Light-emitting device and light-emitting module

Abstract

The present invention provides a light-emitting device capable of controlling the output of light emitted from a vertical resonator type light-emitting device without impairing the utilization efficiency of the emitted light, and a light-emitting module including the light-emitting device. [Solution] The device comprises a substrate having a recess, a vertical resonator type light-emitting element made of a group III nitride semiconductor mounted on the bottom surface of the recess of the substrate and emitting laser light toward the opening of the recess, wherein the laser light includes a primary beam that forms a beam spot and a secondary beam emitted in a different direction from the primary beam and having a lower optical output than the primary beam, a light-receiving element mounted on the bottom surface of the recess of the substrate, a light-transmitting plate that closes the opening of the recess, and a light-reflecting structure formed in a region of the light-transmitting plate other than the primary beam incident region, which is the region into which the primary beam is incident.

Description

[Technical Field]

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

[0002] Light-emitting devices including vertical resonator type light-emitting elements are known. For example, Patent Document 1 discloses a lighting device comprising a light source package having a substrate, a light source unit including a vertical resonator type light-emitting element, a light-receiving unit and a plate-shaped cover member, and a light-emitting control unit that controls the emission of light from the light source unit. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 7318180 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the lighting device disclosed in Patent Document 1, a reflective film is formed over the area of ​​the cover member except for the area directly above the light source. A portion of the light emitted from the light source is reflected by the reflective film and received by the light receiving unit. When the received light is outside a predetermined intensity range, the light emission control unit stops the light emission from the light source, assuming that the cover member has fallen off or is damaged.

[0005] In the lighting device described in Patent Document 1, a vertical-cavity surface-emitting laser (VCSEL) is used as the light source, and it is suggested that all light-emitting points emit light simultaneously with approximately the same light intensity, thus creating a surface light source. In this case, although the goal is to emit all the light from the light source to the outside, some of the light is reflected by the reflective film, which may reduce the output of the light emitted to the outside. To compensate for this reduction in output, it is necessary to increase the area of ​​the package or to supply more current to the light source, for example.

[0006] Furthermore, in the lighting device described in Patent Document 1, if, for example, a light-emitting diode (LED) is used as the light source, a large amount of stray light may be generated due to its light distribution characteristics, which may reduce the utilization efficiency of the light emitted from the lighting device.

[0007] The present invention has been made in view of the above-mentioned points, and aims to provide a light-emitting device and a light-emitting module including the light-emitting device that can control the output of the emitted light without impairing the utilization efficiency of the emitted light of a vertical resonator type light-emitting device. [Means for solving the problem]

[0008] The light-emitting device according to the present invention is characterized by comprising: a substrate having a recess; a vertical resonator type light-emitting element mounted on the bottom surface of the recess of the substrate, which emits laser light toward the opening of the recess and the laser light includes a primary beam that forms a beam spot and a secondary beam emitted in a different direction from the primary beam and having a lower optical output than the primary beam, a light-receiving element mounted on the bottom surface of the recess of the substrate, a light-transmitting plate that closes the opening of the recess, and a light-reflecting structure formed in a region of the light-transmitting plate other than the primary beam incident region, which is the region into which the primary beam is incident.

[0009] Furthermore, the light-emitting module according to the present invention includes a substrate having a recess, a vertical resonator type light-emitting element mounted on the bottom surface of the recess of the substrate and emitting laser light toward the opening of the recess, and the laser light being made of a group III nitride semiconductor and including a primary light that forms a beam spot and a secondary light emitted in a different direction from the primary light and having a lower optical output than the primary light, a light-emitting device having a photodetector mounted on the bottom surface of the recess of the substrate, a light-transmitting plate that closes the opening of the recess, and a light-reflecting structure formed in a region of the light-transmitting plate other than the primary light incidence region which is the region into which the primary light is incident, and an output control unit electrically connected to each of the vertical resonator type light-emitting element and the photodetector and capable of controlling the output of the laser light of the vertical resonator type light-emitting element, wherein the output control unit controls the output of the laser light of the vertical resonator type light-emitting element according to the intensity of the light received by the photodetector. [Brief explanation of the drawing]

[0010] [Figure 1] It is a top view of the light-emitting device according to Embodiment 1. [Figure 2] It is a cross-sectional view of the light-emitting device according to Embodiment 1. [Figure 3] It is a perspective view of the vertical cavity surface emitting laser according to Embodiment 1. [Figure 4] It is a top view of the vertical cavity surface emitting laser according to Embodiment ........... [Figure 5] It is a cross-sectional view of the vertical cavity surface emitting laser according to Embodiment 1. [Figure 6] It is a graph showing the relationship between the emission angle and the output of the light emitted from the vertical cavity surface emitting laser of the light-emitting device according to Embodiment 1. [Figure 7] It is a block diagram showing the configuration of the light-emitting module as an application example of the light-emitting device according to Embodiment 1. [[ID=XX]] [[ID=XX]] [Figure 8] It is a top view of the light-emitting device according to a modified example of Embodiment 1. [Figure 9] It is a top view of the light-emitting device according to a modified example of Embodiment 1. [Figure 10] It is a top view of the light-emitting device according to a modified example of Embodiment 1. [Figure 11] It is a cross-sectional view of the light-emitting device according to Embodiment 2.

Mode for Carrying Out the Invention

[0011] 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 is omitted.

Embodiment

[0012] [[ID=XX]] [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 drawing is the height direction of the light-emitting device 100. It should be noted that there are some unclear or incorrect parts in the original text, such as the incomplete sentence in line 12. I have tried my best to translate according to the rules. If you have any further questions, please feel free to let me know.

[0013] The light-emitting device 100 includes a substrate 11, a vertical-cavity surface-emitting laser 13 (hereinafter referred to as the surface-emitting laser 13) made of a group-III nitride semiconductor, a light-receiving element 15, a light-transmitting plate 17, and a light reflection structure 19. In FIG. 1, only the outer contour line of the light-transmitting plate 17 is shown by a dashed line to avoid complication of the drawing, and the light reflection structure 19 is hatched. Also, in FIG. 1, the adhesive member AM is omitted.

[0014] [Substrate 11] The substrate 11 is an insulating substrate having a rectangular upper surface shape. The substrate 11 has a rectangular bottom surface in the central region of the upper 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.

[0015] In the light-emitting device 100 of the present embodiment, the substrate 11 is made of a ceramic such as aluminum nitride (AlN). Note that 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.

[0016] [Surface-emitting laser 13] The surface-emitting laser 13 is a VCSEL (Vertical Cavity Surface Emitting Laser) made of a group-III nitride semiconductor that has a rectangular upper surface shape and is mounted on a wiring electrode (not shown) provided on the bottom surface of the recess of the substrate 11.

[0017] The surface-emitting laser 13 is configured to be powered from the outside of the substrate 11 via the above-described wiring electrode, a through electrode (not shown) connected to the wiring electrode and penetrating the bottom of the substrate 11, and a mounting electrode (not shown) connected to the through electrode and provided on the lower surface of the substrate 11. Note that the surface-emitting laser 13 may be mounted on a submount substrate (not shown). That is, a submount substrate may be disposed between the substrate 11 and the surface-emitting laser 13.

[0018] 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.

[0019] 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 of the substrate 11.

[0020] 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).

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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).

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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).

[0050] 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.

[0051] 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.

[0052] 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.

[0053] [Photodetector 15] Refer again to Figures 1 and 2. The light-receiving element 15 has a rectangular top surface shape and is mounted on the bottom surface of the recess of the substrate 11, spaced apart from the surface-emitting laser 13. The light-receiving element 15 is a photodiode (PD) that receives light emitted from the outside and generates an electrical signal corresponding to the intensity of the received light. The light-receiving element 15 is mounted, for example, by a method using surface mounting or wire bonding.

[0054] [Translucent plate 17] The light-transmitting plate 17 is a flat, transparent plate-like body having a rectangular top surface. The light-transmitting plate 17 is bonded to the upper surface of the frame portion that forms the recess of the substrate 11 via an adhesive member AM. In other words, the light-transmitting plate 17 seals the opening of the recess in the substrate 11 so as to enclose the surface-emitting laser 13 and the light-receiving element 15. In the light-emitting device 100 of this embodiment, the light-transmitting plate 17 is made of a material that is transparent to blue light, such as SiO2.

[0055] The light-transmitting plate 17 may also have optical elements on its upper surface, such as a diffractive optical element (DOE) or a holographic optical element (HOE), that control the beam pattern of the laser light.

[0056] [Light reflective structure 19] The light-reflecting structure 19 has a rectangular top surface shape and is a light-reflecting film formed on the lower surface of the light-transmitting plate 17. In the light-emitting device 100 of this embodiment, the light-reflecting structure 19 is formed to cover the area to the right of the area where the surface-emitting laser 13 is located on the bottom surface of the recess of the substrate 11, as shown in Figure 1.

[0057] In the light-emitting device 100 of this embodiment, the light-reflecting structure 19 is made of a metal that has high reflectivity to blue light, such as silver (Ag), Al, and chromium (Cr). The light-reflecting structure 19 is formed, for example, by depositing a metal to be the material of the light-reflecting structure 19 using a sputtering method or a vapor deposition method.

[0058] Furthermore, the light-reflecting structure 19 is formed so as not to obstruct the region of the light-transmitting plate 17 into which the principal light ML emitted from the surface-emitting laser 13 is injected. Specifically, in a top view of the light-emitting device 100, the distance from the central axis CA of the surface-emitting laser 13 to the long side of the light-reflecting structure 19 on the surface-emitting laser 13 side is preferably about 40 μm.

[0059] [Emitted light from surface-emitting laser 13] The light emitted from the surface-emitting laser 13 of the light-emitting device 100 in this embodiment will be described below with reference to Figures 2, 5, and 6. 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 that.

[0060] Because the surface-emitting laser 13 has such a configuration and is a VCSEL made of a group III nitride semiconductor, the inventors of the present invention have newly discovered that the laser light emitted from the surface-emitting laser 13 consists of a principal beam ML (solid line in the figure) emitted along the central axis CA due to resonance in the resonator OC, and a secondary beam SL (dotted line in the figure) 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 a laser beam emitted in a different direction from the principal beam ML and has a different optical axis, and is emitted separately from the principal beam ML.

[0061] The primary light ML and secondary light SL have different optical outputs, but their peak wavelengths are the same. This secondary light SL is the diameter W of the protrusion 27P of the p-type semiconductor layer 27. a The diameter W of the second multilayer reflecting mirror 33 b This is a unique type of light emitted from VCSELs that are smaller than the main VCSEL and made of hexagonal crystal system materials such as group III nitride semiconductors. Therefore, for example, the generation of secondary light SL has not been confirmed in VCSELs made of tetragonal crystal system materials such as gallium arsenide (GaAs) or aluminum indium gallium phosphide (AlInGaP) that emit wavelengths in the red band.

[0062] The secondary light SL is thought to be diffracted light, which is formed when a portion of the light resonating inside the resonator OC is diffracted at a predetermined angle toward the direction outward from the resonator OC and toward the second multilayer reflector 33, and this diffracted light is emitted to the outside.

[0063] More specifically, the secondary light SL is thought to be a portion of the light that reaches a resonant state within the resonator OC, which travels from the p-type semiconductor layer 27 to the insulating layer 29, which has a different refractive index than the p-type semiconductor layer 27, passes through the insulating layer 29, is reflected by the second multilayer reflector 33, and then emitted outside the surface-emitting laser 13 at a predetermined angle with respect to the central axis CA.

[0064] 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 a ring-shaped region surrounding the primary beam ML.

[0065] FIG. 6 is a graph showing the relationship between the output and the emission angle of the light emitted from the surface-emitting laser 13 of the present embodiment. In FIG. 6, the light output for each angle with respect to the central axis CA is shown when the light output near the emission angle 6° of the main light ML of the surface-emitting laser 13 is taken as 1. Although the peak of the light output of the actual main light ML exists at the emission angle 0°, that is, although it is larger than the light output at emission angles other than 0°, here the light output near the emission angle 6° is taken as 1 without being shown in the figure.

[0066] The light emitted from the surface-emitting laser 13 of the present embodiment contains, in addition to the main light ML, a light component having an angle of about 40° with respect to the central axis CA and a light output of about 1% of the peak of the light output of the main light ML. In the surface-emitting laser 13 of the present embodiment, the light component with this angle θ = 40° is emitted as the sub-light SL.

[0067] Among the light transmitted through the protruding portion 27P, the light component along the central axis CA is finally emitted from the surface-emitting laser 13 as the main light ML. On the other hand, the light component having an angle with respect to the central axis CA is partially incident on the second multilayer film mirror 33 and is reflected by the second multilayer film mirror 33.

[0068] At this time, W when the emission wavelength is λ b The light components incident on the second multilayer film mirror 33 at an angle θ that satisfies sinθ = mλ (m is an integer) become light with aligned phases when reflected by the second multilayer film mirror 33.

[0069] As a result, in the surface-emitting laser 13 of the present embodiment, the sub-light SL as laser light is emitted in the direction of the angle θ. In the surface-emitting laser 13 of the present embodiment, the angle θ is approximately 40° as described above.

[0070] Refer again to Figures 1 and 2. In the light-emitting device 100 of this embodiment, the light-reflecting structure 19 is formed to cover a part of the annular region on the lower surface of the light-transmitting plate 17 to which the secondary light SL is irradiated. Therefore, a portion of the secondary light SL emitted from the surface-emitting laser 13 is reflected by the light-reflecting structure 19.

[0071] Furthermore, in the light-emitting device 100 of this embodiment, the light-receiving element 15 is mounted on the bottom surface of the recess of the substrate 11 at a position where it can receive the secondary light SL reflected by the light-reflecting structure 19. As a result, when the light-receiving element 15 receives the secondary light SL, it generates an electrical signal corresponding to the light intensity of the received secondary light SL.

[0072] Therefore, for example, when the light receiving element 15 receives the secondary light SL, if the light intensity of the received secondary light SL falls below a predetermined value, adjustments such as increasing the light output of the surface-emitting laser 13 can be made. In other words, according to the light-emitting device 100 of this embodiment, it is possible to control the light output of the surface-emitting laser 13 by monitoring the light intensity of the secondary light SL. At this time, since the peak of the light output of the secondary light SL has a relationship of approximately 1% with the peak of the light output of the main light ML, it is possible to control the main light ML by monitoring the light intensity of the secondary light SL.

[0073] Therefore, according to the light-emitting device 100 of this embodiment, the light emitted from the surface-emitting laser 13, which is a vertical-cavity type light-emitting element, includes a main light ML and a secondary light SL, and the output of the light emitted from the surface-emitting laser 13 can be controlled by acquiring the light intensity of the secondary light SL via the light-receiving element 15.

[0074] In this embodiment, in order for the secondary light SL to be emitted from the surface-emitting laser 13 in the light source 100, the diameter W of the protrusion 27P of the p-type semiconductor layer 27 is required for light with a peak wavelength of 445 nm. a Preferably, the diameter W of the second multilayer reflecting mirror 33 is less than 10 μm. b It is preferable that the particle size is between 10 μm and 20 μm.

[0075] In the light-emitting device 100 of this embodiment, the light-reflecting structure 19 only needs to be configured to reflect secondary light SL, and does not have to be a metallic reflective film. For example, the light-reflecting structure 19 may consist of a dielectric multilayer film formed by stacking multiple dielectric films.

[0076] 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; it is sufficient if the region where the insulating layer 29 is formed functions as an insulating part.

[0077] The outer region of the p-type semiconductor layer 27, beyond the protrusion 27P on its upper surface, is formed, for example, 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.

[0078] [Examples of applications of the light-emitting device 100] Here, an example of the application of the light-emitting device 100 will be explained using Figure 7. Figure 7 is a block diagram showing the configuration of a light-emitting module 110 related to an example of the application of the light-emitting device 100. The light-emitting module 110 is composed of the light-emitting device 100 described above and an output control unit 40.

[0079] The output control unit 40 is a control device electrically connected to the surface-emitting laser 13 and the photodetector 15 of the light-emitting device 100. The output control unit 40 is, for example, an APC (Automatic Power Control) circuit that automatically adjusts the drive current of the surface-emitting laser 13 so that the optical output of the surface-emitting laser 13 remains constant.

[0080] In the light-emitting module 110 of this embodiment, the output control unit 40 acquires an electrical signal from the photodetector 15 corresponding to the light intensity of the secondary light SL, and adjusts the drive current of the surface-emitting laser 13 based on the acquired electrical signal. This eliminates the need to manually adjust the light output of the surface-emitting laser 13 according to the light intensity of the secondary light SL received by the photodetector 15, for example.

[0081] [Example 1] Next, a modification 1 of the light-emitting device 100 of Example 1 will be described using Figure 8. Figure 8 is a top view of the light-emitting device 100A according to modification 1. The light-emitting device 100A differs from Example 1 in the manner in which the light-reflecting structure 19 is formed, and is otherwise similar to the light-emitting device 100.

[0082] In the modified light-emitting device 100A, the light-reflecting structure 19 has an annular upper surface shape and is formed to cover the entire annular region of the light-transmitting plate 17 into which the secondary light SL is incident. As a result, all of the secondary light SL emitted from the surface-emitting laser 13 is reflected by the light-reflecting structure 19.

[0083] In this modified light-emitting device 100A, this configuration makes it possible to suppress the leakage of the secondary light SL to the outside of the surface-emitting laser 13. In other words, it is possible to prevent light other than the primary light ML from being emitted from the light-emitting device 100A.

[0084] [Differentiation 2] Next, a modification 2 of the light-emitting device 100 of Example 1 will be described using Figure 9. Figure 9 is a top view of the light-emitting device 100B according to modification 2. The light-emitting device 100B differs from Example 1 in the manner in which the light-reflecting structure 19 is formed, and is otherwise similar to the light-emitting device 100.

[0085] In this modified light-emitting device 100B, the light-reflecting structure 19 has a rectangular top surface shape and is formed in four locations on the top, bottom, left, and right sides of the surface-emitting laser 13 when viewed from above. In addition, in this modified light-emitting device 100B, four light-receiving elements 15 are provided on the top, bottom, left, and right sides when viewed from above, so that each can receive the secondary light SL reflected by each of the light-reflecting structures 19.

[0086] In the modified light-emitting device 100B, the intensity of the secondary light SL can be obtained more accurately than, for example, when only one photodetector 15 is used, in order to obtain the light intensity of the secondary light SL from each of the multiple photodetectors 15.

[0087] [Difference 3] Next, a third modification of the light-emitting device 100 of Example 1 will be described using Figure 10. Figure 10 is a top view of the light-emitting device 100C according to the third modification. The light-emitting device 100C differs from Example 1 in that it includes a light-absorbing structure 45, and is otherwise similar to the light-emitting device 100.

[0088] The light-absorbing structure 45 is a light-absorbing film formed in the region of the light-transmitting plate 17 excluding the region into which the principal light ML is injected and the region into which the light-reflecting structure 19 is formed. The light-absorbing structure 45 is formed, for example, by depositing metal nanoparticles or an oxide film having light-absorbing properties onto the light-transmitting plate 17. In particular, metal nanoparticles such as Ag nanoparticles with a particle size of about 100 nm or less can be used, and more preferably, metal nanoparticles with a particle size of about 70 nm can be used to efficiently absorb light in the blue wavelength band.

[0089] In this modified light-emitting device 100C, this configuration allows only the main light ML to be emitted from the light-emitting device 100C. Furthermore, because the light absorption structure 45 can absorb the secondary light SL that does not contribute to light reception within the recess of the substrate 11, a noise reduction effect can be expected, and the intensity of the secondary light SL can be obtained more accurately. [Examples]

[0090] Next, the light-emitting device 200 according to Embodiment 2 will be described with reference to Figure 11. Figure 11 is a cross-sectional view of the light-emitting device 200. The light-emitting device 200 differs from Embodiment 1 in that it has multiple vertical resonator type light-emitting elements, and is otherwise similar to the light-emitting device 100.

[0091] In the light-emitting device 200 of this embodiment, three surface-emitting lasers, surface-emitting laser 13A, surface-emitting laser 13B, and surface-emitting laser 13C, are mounted on the bottom surface of the recess of the substrate 11. In the light-emitting device 200 of this embodiment, surface-emitting laser 13A emits blue light including a primary light ML and a secondary light SL, similar to the first embodiment.

[0092] In the light-emitting device 200 of this embodiment, the surface-emitting laser 13B emits a principal light ML2 having a red wavelength. In addition, in the light-emitting device 200 of this embodiment, the surface-emitting laser 13C emits a principal light ML3 having a green wavelength. Therefore, the light-emitting device 200 of this embodiment emits white light which is a mixture of blue light, red light, and green light.

[0093] In the light-emitting device 200 of this embodiment, the light output of the surface-emitting laser 13A can be adjusted by receiving the secondary light SL emitted from the surface-emitting laser 13A with the light-receiving element 15 and monitoring the light intensity of the received secondary light SL. In addition, the light outputs of the surface-emitting lasers 13B and 13C can also be adjusted in accordance with this adjustment.

[0094] In this embodiment, the light-emitting device 200 may also be capable of emitting secondary light SL from the surface-emitting laser 13C. That is, multiple light-receiving elements 15 may be used to monitor secondary light SL at multiple wavelengths. [Explanation of Symbols]

[0095] 100, 100A, 100B, 100C, 200 Light-emitting devices 11 circuit boards 13. Surface-emitting laser (vertical cavity type light-emitting element) 15. Photodetector 17 Translucent plate 19 Light reflective structure 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 40 Output control unit 45 Light absorption structure NE n electrode PE p electrode

Claims

1. A substrate having a recess, A vertical resonator type light-emitting element made of a group III nitride semiconductor is mounted on the bottom surface of the recess of the substrate, emits laser light toward the opening of the recess, and the laser light includes a primary beam that forms a beam spot and a secondary beam that is emitted in a different direction from the primary beam and has a lower optical output than the primary beam. A light-receiving element mounted on the bottom surface of the recess of the substrate, A light-transmitting plate that closes the opening in the recess, A light-reflecting structure formed in a region of the light-transmitting plate other than the principal light incidence region, which is the region into which the principal light is incident, A light-emitting device characterized by having the following features.

2. The light-emitting device according to claim 1, characterized in that the light-reflecting structure is formed in at least a portion of the region of the light-transmitting plate to which the secondary light is incident.

3. The light-emitting device according to claim 2, characterized in that the light-reflecting structure is formed in an annular shape on the light-transmitting plate so as to surround the principal light incident region.

4. The light-emitting device according to claim 1, characterized in that a light-absorbing film is formed over a region of the light-transmitting plate other than the principal light incidence region and the region where the light-reflecting structure is formed.

5. 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 bottom surface of the recess and the top surface of the second multilayer reflector face each other. The light-emitting device according to any one of claims 1 to 4, 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 in a region inside the outer edge of the second multilayer reflector when viewed from above.

6. The insulating portion has a translucent insulating layer formed in the annular region, The light-emitting device according to claim 5, characterized in that the refractive index of the second semiconductor layer is greater than the refractive index of the insulating layer.

7. It includes multiple vertical cavity type light-emitting elements that emit light of different wavelengths from each other, The light-emitting device according to any one of claims 1 to 4, characterized in that at least one of the plurality of vertical resonator type light-emitting elements emits the secondary light.

8. A substrate having a recess, A vertical resonator type light-emitting element made of a group III nitride semiconductor is mounted on the bottom surface of the recess of the substrate, A light-receiving element mounted on the bottom surface of the recess of the substrate, A light-transmitting plate that closes the opening in the recess, The light-reflecting structure is formed in a region of the light-transmitting plate other than the principal light incident region, which is the region into which the principal light emitted from the vertical resonator type light-emitting element that forms the beam spot is incident. 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 bottom surface of the recess and the top 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.

9. A light-emitting device comprising: a substrate having a recess; a vertical resonator type light-emitting element mounted on the bottom surface of the recess of the substrate, which emits laser light toward the opening of the recess and the laser light includes a primary beam that forms a beam spot and a secondary beam emitted in a different direction from the primary beam and having a lower optical output than the primary beam, a light-receiving element mounted on the bottom surface of the recess of the substrate, a light-transmitting plate that closes the opening of the recess, and a light-reflecting structure formed in a region of the light-transmitting plate other than the primary beam incident region which is the region into which the primary beam is incident; An output control unit is electrically connected to each of the vertical resonator type light-emitting element and the photodetector and is capable of controlling the output of the laser light from the vertical resonator type light-emitting element. Includes, The light-emitting module is characterized in that the output control unit controls the output of the laser light from the vertical resonator type light-emitting element according to the intensity of the light received by the light-receiving element.

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