam spot and a secondary beam emitted in a direction different from the primary beam; and a light-transmitting body provided to cover the semiconductor light-emitting element and having an incident region on one of its primary surfaces to which the laser light is incident, wherein the light-transmitting body has a first convex structure on the other primary surface of the light-transmitting body having a convex surface to which the secondary beam reaches. [Brief explanation of the drawing]

[0007] [Figure 1] This is a top view of the light-emitting device according to Example 1. [Figure 2] This is a cross-sectional view of the light-emitting device according to Example 1. [Figure 3] This is a perspective view of the vertical cavity type surface-emitting laser according to Example 1. [Figure 4] This is a top view of the vertical cavity type surface-emitting laser according to Example 1. [Figure 5] This is a cross-sectional view of a vertical cavity type surface-emitting laser according to Example 1. [Figure 6] This graph shows the relationship between the emission angle of light emitted from the vertical cavity surface-emitting laser of the light-emitting device according to Example 1 and the output power. [Figure 7] This is a cross-sectional view of a light-emitting device according to a modified example of Example 1. [Figure 8] This is a cross-sectional view of a light-emitting device according to a modified example of Example 1. [Figure 9] This is a cross-sectional view of a light-emitting device according to a modified example of Example 1. [Figure 10] This is a cross-sectional view of a light-emitting device according to an application example of Example 1. [Figure 11] This is a cross-sectional view of a light-emitting device according to an application example of Example 1. [Figure 12] This is a cross-sectional view of a light-emitting device according to an application example of Example 1. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and the description of overlapping components will be omitted.

Embodiment

[0009] [Configuration of Light Emitting Device 100] First, the configuration of the light emitting device 100 according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a top view of the light emitting device 100. FIG. 2 is a cross-sectional view of the light emitting device 100 taken along line 2-2 of FIG. 1. In FIG. 2, the vertical direction in the figure is the height direction of the light emitting device 100.

[0010] The light emitting device 100 includes a substrate 11, a vertical cavity surface emitting laser 13 (hereinafter referred to as surface emitting laser 13), and a light transmissive body 15. In FIG. 1, an adhesive member AM for bonding the substrate 11 and the light transmissive body 15 is omitted.

[0011] [Substrate 11] The substrate 11 is an insulating substrate having a rectangular top surface shape. The substrate 11 has a rectangular bottom surface in the central region of the top surface and a recess that is open upward. In other words, the substrate 11 has a flat bottom portion and a frame portion formed in a frame shape along the outer edge of the bottom portion.

[0012] In the light emitting device 100 of this embodiment, the substrate 11 is made of a ceramic such as aluminum nitride (AlN). The substrate 11 may be integrally formed so as to have a recess, or may be formed by joining a flat bottom portion and a frame-shaped frame portion with an adhesive member.

[0013] Furthermore, the substrate 11 is not limited to a substrate having recesses, but a flat mounting substrate may also be used. This mounting substrate has wiring electrodes for mounting electrically connectable wiring and electrical components (semiconductor light-emitting elements such as surface-emitting lasers or edge-emitting lasers, resistors, etc.). When using this mounting substrate, ceramic is preferred as the material, but resin-based FR-4 substrates or aluminum-based Al substrates may also be used. The semiconductor light-emitting elements may be directly bonded to the wiring electrodes as chips, or they may be bonded to the wiring electrodes in a packaged form.

[0014] [Surface-emitting laser 13] The surface-emitting laser 13 is a VCSEL (Vertical Cavity Surface Emitting Laser) made of a group III nitride semiconductor, having a rectangular top surface shape and mounted on wiring electrodes (not shown) provided on the bottom surface of a recess in the substrate 11.

[0015] The surface-emitting laser 13 is configured to be powered from outside the substrate 11 via the aforementioned wiring electrodes, through electrodes (not shown) connected to the wiring electrodes and penetrating the bottom of the substrate 11, and mounting electrodes (not shown) connected to the through electrodes and provided on the lower surface of the substrate 11. The surface-emitting laser 13 may also be mounted on a submount substrate (not shown). That is, a submount substrate may be placed between the substrate 11 and the surface-emitting laser 13.

[0016] Here, the detailed configuration of the surface-emitting laser 13 will be described with reference to Figures 3 to 5. Figure 3 is a perspective view of the surface-emitting laser 13. Figure 4 is a top view of the surface-emitting laser 13. Figure 5 is a cross-sectional view of the surface-emitting laser 13 shown in Figure 4 along line 5-5. In Figure 5, the vertical direction in the figure is the height direction of the surface-emitting laser 13.

[0017] The surface-emitting laser 13 comprises a transparent substrate 21, a first multilayer reflector 22, a semiconductor structural layer EM, an insulating layer 29, a conductive film 31, and a second multilayer reflector 33. In the light-emitting device 100, the surface-emitting laser 13 is mounted in the recess of the substrate 11 in an inverted configuration from the state shown in Figure 5. That is, the surface-emitting laser 13 is mounted so that the upper surface of the second multilayer reflector 33 shown in Figure 5 faces the bottom surface of the recess in the substrate 11.

[0018] The transparent substrate 21 is a flat, transparent substrate with a rectangular top surface. The transparent substrate 21 is also a growth substrate on which semiconductor crystals can be grown on its top surface. The transparent substrate 21 is made of a material that is transparent to blue wavelength light, such as undoped gallium nitride (GaN).

[0019] In the following, the central axis CA will be described as the axis passing through the center of the upper surface of the transparent substrate 21 of the surface-emitting laser 13 and perpendicular to that upper surface. The direction radially away from the central axis CA will be described as the outward direction.

[0020] The first multilayer reflector 22 is a semiconductor multilayer reflector consisting of semiconductor layers grown on the upper surface of the transparent substrate 21. The first multilayer reflector 22 is a so-called distributed Bragg reflector (DBR) in which a high refractive index semiconductor film with a relatively high refractive index and a low refractive index semiconductor film with a lower refractive index than the high refractive index semiconductor film are alternately stacked on the upper surface of the transparent substrate 21.

[0021] The first multilayer reflector 22 is formed, for example, by stacking 42 pairs of high-refractive-index semiconductor films made of GaN and low-refractive-index semiconductor films made of indium aluminum nitride (AlInN) on the upper surface of a transparent substrate 21. The first multilayer reflector 22, having this configuration, is reflective to light in the blue wavelength range. A buffer layer (not shown) made of GaN is provided between the transparent substrate 21 and the first multilayer reflector 22.

[0022] The semiconductor structural layer EM is a stacked structure consisting of multiple semiconductor layers formed on the first multilayer mirror 22. The semiconductor structural layer EM has an n-type semiconductor layer 23 formed on the first multilayer mirror 22, an emissive layer 24 formed on the n-type semiconductor layer 23, an intermediate layer 25 formed on the emissive layer 24, an electron blocking layer 26 formed on the intermediate layer 25, and a p-type semiconductor layer 27 formed on the electron blocking layer 26.

[0023] The n-type semiconductor layer 23, which is a first semiconductor layer having a first conductivity type, is a semiconductor layer formed over the upper surface of the first multilayer reflecting mirror 22. The n-type semiconductor layer 23 is made of GaN and is doped with silicon (Si) as an n-type impurity.

[0024] The n-type semiconductor layer 23 has a so-called mesa-shaped structure, consisting of a flat lower section 23A and a cylindrical upper section 23B that protrudes upward from the center of the lower section 23A along the central axis CA (see Figure 5).

[0025] The light-emitting layer 24 is formed across the upper surface of the upper part 23B of the n-type semiconductor layer 23 and is a semiconductor layer having a quantum well structure in which a well layer made of indium gallium nitride (InGaN) and a barrier layer made of GaN are stacked on top of each other.

[0026] The light-emitting layer 24 is formed such that its light-emitting center lies on the central axis CA. The light-emitting layer 24 emits blue light with a peak wavelength of, for example, 445 nm. In the surface-emitting laser 13 of this embodiment, the thickness of the well layer constituting the light-emitting layer 24 is 4 nm, and the thickness of the barrier layer is 3 nm.

[0027] The intermediate layer 25 is a semiconductor layer made of undoped GaN, formed on top of the well layer formed at the very top of the light-emitting layer 24. In other words, the intermediate layer 25 can be considered the final barrier layer of the light-emitting layer 24. In the surface-emitting laser 13 of this embodiment, the thickness of the intermediate layer 25 is 120 nm.

[0028] The intermediate layer 25 functions as a layer that prevents p-type impurities from diffusing from the electron-blocking layer 26 formed on the intermediate layer 25 to the light-emitting layer 24. In addition to GaN, undoped InGaN or AlGaN may also be used as the material for the intermediate layer 25.

[0029] The electron blocking layer (EBL) 26 is formed across the upper surface of the intermediate layer 25 and is a semiconductor layer made of GaN doped with magnesium (Mg) as a p-type impurity. The electron blocking layer 26 functions as a layer that suppresses the overflow of electrons injected from the n-type semiconductor layer 23 to the light-emitting layer 24 to the p-type semiconductor layer 27.

[0030] The p-type semiconductor layer 27, which is a second semiconductor layer having a second conductivity type, is a semiconductor layer formed over the upper surface of the electron block layer 26. The p-type semiconductor layer 27 is made of AlGaN and is doped with Mg as a p-type impurity.

[0031] As shown in Figure 5, the p-type semiconductor layer 27 has a circular top surface shape and a protruding portion 27P that extends upward in the region including the central axis CA in the center of the top surface. In other words, the annular outer region of the p-type semiconductor layer 27, which is outside the circular central region in the center of the top surface, is recessed below the central region.

[0032] The insulating layer 29 is an electrically insulating coating layer formed in an annular shape along the outer edge of the protrusion 27P on the upper surface of the p-type semiconductor layer 27. The insulating layer 29 covers the upper surface of the p-type semiconductor layer 27 such that only the upper surface of the protrusion 27P is exposed.

[0033] Furthermore, the insulating layer 29 continuously covers the upper surface of the p-type semiconductor layer 27, the side surface of the p-type semiconductor layer 27, the side surface of the electron block layer 26, the side surface of the intermediate layer 25, the side surface of the light-emitting layer 24, and the side surface of the upper part 23B, with its edges reaching the upper surface of the lower part 23A. In other words, the side surface of the semiconductor structure layer EM is covered by the insulating layer 29, except for the lower part 23A of the n-type semiconductor layer 23. Note that the insulating layer 29 may also cover the upper surface and side surface of the lower part 23A of the n-type semiconductor layer 23, except for the n-electrode formation region.

[0034] The insulating layer 29 is made of a material that transmits blue light and has a lower refractive index than the p-type semiconductor layer 27, such as silicon dioxide (SiO2). The refractive index of the p-type semiconductor layer 27 made of AlGaN used in the surface-emitting laser 13 of this embodiment is approximately 2.5, and the refractive index of the insulating layer 29 made of SiO2 is approximately 1.5.

[0035] The conductive film 31 is a transparent conductive film that is both light-transmitting and conductive, in contact with and covering the upper surface of the protrusion 27P of the p-type semiconductor layer 27, while also covering the insulating layer 29 over the region surrounding the protrusion 27P of the p-type semiconductor layer 27.

[0036] The conductive film 31 is made of a metal oxide that is transparent to the blue light emitted from the light-emitting layer 24 of the semiconductor structure layer EM described above, such as indium tin oxide (ITO) or indium zinc oxide (IZO). In the surface-emitting laser 13 of this embodiment, the thickness of the conductive film 31 is 20 nm.

[0037] The n-electrode NE is a metal electrode having an annular upper surface shape formed on the upper surface of the lower part 23A of the n-type semiconductor layer 23. For example, the n-electrode NE is formed by stacking titanium (Ti) and aluminum (Al) in that order on the upper surface of the lower part 23A.

[0038] The p-electrode PE is a metal electrode made of gold (Au) with an annular upper surface shape formed on the upper surface of the conductive film 31. The p-electrode PE is electrically connected to the p-type semiconductor layer 27 via the conductive film 31.

[0039] The second multilayer reflector 33 is a cylindrical dielectric multilayer reflector made of a dielectric layer deposited on the conductive film 31. The second multilayer reflector 33 is formed in contact with the inner surface of the p electrode PE. That is, the diameter of the second multilayer reflector 33 is the aperture diameter of the p electrode PE.

[0040] The second multilayer reflector 33 is a so-called distributed Bragg reflector (DBR) in which a high refractive index dielectric film with a relatively high refractive index and a low refractive index dielectric film with a lower refractive index than the high refractive index dielectric film are alternately stacked on the upper surface of the conductive film 31.

[0041] The second multilayer reflecting mirror 33 is formed, for example, by stacking 10.5 pairs of high-refractive-index dielectric films made of niobium pentoxide (Nb2O5) and low-refractive-index dielectric films made of SiO2 on the upper surface of the conductive film 31. Having this configuration, the second multilayer reflecting mirror 33 is reflective to blue light emitted from the light-emitting layer 24.

[0042] Furthermore, a transparent dielectric layer (not shown) having a circular top surface shape may be formed between the second multilayer reflector 33 and the conductive film 31, for example, as a phase adjustment layer. This dielectric layer may consist of, for example, Nb2O5, tantalum pentoxide (Ta2O5), zinc oxide (ZrO2), titanium oxide (TiO2), hafnium oxide (HfO2), etc.

[0043] In the surface-emitting laser 13 of this embodiment, the diameter W of the upper surface of the protrusion 27P of the p-type semiconductor layer 27. a The diameter W of the upper surface of the second multilayer reflecting mirror 33 is b It is smaller than (see Figure 5). In other words, in a top view of the surface-emitting laser 13, the outer edge of the protrusion 27P is located inside the outer edge of the second multilayer reflecting mirror 33. In the surface-emitting laser 13 of this embodiment, the diameter W a Let the diameter be 5 μm, and the diameter W b This is set to 11 μm.

[0044] In the surface-emitting laser 13, as described above, only the upper surface of the protrusion 27P of the p-type semiconductor layer 27 is electrically connected to the conductive film 31. Therefore, the current flowing from the p-electrode PE to the conductive film 31 is mostly supplied to the semiconductor structural layer EM via the protrusion 27P, which is a low-resistance region, and then flows to the n-electrode NE. In other words, in the surface-emitting laser 13, the protrusion 27P of the p-type semiconductor layer 27 functions as a current-constricting portion that limits the range of current supply so that the current does not spread further.

[0045] In the surface-emitting laser 13, the lower surface of the second multilayer reflector 33 faces the upper surface of the first multilayer reflector 22, with the conductive film 31 and the semiconductor structural layer EM in between. As a result, the first multilayer reflector 22 and the second multilayer reflector 33 form a resonator OC between the first multilayer reflector 22 and the second multilayer reflector 33, with the direction perpendicular to the semiconductor structural layer EM (up and down direction in Figure 5) as the resonator length direction.

[0046] When a voltage is applied to the n electrode NE and the p electrode PE, and a current flows between the n electrode NE and the p electrode PE, a current flows through the light-emitting layer 24 of the semiconductor structure layer EM. When it reaches a threshold current, which is a predetermined current value, the intensity of the blue light emitted from the light-emitting layer 24 increases rapidly.

[0047] The blue light emitted from the light-emitting layer 24 upon reaching the threshold current is repeatedly reflected between the first multilayer mirror 22 and the second multilayer mirror 33, that is, within the resonator OC, until it reaches a resonant state (i.e., laser oscillation occurs).

[0048] In the surface-emitting laser 13, the reflectivity of the first multilayer mirror 22 for blue light is slightly lower than that of the second multilayer mirror 33 for blue light. Therefore, a portion of the blue light resonating in the resonator OC passes through the first multilayer mirror 22 and the transparent substrate 21 and is emitted downwards in Figure 5. In other words, the lower surface of the transparent substrate 21 is the light emission surface of the surface-emitting laser 13.

[0049] Furthermore, an anti-reflective coating (AR) is formed on the lower surface of the transparent substrate 21, consisting of Nb2O5 and SiO2 layers. The anti-reflective coating (AR) is a so-called AR coating that suppresses the reflection of blue light emitted from the transparent substrate 21 upwards in Figure 5.

[0050] [Emitted light from surface-emitting laser 13] Here, the light emitted from the surface-emitting laser 13 of the light-emitting device 100 of this embodiment will be explained using Figure 2. In the light-emitting device 100 of this embodiment, the n electrode NE and p electrode PE of the surface-emitting laser 13 are bonded to the bottom of the recess in the substrate 11 via a conductive adhesive member (not shown) so that the upper surface of the second multilayer reflector 33 of the surface-emitting laser 13 faces the bottom of the recess in the substrate 11. Therefore, when the surface-emitting laser 13 is mounted on the bottom of the recess in the substrate 11, light is emitted upward from the surface-emitting laser 13.

[0051] In the surface-emitting laser 13 of this embodiment, as described above, the diameter W of the protruding portion 27P of the p-type semiconductor layer 27 a However, the diameter W of the second multilayer reflecting mirror 33 b It is smaller than this. Because the surface-emitting laser 13 has this configuration, the laser light emitted from the surface-emitting laser 13 is divided into a principal beam ML (solid line in the figure) which is emitted along the central axis CA due to resonance in the resonator OC, and a secondary beam SL (dotted line in the figure) which is emitted separately from the principal beam ML at an angle θ with the central axis CA, as shown in Figure 2. In other words, the secondary beam SL is laser light emitted in a different direction from the principal beam ML.

[0052] The primary beam ML emitted from the surface-emitting laser 13 forms a circular beam spot. The secondary beam SL emitted from the surface-emitting laser 13 is emitted in an annular region surrounding the primary beam ML. Therefore, for example, when the light emitted from the surface-emitting laser 13 is projected onto a screen, the projected light has a light distribution pattern consisting of a circular primary beam ML and an annular secondary beam SL surrounding the primary beam ML.

[0053] Figure 6 is a graph showing the relationship between the amount of light emitted from the surface-emitting laser 13 of this embodiment and the emission angle. In Figure 6, the amount of light for each emission angle is shown when the emission angle of light along the central axis of the surface-emitting laser 13 is set to 0°.

[0054] Figure 6 shows that the light emitted from the surface-emitting laser 13 in this embodiment includes a light component with an angle of approximately 40° with respect to the central axis CA, in addition to the main light component ML, which has an emission angle of around 0°. In the surface-emitting laser 13 of this embodiment, this light component with an angle θ = 40° is emitted as the secondary light SL.

[0055] Here, using Figure 5, the generation mechanism of secondary light SL in the surface-emitting laser 13 will be explained. When light that has reached a resonant state in the resonator OC reaches the protrusion 27P of the p-type semiconductor layer 27, it undergoes diffraction at the protrusion 27P. That is, the light that has passed through the protrusion 27P contains an optical component along the central axis CA and an optical component that is at an angle to the central axis CA.

[0056] Of the light transmitted through the protrusion 27P, the light component along the central axis CA is ultimately emitted from the surface-emitting laser 13 as the principal light ML. On the other hand, a portion of the light component that is at an angle to the central axis CA is incident on the second multilayer mirror 33 and reflected by the second multilayer mirror 33.

[0057] At this time, W when the emission wavelength is λ b When light components incident on the second multilayer mirror 33 at an angle θ satisfying sinθ=mλ (where m is an integer) are reflected by the second multilayer mirror 33, they become light with aligned phases. In other words, when light components with an angle θ with respect to the central axis CA are reflected by the second multilayer mirror 33, they become light that reinforces each other.

[0058] As a result, in the surface-emitting laser 13 of this embodiment, the secondary light SL, which is the laser beam, is emitted in the angular direction θ. In the surface-emitting laser 13 of this embodiment, the angle θ is approximately 40°, as described above.

[0059] In the light-emitting device 100 of the present embodiment, in order for the secondary light SL to be emitted from the surface-emitting laser 13, for light with a peak wavelength of 445 nm, the diameter W of the protruding portion 27P of the p-type semiconductor layer 27 a is preferably less than 10 μm, and the diameter W of the second multilayer film mirror 33 b is preferably 10 μm or more and 20 μm or less.

[0060] [Light-transmitting body 15] Referring to FIGS. 1 and 2 again. The light-transmitting body 15 is an optical element that closes the opening of the recess of the substrate 11 so as to seal the surface-emitting laser 13 in the recess of the substrate 11. The light-transmitting body 15 is composed of a base portion 35, a condensing portion 36 formed on the upper surface of the base portion 35, and a reflecting portion 37 (first convex structure).

[0061] In the light-emitting device 100 of the present embodiment, the light-transmitting body 15 is made of a material having transparency with respect to the blue light emitted from the surface-emitting laser 13, such as an acrylic resin, a polycarbonate resin, an epoxy resin, a silicone resin, or glass made of SiO2. In the light-emitting device 100 of the present embodiment, the refractive index of the light-transmitting body 15 is 1.516.

[0062] In the light-emitting device 100 of the present embodiment, the recess of the substrate 11 and the outside of the light-transmitting body 15 are filled with air (refractive index = 1.000). Therefore, when the light transmitted through the light-transmitting body 15 is emitted to the outside of the light-transmitting body 15 beyond the critical angle, the light is totally reflected at the interface between the light-transmitting body 15 and the air.

[0063] In the light-emitting device 100 of the present embodiment, the light-transmitting body 15 only needs to have a refractive index that causes total reflection at the interface between the light-transmitting body 15 and the air. For example, the refractive index of the light-transmitting body 15 is preferably greater than 1.050, preferably greater than 1.300, and more preferably greater than 1.400.

[0064] The base 35 of the light-transmitting body 15 is a flat plate-shaped portion with a rectangular upper surface. The lower surface of the base 35 is joined to the upper surface of the frame portion that forms the recess of the substrate 11 via an adhesive member AM. As a result, the surface-emitting laser 13 is sealed within the recess of the substrate 11.

[0065] The light-emitting device 100 is configured such that the principal light ML emitted from the surface-emitting laser 13 is incident on the central region of the lower surface of the base 35. In other words, the central region of the lower surface of the base 35 is the principal light incident region, which is the region into which the principal light ML emitted from the surface-emitting laser 13 is incident.

[0066] The light-collecting portion 36 of the light-transmitting body 15 is a roughly hemispherical convex structure that protrudes from the center of the upper surface of the base portion 35 so as to pass through the central axis CA. The light-collecting portion 36 is formed in the principal light emission region on the upper surface of the base portion 35, which is the region where the principal light ML that has entered from the principal light incidence region and passed through the base portion 35 is emitted. In other words, the light-collecting portion 36 is provided in the central region of the upper surface of the base portion 35.

[0067] The focusing unit 36 ​​concentrates the principal light ML emitted from the surface-emitting laser 13 as it passes through the base 35 and reaches the focusing unit 36, and then emits it upward in Figure 2. In other words, the focusing unit 36 ​​functions as a focusing lens.

[0068] The reflective portion 37 (first convex structure) of the translucent body 15 protrudes from the upper surface of the base portion 35 and has a convex structure with an annular upper surface shape. In the light-emitting device 100 of this embodiment, the reflective portion 37 is formed on the upper surface of the base portion 35, surrounding the light-collecting portion 36 and in contact with the light-collecting portion 36.

[0069] The secondary light SL that has passed through the base 35 is incident on the reflecting portion 37. The convex surface of the reflecting portion 37 is shaped such that the angle of incidence when the secondary light SL is incident exceeds the critical angle, and in the light-emitting device 100 of this embodiment, the convex surface is a curved surface having a predetermined curvature. Therefore, when the secondary light SL emitted from the surface-emitting laser 13 passes through the base 35 and reaches the convex surface of the reflecting portion 37, total internal reflection of the secondary light SL occurs at the convex surface.

[0070] Specifically, in the light-emitting device 100 of this embodiment, the secondary light SL undergoes two total internal reflections on the convex surface of the reflecting portion 37, as shown by the dashed line in Figure 2, before proceeding to the base portion 35. The secondary light SL that has proceeded to the base portion 35 proceeds into the recess of the substrate 11 and is reflected or absorbed by the substrate 11. In other words, the secondary light SL that has entered the reflecting portion 37 is returned to the recess of the substrate 11 without being emitted outside the light-emitting device 100.

[0071] As shown in Figure 6, the secondary light SL is the component of the laser light emitted from the surface-emitting laser 13 that has the second highest light intensity after the primary light ML. Therefore, if, for example, the secondary light SL is emitted from the light-emitting device 100 together with the primary light ML in the upper part of Figure 2, the contrast of the primary light ML may decrease, and the desired light distribution pattern may not be obtained. In other words, the secondary light SL can become stray light for the primary light ML.

[0072] In this embodiment, the light-emitting device 100 suppresses the emission of secondary light SL from the light-emitting device 100 by totally reflecting the secondary light SL emitted from the surface-emitting laser 13 at the reflector 37 provided on the base 35. In other words, the contrast of the main light ML can be maintained by suppressing the emission of light components that could become stray light.

[0073] As shown in Figure 6, of the light emitted from the light-emitting device 100, the light components other than the main light ML (emission angle around 0°) and the secondary light SL (emission angle around 40°) have almost no light intensity. In other words, there are almost no light components other than the secondary light SL that could affect the contrast of the main light ML.

[0074] Therefore, as in the light-emitting device 100 of this embodiment, even by simply providing the reflecting portion 37 in the region through which the secondary light SL passes on the upper surface of the base portion 35, it is possible to suppress the emission of light components that could become stray light for the main light ML as much as possible.

[0075] Furthermore, in the light-emitting device 100 of this embodiment, the light-transmitting body 15 is molded, for example, using a mold, so that the base 35, the light-collecting part 36, and the reflecting part 37 are integrated. Therefore, compared to the case where a light-reflecting film made of a different material from the base 35, such as metal, is provided on the base 35 as a measure against stray light, a reduction in manufacturing costs can be expected.

[0076] Therefore, according to the light-emitting device 100 of this embodiment, when the laser light emitted from the surface-emitting laser 13 includes a main light ML and a secondary light SL, the use of a light-transmitting body 15 equipped with a reflecting section 37 makes it possible to suppress the generation of stray light while keeping manufacturing costs down.

[0077] In this embodiment of the light-emitting device 100, the thickness T1 of the base 35 of the translucent body 15 is 0.400 mm, and the distance D1 between the upper surface of the surface-emitting laser 13 and the lower surface of the base 35 is 0.675 mm. In addition, in this embodiment of the light-emitting device 100, the distance L1 between the vertex of the light-collecting portion 36 and the vertex of the reflecting portion 37 of the translucent body 15 in a plan view is 1.050 mm, the thickness T2 of the reflecting portion 37 from the lower surface of the base 35 is 0.650 mm, and the radius of curvature of the reflecting portion 37 is 0.450 mm. Furthermore, the Abbe number (V), which is an index representing the degree of light dispersion, is also used. d ) is set to 64.14.

[0078] In the light-emitting device 100 of this embodiment, the convex surface of the reflecting portion 37 is aspherical, and the radius of curvature R of the reflecting portion 37 satisfies the following equation 1. Furthermore, in the modified examples described later, all reflecting portions 37 with curved surfaces are aspherical, and their radius of curvature satisfies equation 1.

[0079]

number

[0080] Here, x is the distance in the optical axis direction from the apex of the convex surface (lens surface) to the base 35, h is the width of the reflecting part 37 on the upper surface of the base 35 in the direction perpendicular to the optical axis, R is the radius of paraxial curvature at the apex of the lens surface, k is the cone constant, and c2, c4, c6, and c8 are polynomial coefficients. In the light-emitting device 100 of this embodiment, k, c2, c4, c6, and c8 are all set to 0.000.

[0081] In this embodiment, the light-emitting device 100 has an annular shape for the reflective portion 37 (first convex structure), but the reflective portion 37 may be formed only in the areas where the secondary light SL is to be reflected. In that case, the reflective portion 37 may be formed only in the areas where the secondary light SL is to be reflected, and the other areas may be flat surfaces. In that case, the secondary light SL will be emitted to the outside from the flat surfaces above, but as long as the amount of light is not such that it is recognized as stray light, there is no problem with the secondary light SL leaking to the outside.

[0082] For example, the reflecting portion 37 only needs to be able to totally reflect at least a portion of the secondary light SL emitted from the surface-emitting laser 13, and the secondary light SL on the upper surface of the base portion 35 does not need to be continuously formed over an entire area. For example, the reflecting portion 37 does not need to be formed symmetrically with respect to the central axis CA in a plan view, and may be formed discontinuously in multiple locations.

[0083] Furthermore, in the light-emitting device 100 of this embodiment, the light-transmitting body 15 only needs to function as an optical element and does not necessarily need to seal the recess in the substrate 11. Also, the light-transmitting body 15 may be positioned inside the frame portion that forms the recess in the substrate 11.

[0084] In the light-emitting device 100 of this embodiment, the surface-emitting laser 13 has an insulating layer 29 that covers from the upper surface of the p-type semiconductor layer 27 excluding the protruding portion 27P to the side surface of the n-type semiconductor layer 23 excluding the lower part 23A. However, the insulating layer 29 does not necessarily need to be formed. For example, the p-type semiconductor layer 27 may be formed up to the region where the insulating layer 29 is formed in this embodiment, and the portion corresponding to the region where the insulating layer 29 is formed in this embodiment may have high resistance, thereby performing the insulating function.

[0085] For example, consider a case where the outer region outside the protrusion 27P on the upper surface of the p-type semiconductor layer 27 is formed by dry etching. In this case, the outer region becomes electrically inert due to etching damage, i.e., it becomes a high-resistance region with higher electrical resistance compared to the protrusion 27P. Therefore, even without forming an insulating layer 29 in the outer region, the outer region functions as an insulating part.

[0086] [Example 1] Next, a modification 1 of the light-emitting device 100 of Example 1 will be described using Figure 7. Figure 7 is a cross-sectional view of the light-emitting device 110 according to modification 1. The light-emitting device 110 differs from that of Example 1 in the configuration of the light-transmitting body 15, and is otherwise similar to the light-emitting device 100.

[0087] In this modified example of the light-emitting device 110, the light-collecting portion 36 and the reflecting portion 37 are provided on the upper surface of the base portion 35, spaced apart from each other. In the light-emitting device 110, both the light-collecting portion 36 and the reflecting portion 37 have a hemispherical cross-section.

[0088] In this modified light-emitting device 110, the distance L1 is set to 1.000 mm, the thickness T2 to 0.550 mm, and the radius of curvature of the reflecting part 37 to 0.500 mm. The thickness T1 and distance D1 are the same as in Example 1. Also, the Abbe number (V) described above d The cone constant k is set to 64.14. Additionally, the cone constant k is set to 0.600, and the polynomial coefficients c2, c4, c6, and c8 are set to 0.000.

[0089] In the modified light-emitting device 110, the secondary light SL emitted from the surface-emitting laser 13 is totally reflected by the reflector 37, as shown in Figure 7, and then passes through the base 35 and is emitted to the side of the light-emitting device 110. In other words, in the modified light-emitting device 110, the secondary light SL is not returned to the recess of the substrate 11 but is emitted in a direction different from above the light-emitting device 110.

[0090] According to this modified light-emitting device 110, by configuring the light-transmitting body 15 in this way, it is possible to suppress the emission of secondary light SL upward from the light-emitting device 110. In other words, it is possible to prevent light other than the primary light ML from being emitted upward from the light-emitting device 110.

[0091] [Differentiation 2] Next, a modified example 2 of the light-emitting device 100 of Example 1 will be described using Figure 8. Figure 8 is a cross-sectional view of the light-emitting device 120 according to Modified Example 2. The light-emitting device 120 differs from Example 1 in the configuration of the light-transmitting body 15, but is otherwise similar to the light-emitting device 100.

[0092] In the modified light-emitting device 120, the light-transmitting body 15 consists only of a base 35 and a reflecting portion 37. That is, the principal light ML incident on the base 35 passes through the base 35 and is emitted from the light-emitting device 110.

[0093] In the modified light-emitting device 120, the reflecting portion 37 has a substantially trapezoidal cross-section. More specifically, the reflecting portion 37 has a flat top surface, an inner surface that slopes outward, and an outer surface that is perpendicular to the top surface.

[0094] In this modified light-emitting device 120, the distance L1 between the central axis CA and the lower end of the inner surface of the reflecting part 37 is 0.930 mm, the distance L2 between the central axis CA and the upper end of the inner surface of the reflecting part 37 is 1.030 mm, and the distance L3 between the central axis CA and the upper end of the outer surface of the reflecting part 37 is 1.800 mm. Furthermore, the Abbe number (V) described above d The value of ) is set to 64.14. In addition, the cone constant k and the polynomial coefficients c2, c4, c6, and c8 are all set to 0.000.

[0095] Furthermore, in the modified light-emitting device 120, the thickness T1 of the base portion 35 is set to 0.400 mm, and the thickness T2 of the reflecting portion 37 from the upper surface of the base portion 35 is set to 0.400 mm. The distance D1 is the same as in Example 1.

[0096] In the modified light-emitting device 120, as shown in Figure 8, the secondary light SL is emitted to the outside after passing through the base 35, and then incident on the reflecting part 37 from outside the light-transmitting body 15. The secondary light SL that is incident on the reflecting part 37 is totally reflected on the upper surface of the reflecting part 37, emitted to the outside, then incident on the base 35, and returned to the recess in the substrate 11.

[0097] According to this modified light-emitting device 120, by configuring the translucent body 15 in this way, it is possible to suppress the emission of secondary light SL upward from the light-emitting device 120. In other words, it is possible to prevent light other than the primary light ML from being emitted upward from the light-emitting device 120.

[0098] [Difference 3] Next, a third modification of the light-emitting device 100 of Example 1 will be described using Figure 9. Figure 9 is a cross-sectional view of the light-emitting device 130 according to the third modification. The light-emitting device 130 differs from that of Example 1 in the configuration of the light-transmitting body 15, but is otherwise similar to the light-emitting device 100.

[0099] In the modified light-emitting device 130, the translucent body 15 is composed of a base portion 35, a reflective portion 37, and a protrusion 39 formed on the lower surface of the base portion 35. In the modified light-emitting device 130, the reflective portion 37 has a hemispherical cross-section.

[0100] In the modified light-emitting device 130, the protrusion 39 protrudes from the lower surface of the base 35 and has a convex structure with an annular upper surface shape. In the light-emitting device 130, the protrusion 39 has a triangular cross-section. The protrusion 39 is formed in an annular region surrounding the incident region into which the principal light ML is incident on the lower surface of the base 35.

[0101] In this modified light-emitting device 130, the distance L1 between the central axis CA and the vertex of the reflecting portion 37 is set to 0.901 mm, the distance L2 between the central axis CA and the vertex of the convex portion 39 is set to 1.207 mm, and the distance L3 between the central axis CA and the outer edge of the convex portion 39 is set to 1.392 mm. Furthermore, the Abbe number (V) described above is also set. dThe value of ) is set to 64.17. In addition, the cone constant k and the polynomial coefficients c2, c4, c6, and c8 are all set to 0.000.

[0102] Furthermore, in this modified light-emitting device 130, the thickness T2 of the reflective portion 37 from the lower surface of the base portion 35 is set to 0.553 mm, and the thickness T3 of the convex portion 39 from the upper surface of the base portion 35 is set to 0.555 mm. The distance D1 is the same as in Example 1.

[0103] As shown in Figure 9, when the secondary light SL, which has been totally reflected by the reflecting portion 37, reaches the lower surface of the base portion 35, the secondary light SL is guided through the protrusion 39, refracted by its inclined surface, and directed toward the bottom of the substrate 11. Therefore, with the light-emitting device 130 of this modified example, the secondary light SL, which has been totally reflected by the reflecting portion 37, can be guided into the recess of the substrate 11, thereby allowing control of the light ray path of the secondary light SL and more reliably suppressing its emission to the outside.

[0104] In this embodiment and its modified example, the secondary light SL is defined as light emitted from the surface-emitting laser 13 at an angle of 40°, but the emission angle of the secondary light SL is not limited to this. Therefore, in this embodiment and its modified example, the formation manner of the reflective portion 37, for example, the formation position and shape of the reflective portion 37, can be appropriately changed according to the emission angle of the secondary light SL.

[0105] Furthermore, although a surface-emitting laser 13 is used as the light source in this embodiment and its modified form, the light source is not limited to this; for example, an edge-emitting laser may also be used, and these are collectively referred to as semiconductor light-emitting devices.

[0106] [Application Example 1] Next, Application Example 1 of Embodiment 1 and Modification Example 1 will be described using Figure 10. Figure 10 is a cross-sectional view of the light-emitting device 210 according to Application Example 1. The light-emitting device 210 includes a mounting substrate 41, a light-emitting device 110 of Modification Example 1 arranged on the mounting substrate 41, and a light-receiving element 43.

[0107] The mounting substrate 41 is a flat substrate with a rectangular top surface. The mounting substrate 41 is a circuit board on which wiring for connecting to the light-emitting device 110 and the light-receiving element 43 is provided on the base material, which is an FR-4 substrate or an Al substrate.

[0108] The light-receiving element 43 has a rectangular top surface shape and is mounted on the mounting substrate 41 at a distance from the light-emitting device 110. The light-receiving element 43 is a photodiode (PD) that receives light emitted from the outside and generates an electrical signal corresponding to the intensity of the received light. Note that the number of light-receiving elements 43 is not limited to one, and multiple elements may be provided.

[0109] In the light-emitting device 210, the secondary light SL emitted outside the light-emitting device 110 via the light-transmitting body 15 is incident on a light-receiving element 43 mounted on the upper surface of the mounting substrate 41. As a result, in the light-emitting device 210 of this application example, the light intensity of the secondary light SL can be monitored by the light-receiving element 43.

[0110] There is a positive correlation between the light intensity of the primary light ML and the light intensity of the secondary light SL. Therefore, by monitoring the output value output by the photodetector 43 that receives the secondary light SL, it becomes possible to monitor the output of the surface-emitting laser 13. For example, the light intensity of the primary light ML can be adjusted based on the light intensity (or output value) of the secondary light SL, or if it is detected that the light intensity (or output value) of the secondary light SL is zero or less than a predetermined threshold, this can be used to determine if the surface-emitting laser 13 has failed.

[0111] In the light-emitting device 210 of this application example, the end face of the translucent body 15 is perpendicular to the bottom surface. However, if the end face is positioned upwards and made into an inclined surface that widens, the secondary light SL can be refracted and the position of the light-receiving element 43 can be positioned closer to the light-emitting device 110. Also, in the light-emitting device 210 of this application example, the secondary light SL is emitted from the end face of the translucent body 15. However, for example, the length of the translucent body 15 in the width direction (left-right direction in the figure) can be extended so that the secondary light SL is emitted from the bottom surface of the translucent body 15.

[0112] [Application Example 2] Next, using Figure 11, Application Example 2 of Example 1 and Modification Example 2 will be described. Figure 11 is a cross-sectional view of the light-emitting device 220 according to Application Example 2. In the light-emitting device 220, the light-transmitting body 15 covers the surface-emitting laser 13 and the light-receiving element 43 arranged on the mounting substrate 41. Note that in Figure 11, the support portion that supports the light-transmitting body 15 is omitted.

[0113] In the light-emitting device 220 of this application example, the secondary light SL emitted from the surface-emitting laser 13 and totally reflected by the light-transmitting body 15 is incident on a photodetector 43 mounted on the upper surface of the mounting substrate 41, similar to the application example 1. Therefore, in the light-emitting device 220 of this application example, the output of the surface-emitting laser 13 can be monitored by monitoring the output value output by the photodetector 43 that receives the secondary light SL.

[0114] [Application Example 3] Next, with reference to Figure 12, Application Example 3 of Example 1 and Modification 3 will be described. Figure 12 is a cross-sectional view of the light-emitting device 230 according to Application Example 3. The light-emitting device 230 differs from Modification 3 in that it is provided with a light-receiving element 43 on the bottom surface of the substrate 11, and is otherwise the same as Modification 3.

[0115] In the light-emitting device 230 of this application example, the secondary light SL emitted from the surface-emitting laser 13 and totally reflected by the light-transmitting body 15 is incident on the photodetector 43 mounted on the bottom surface of the substrate 11. Therefore, in the light-emitting device 230 of this application example, the output of the surface-emitting laser 13 can be monitored by monitoring the output value output by the photodetector 43 that receives the secondary light SL.

[0116] In this application example, the light-emitting device 230 refracts the secondary light SL toward the surface-emitting laser 13 by a protrusion 39 provided on the lower surface of the base 35. However, as shown in Figure 2, the path of the secondary light SL can be controlled even by simply reflecting it twice at the reflector 37. Therefore, if there is sufficient space to mount the light-receiving element 43, the lower surface of the base 35 may be a flat surface. In other words, the protrusion 39 may not be necessary. [Explanation of Symbols]

[0117] 100, 110, 120, 130, 140 Light-emitting devices 11 circuit boards 13. Surface-emitting laser (vertical cavity type light-emitting element) 15 Optical functional layer 21 Transparent substrate 22 First multilayer reflecting mirror 23 n-type semiconductor layer 24. Emitting layer 25 Middle Class 26 Electron Block Layer 27 p-type semiconductor layer 29 Insulating layer 31 Conductive film 33. Second multilayer reflecting mirror 35 base 36 Light-gathering section 37 Reflective section (first convex structure) 39. Convex portion (second convex structure) NE n electrode PE p electrode

Claims

1. circuit board and A semiconductor light-emitting element is mounted on the element mounting surface of the substrate, emits laser light in a direction opposite to the element mounting surface, and the laser light includes a primary beam that forms a beam spot and a secondary beam emitted in a direction different from the primary beam. A transparent body having an incident region on one main surface that covers the semiconductor light-emitting element, wherein the laser light is incident on the transparent body, The light-emitting device is characterized in that the light-transmitting body has a first convex structure on the other main surface of the light-transmitting body, which has a convex surface to which the secondary light reaches.

2. The light-emitting device according to claim 1, characterized in that at least a portion of the secondary light is totally reflected by the convex surface of the first convex structure.

3. The light-emitting device according to claim 1 or 2, characterized in that the first convex structure is formed in an annular shape so as to surround the principal light transmission region through which the principal light is transmitted.

4. The light-emitting device according to claim 1 or 2, characterized in that the first convex structure has a curved surface.

5. The light-emitting device according to claim 1 or 2, characterized in that the upper surface of the first convex structure is a flat surface.

6. The light-emitting device according to claim 1 or 2, characterized in that it has a second convex structure that protrudes from one of the main surfaces at the position where the secondary light, which has passed through the first convex structure of the light-transmitting body, reaches.

7. The light-emitting device according to claim 6, characterized in that the second convex structure is formed in an annular shape so as to surround the principal light incident region into which the principal light is incident.

8. The light-emitting device according to claim 1 or 2, characterized in that it has a light-collecting structure formed protruding from the principal light-transmitting region of the other principal surface through which the principal light is transmitted.

9. The substrate comprises at least one light-receiving element mounted around the element mounting surface, The light-emitting device according to claim 1 or 2, characterized in that the light-receiving element receives the secondary light reflected by the first convex structure.

10. The light-transmitting body has a second convex structure that protrudes from one of its main surfaces at the position where the secondary light, having passed through the first convex structure, reaches. The light-emitting device according to claim 9, characterized in that the light-receiving element receives the secondary light transmitted via the second convex structure.

11. The light-emitting device according to claim 1 or 2, characterized in that the semiconductor light-emitting element is a vertical resonator type light-emitting element.

12. The aforementioned semiconductor light-emitting device is Transparent substrate and A first multilayer reflecting mirror formed on the transparent substrate, A semiconductor structural layer comprising a first semiconductor layer made of a semiconductor having a first conductivity type formed on the first multilayer reflecting mirror, an emissive layer formed on the first semiconductor layer, and a second semiconductor layer formed on the emissive layer having a second conductivity type opposite to the first conductivity type, A second multilayer reflector is formed on the semiconductor structure layer and constitutes a resonator with the first multilayer reflector, It has, The semiconductor light-emitting element is mounted such that the element mounting surface of the substrate and the upper surface of the second multilayer reflector face each other. The light-emitting device according to claim 1 or 2, characterized in that the semiconductor structure layer has an insulating portion formed in an annular region when viewed from above, and the region surrounded by the annular region is located inward from the outer edge of the second multilayer reflector when viewed from above.

13. circuit board and A vertical resonator type light-emitting element is mounted on the element mounting surface of the substrate and emits laser light in a direction opposite to the element mounting surface, A light-transmitting body having a convex structure on one main surface that covers the vertical resonator type light-emitting element, having an incident region on which the laser light is incident, and on the other main surface, having a convex surface in a region other than the principal light transmission region which is the region through which the principal light that forms the beam spot of the laser light is transmitted, The aforementioned vertical resonator type light-emitting element is Transparent substrate and A first multilayer reflecting mirror formed on the transparent substrate, A semiconductor structural layer comprising a first semiconductor layer made of a semiconductor having a first conductivity type formed on the first multilayer reflecting mirror, an emissive layer formed on the first semiconductor layer, and a second semiconductor layer formed on the emissive layer having a second conductivity type opposite to the first conductivity type, A second multilayer reflector is formed on the semiconductor structure layer and constitutes a resonator with the first multilayer reflector, It has, The vertical resonator type light-emitting element is mounted such that the element mounting surface and the upper surface of the second multilayer reflector face each other. The light-emitting device is characterized in that the semiconductor structure layer has an insulating portion formed in an annular region when viewed from above, and the region surrounded by the annular region is located inward from the outer edge of the second multilayer reflecting mirror when viewed from above.

14. The substrate comprises at least one light-receiving element mounted around the element mounting surface, The light-emitting device according to claim 13, characterized in that the light-receiving element receives light reflected by the convex structure.

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