Laser photosynthesizer

Abstract

The laser light combining device (100) of the present disclosure comprises a first input side optical waveguide (10), a second input side optical waveguide (11), and a third input side optical waveguide (12), each with one end located on the input side, an output side optical waveguide (13) with the other ends joined together, a red laser light source (20), a green laser light source (21), and a blue laser light source (22) respectively arranged on one end side of each input side optical waveguide (10, 11, 12), and a first surface-emitting laser (31) provided on the upper surface side of the first input side optical waveguide (10) and equipped with a photonic crystal that emits red laser light into the first input side optical waveguide (10).

Description

[Technical field]

[0001] The present disclosure relates to laser light combiners. [Background technology]

[0002] In recent years, the metaverse market, which uses technologies such as Virtual Reality (VR) and Augmented Reality (AR) to create virtual spaces that are different from the real world, has grown rapidly, and is expected to see significant market expansion, especially in the gaming sector. Advances in VR / AR technology have made it possible to create immersive virtual spaces, allowing users to act as their own avatars in the virtual space and enjoy interacting with other users and playing games.

[0003] VR / AR device technologies include several components, such as displaying the virtual space using Head Mounted Display (HMD) technology, highly accurate tracking technology that reflects the user's detection on the avatar in the virtual space using motion tracking technology, and low-latency data processing technology. In addition to 3D scanning and environmental mapping as spatial recognition technologies, lasers are used as light sources to project spatial information three-dimensionally into the real world. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020-095417 [Patent Document 2] JP 2009-252958 A [Patent Document 3] JP 2019-168673 A [Non-patent literature]

[0005] [Non-Patent Document 1] Makoto Yukawa, et.al., “638nm Single Lateral Mode Laser Diode for Micro-Projector Application”, ISLC2008 TuC6, pp.73-74, 2008 [Non-Patent Document 2] Kanji Furuta, Ryuichiro Uemura, "Dry Etching Technology for In-Vehicle 3D Sensors", ULVAC Technical Journal, No. 83, pp. 6-10, September 2019 [Non-Patent Document 3] Yang Gao, et.al., “Study on angle detection capability of silicon Waveguide grating copuler”, SPIE 10848, Micro-Optics and MOEMS,1084807 (12 December 2018) [Non-Patent Document 4] Kazuo Kuroda, "Laser Speckle Noise", Laser Research, June 2011, pp.390-394 [Non-Patent Document 5] Wataru Kunishi et al., "Wide temperature range (-40 to 100°C) operation of photonic crystal lasers", Proceedings of the 68th Spring Meeting of the Japan Society of Applied Physics, 18a-Z10-6 [Non-Patent Document 6] Susumu Noda, et.al., “High-power and high-beam-quality photonic-crystal surface-emitting lasers: a tutorial”, Advances in Optics and Photonics Vol.15, Issue 4, pp.977-1032 (2023) [Non-Patent Document 7] Junichi Sakai, "Numerical Analysis of Electromagnetic Fields in Optical Waveguides", Morikita Publishing, 2015, pp.178. Summary of the Invention [Problem to be solved by the invention]

[0006] One of the image display methods used for the above-mentioned applications is to combine the three primary colors of light (red, green, and blue) (RGB lasers) into one to produce white light, and then use this combined light to project the light onto a MEMS (Micro Electro Mechanical Systems). One method is to use a high-speed mirror such as a hologram scanner (HDMS Mechanical Systems) to scan the beam and project the image onto a screen.

[0007] In recent years, an optical integrated circuit technology called silicon photonics, which applies the CMOS (Complementary Metal-Oxide-Semiconductor) process of silicon (Si) semiconductors, has made it possible to create optical designs that are smaller and less expensive than conventional spatial optical systems, and the application of silicon photonics to HMDs and small glasses-type devices is progressing.

[0008] In addition, as described in Patent Document 1, it is expected that new silicon photonics devices that reduce the losses that theoretically occur when laser light of different wavelengths is combined in the combination section of the optical waveguide will be installed in new compact VR / AR equipment.

[0009] However, it is known that the red laser among RGB lasers has a large temperature dependency, and in particular, the optical output drops significantly at high temperatures, as described in Non-Patent Document 1. As devices become smaller, there is no room for heat dissipation in VR / AR devices, and the devices become hot during operations such as graphic processing, so the output of the red laser among the three colors drops, making colors appear darker, and in some cases, problems such as light source failure often occur.

[0010] In addition, silicon photonics has the advantage that the refractive index of the Si core material of the optical waveguide is greater than that of the compound semiconductor that constitutes the light source, so that the light can be tightly confined in the core layer. However, because Si has a large optical absorption, the absorption loss per length of the optical waveguide occurs synergistically with the decrease in optical output of the red laser due to high-temperature operation, causing further problems in the operation of the device.

[0011] As a solution to the above-mentioned problems, for example, Patent Document 2 discloses a laser that uses a gain medium on the InP layer side by providing a resonant structure on one side of a surface-emitting laser made of InP material and stacking a laminated dielectric film on the other side of the resonant structure mounted on a Si substrate.

[0012] Normally, such surface emitting lasers are easy to align with the optical circuit of silicon photonics, but they have a problem that it is difficult to obtain the required optical output due to structural constraints. According to Non-Patent Document 2, a surface emitting laser (Vertical Cavity Surface Emitting Laser: VCSEL) is an edge emitting laser. The optical output of VCSELs is several tens of times smaller than that of electric emitting lasers (EELs). Therefore, to increase the optical output using VCSELs, it is necessary to arrange many VCSELs in an array. However, because chips incorporating optical integrated circuits using silicon photonics are becoming smaller, there is a problem that it is not possible to secure an area to mount a sufficient number of arrayed VCSELs to ensure sufficient optical output.

[0013] Patent Document 3 discloses a method of mounting an EEL on a silicon photonics optical circuit and transferring light from a laser light source to a silicon photonics optical circuit by an optical coupling method using a grating coupler that uses a diffraction grating. However, when optically coupling single-mode light as described in Non-Patent Document 3 using a grating coupler in silicon photonics, the coupling efficiency is about 40%, and the tolerance is narrow at the level of several μm, making it difficult to align the core, resulting in a problem of poor coupling efficiency.

[0014] In particular, when the light source is a multimode light source, the alignment precision becomes even more stringent. For the above reasons, the optical output becomes very small, and this, combined with the fact that the temperature characteristics of the optical output of red lasers deteriorate at high temperatures, poses a practical problem.

[0015] The above describes in detail the decrease in optical output of red lasers when they are operated at high temperatures. In addition to the above problems, when RGB lasers are synthesized and projected onto a screen, a problem unique to lasers called speckle noise can occur, causing the screen to appear visually glaring (Non-Patent Document 4).

[0016] One solution to the speckle noise problem is wavelength multiplexing, which adds laser light sources with slightly shifted oscillation wavelengths. However, due to size restrictions, it can be difficult to add new light sources with different oscillation wavelengths to the light source modules of VR / AR devices, especially glasses-type devices, even as silicon photonics miniaturizes optical integrated circuits.

[0017] The present disclosure has been made to solve the problems described above, and aims to provide a laser light combining device that combines and uses multiple visible light source light sources, and that has stable light output characteristics even when operated at high temperatures. [Means for solving the problem]

[0018] The laser light synthesizer of the present disclosure comprises: A substrate; a first input side optical waveguide formed on the substrate and having one end located on the input side; a second input-side optical waveguide formed on the substrate and having one end located on the input side; a third input-side optical waveguide formed on the substrate and having one end located on the input side; an output-side optical waveguide formed on the substrate, in which the other end of the first input-side optical waveguide, the other end of the second input-side optical waveguide, and the other end of the third input-side optical waveguide are coupled together; a red laser light source disposed on one end side of the first input side optical waveguide and configured to emit a red laser light into the first input side optical waveguide; a green laser light source disposed on one end side of the second input side optical waveguide and configured to emit green laser light into the second input side optical waveguide; a blue laser light source disposed on one end side of the third input side optical waveguide and configured to emit blue laser light into the third input side optical waveguide; a first surface-emitting laser provided on an upper surface side of the first input-side optical waveguide and including a photonic crystal for emitting red laser light into the first input-side optical waveguide; Equipped with. Effect of the Invention

[0019] According to the laser light combining device of the present disclosure, it is possible to obtain a laser light combining device having stable light output characteristics even during operation at high temperatures. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic view of a laser beam combiner according to a first embodiment. [Diagram 2] 1 is a cross-sectional view taken along a light guide direction of a laser beam combining device according to a first embodiment. [Diagram 3] FIG. 2 is a schematic view of a laser light combining device as a comparative example. [Figure 4] FIG. 11 is a schematic view of a laser beam combiner according to a second embodiment. [Diagram 5] FIG. 11 is a schematic view of a laser beam combiner according to a third embodiment. [Figure 6] 11 is a cross-sectional view taken along the light guide direction of a laser beam combiner according to a third embodiment. FIG. [Figure 7] FIG. 11 is a schematic view of a laser beam combiner according to a fourth embodiment. [Figure 8] FIG. 13 is a schematic view of a laser beam combiner according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Embodiment 1 Fig. 1 is a schematic diagram of a laser beam combiner 100 according to embodiment 1. Fig. 2 is a cross-sectional view taken along the light guide direction of a first input side optical waveguide of the laser beam combiner 100 according to embodiment 1.

[0022] <Configuration of the laser beam combiner according to the first embodiment> The laser light combining device 100 according to the first embodiment includes a Si substrate 1, a first input side optical waveguide 10 having one end located on the input side, a second input side optical waveguide 11 having one end located on the input side, a third input side optical waveguide 12 having one end located on the input side, an output side optical waveguide 13 in which the other end of the first input side optical waveguide 10, the other end of the second input side optical waveguide 11, and the other end of the third input side optical waveguide 12 are coupled together, and an output side optical waveguide 13 disposed on one end side of the first input side optical waveguide 10 and connected to the first input side optical waveguide 10. the first input side optical waveguide 10 includes a red laser light source 20 that emits red laser light into the second input side optical waveguide 11, a green laser light source 21 that is arranged on one end side of the second input side optical waveguide 11 and emits green laser light into the second input side optical waveguide 11, a blue laser light source 22 that is arranged on one end side of the third input side optical waveguide 12 and emits blue laser light into the third input side optical waveguide 12, and a first surface-emitting laser 31 that is provided on the upper surface side of the first input side optical waveguide 10 and includes a photonic crystal that emits red laser light into the first input side optical waveguide 10.

[0023] The first input optical waveguide 10, the second input optical waveguide 11, the third input optical waveguide 12, and the output optical waveguide 13 are each formed from a lower cladding layer 2 made of SiO2 from the Si substrate 1 side. The optical waveguide layer 3 is made of Si, and the upper cladding layer 4 is made of SiO2. .

[0024] 2 is a cross-sectional view along the light guiding direction in the first input side optical waveguide 10 of the laser light combining device 100 according to the first embodiment. A first surface-emitting laser 31 equipped with a photonic crystal is disposed on the upper surface side of the first input side optical waveguide 10, i.e., on the upper clad layer 4. The first surface-emitting laser 31 emits red laser light into the first input side optical waveguide 10 via the first optical waveguide 14 formed inside the upper clad layer 4 of the first input side optical waveguide 10.

[0025] The laser beam combiner 100 using silicon photonics according to the first embodiment can be realized by applying a CMOS process for a Si semiconductor. The substrate that serves as the base of the laser beam combiner 100 is a silicon on insulator (SOI) substrate. The SOI substrate is composed of a Si substrate 1 and a SiO2 layer formed on the Si substrate 1. The SiO2 layer having a thickness of about 3 μm located under the optical waveguide layer 3 is called the lower cladding. Since it is used as the guide layer 2, efficient light confinement in the optical waveguide layer 3 made of Si is possible.

[0026] <Method of manufacturing the laser light combining device according to the first embodiment> First, in order to remove impurities and surface unevenness on the SOI substrate, the SOI substrate is cleaned by methods such as reactive ion etching and mechanical polishing. Making the surface of the SOI substrate smooth and uniform reduces the scattering loss of light caused by the effect of surface roughness.

[0027] After cleaning the SOI substrate, the optical waveguide layer 3 is formed using photolithography technology. Photoresist is applied to the surface of the SOI substrate, and then a pattern corresponding to the optical waveguide layer 3 is exposed using a photomask. At this time, the pattern is drawn so that each input side optical waveguide has an appropriate waveguide width and layer thickness. The waveguide width and layer thickness of the optical waveguide layer 3 to be designed will vary depending on whether the laser light source used is single mode or multimode.

[0028] In the first embodiment, a layer thickness of micrometers to submicrometers and a waveguide width of several tens of micrometers to several hundreds of micrometers are patterned by photolithography technology. Then, the Si layer is vertically processed by dry etching using a reactive ion etching device or the like to form the optical waveguide layer 3 made of Si.

[0029] When light is incident from the incident end face direction, the optical waveguide width of the laser light source and the optical waveguide width of the silicon photonics are different. Therefore, when forming the optical waveguide layer 3, a part that converts the spot size of the propagating light can be provided at the tip of the optical waveguide layer to eliminate the gap between the two, thereby improving the coupling efficiency.

[0030] Next, the optical waveguide layer 3 made of Si is embedded with a thick SiO2 layer using a CVD (Chemical Vapor Deposition) device etc. The embedded SiO2 layer functions as the upper cladding layer 4 in the optical waveguide.

[0031] Finally, the laser light combiner 100 is cut to the desired size using a dicing device, completing the laser light combiner portion made of silicon photonics.

[0032] Laser diodes corresponding to each wavelength are used as the laser light sources constituting the fabricated silicon photonics laser light combining device 100. The laser diodes that enter from the incident end face direction have oscillation wavelengths corresponding to red, blue, and green, respectively. The laser diode is an example of a laser light source.

[0033] A red laser light source 20 is arranged at one end located on the input side of the first input side optical waveguide 10, a green laser light source 21 is arranged at one end located on the input side of the second input side optical waveguide 11, and a blue laser light source 22 is arranged at one end located on the input side of the third input side optical waveguide 12. The end located on the input side of each input side optical waveguide is also called the incident end face.

[0034] When optically coupling each input-side optical waveguide and each laser light source, it is necessary to precisely control the position and direction of each laser light source. Therefore, it is preferable to prepare a power meter at the output section of the laser light combining device 100 and finely adjust the mounting position of the optical waveguide while checking the actual optical output. This is because such adjustment allows the light from each laser light source to be coupled to the input-side optical waveguide to the maximum extent possible.

[0035] <First surface emitting laser> The laser light combining apparatus 100 according to the first embodiment is characterized in that a first surface-emitting laser 31 equipped with a photonic crystal is used as a light source that emits light from the front side. Unlike a VCSEL, the first surface-emitting laser 31 is confined in two dimensions, making the manufacturing method somewhat complicated. However, a laser equipped with a photonic crystal, that is, a photonic crystal laser, can be manufactured based on design information disclosed in Non-Patent Document 6 and the like. The manufacturing method and element structure of the first surface-emitting laser 31, which is part of the configuration of the laser light combining apparatus 100 according to the first embodiment, will be described below.

[0036] <First method for manufacturing surface-emitting laser> On a GaAs substrate, crystals are grown in the following order using metal organic vapor phase epitaxy (MOVPE) or molecular beam epitaxy (MBE). The n-type cladding layer, n-type guide layer, i-type active layer, p-type cladding layer, and p-type contact layer are then grown.

[0037] The materials constituting the n-type cladding layer and the p-type cladding layer are AlGaAs, AlGaInP, etc. For the n-type guide layer, it is preferable to use a material such as AlGaAs, which has a refractive index as large as possible and can be easily grown as a crystal on a GaAs substrate.

[0038] The active layer is composed of a periodic GaInP / AlGaInP structure with a thickness of several nm, and the light emitting region corresponding to the oscillation wavelength is crystal-grown. On the active layer, a p-type AlGaInP cladding layer with a thickness sufficient for light confinement and a p-type GaAs contact layer are further crystal-grown in that order.

[0039] In order to operate the first surface-emitting laser 31 as a photonic crystal laser, it is necessary that materials with different refractive indices are arranged two-dimensionally and alternately in the above-mentioned n-type guide layer. For this purpose, after crystal growth up to the n-type guide layer, a fine pattern is formed in the n-type guide layer using photolithography technology so as to have a period of about 1 / 4 of the desired oscillation wavelength, and then new crystal growth is performed so as to fill the processed portion with a material with a different refractive index difference.

[0040] After the above-mentioned element structure is formed by crystal growth, the device part is processed and films are formed, and electrodes are formed by reactive ion etching, CVD, deposition, etc. in the wafer process to produce an element structure capable of operating as a red laser.

[0041] A SiO2 film is formed on the wafer surface by CVD or other methods, and a circular pattern with a diameter of several hundred μm is created. A mask is used to process the wafer. Contacts and electrodes for mounting are formed in the areas covered by the mask, while an insulating film that functions as an anti-reflection film that also acts as a surface protection film to ensure sufficient transmittance for the laser light extracted from the active layer is formed in the circular areas not covered by the mask.

[0042] When mounting the first surface-emitting laser 31 with a photonic crystal on the laser photolithosynthesis device 100 using silicon photonics, if the electrodes formed on the surface side of the laser photolithosynthesis device 100 are used and a recognition pattern is created on the back side, it becomes possible to mount the first surface-emitting laser 31 with a photonic crystal on the surface side using an ordinary die bonding device. Note that during mounting, it is desirable that an electrode pattern for injecting carriers into the first surface-emitting laser 31 is formed on the surface side of the laser photolithosynthesis device 100.

[0043] <Operation of the first surface-emitting laser> The operation of the first surface-emitting laser 31 with a photonic crystal fabricated through the above manufacturing process will be described below. In the following description, the first surface-emitting laser 31 is also simply referred to as a photonic crystal laser.

[0044] As a basic configuration of the photonic crystal laser, in order to form a photonic band structure, two different refractive indices n a , n b are alternately repeated to create an optical resonator with a one-dimensional periodic structure having a period A. In this case, when l is an integer and a is a real number, and when a < A, when the range of the position x is represented by the following formula (1), the refractive index distribution n(x) is represented by the following formula (2).

[0045]

Equation

[0046] On the other hand, when the range of the position x is represented by the following formula (3), the refractive index distribution n(x) is represented by the following formula (4).

[0047]

Equation

[0048] The optical modes allowed by the periodic structure described above can be obtained by solving Maxwell's equations. The photonic bands are calculated by solving the eigenvalue equations, which are Maxwell's equations for each designed laser light source, using the plane wave expansion method. The speed of light is c and the central angular frequency of the photonic band is ω. c , the photonic band gap width is Δω, f a = a / A is the refractive index n a The layer goes around As a percentage of the period, ω c , Δω are expressed by the following equations (5) and (6), respectively. It is shown in (Non-Patent Document 7).

[0049]

number

[0050] From equations (5) and (6), the photonic band gap width Δω is the refractive index difference between the two refractive indices, n a and b The photonic band gap width Δω is an index of the intensity of light confined within the resonator of a photonic crystal laser.

[0051] The greater the difference in refractive index between the two refractive indices, the greater the optical output that can be extracted. The n-type guide layer is made of a crystal material that is lattice-matched to the substrate, and since the refractive index is within the range of 3 to 4, the shape after microfabrication can be created by embedding it with a different material. In addition, if the device is created with a processed shape that leaves air (n=1), the element characteristics will be the best.

[0052] When the above-mentioned device structure is in a forward bias state, that is, when a voltage is applied so that the n electrode side is negative (-) and the p electrode side is positive (+), the carriers consisting of electrons and holes injected from the front and back sides respectively combine and are amplified in the active layer region, and a high-output, high-beam-quality laser light is output from the front side due to the effect of the photonic band formed by the microfabrication of the n-type guide layer. The oscillation wavelength at this time, λL is the bending moment of the active layer material. The refractive index is n eff If the order of Bragg reflection is m, it is expressed by the following equation (7).

[0053]

number

[0054] For example, the oscillation wavelength λ of the red laser light source 20 L 635nm, blue laser light source 22 Oscillation wavelength λ L is 450 nm, and the oscillation wavelength λ of the green laser light source 21 is L The effective refractive index of the active layer, n eff By adjusting the period A of the refractive index distribution, the desired A photonic crystal laser with the desired oscillation wavelength can be obtained.

[0055] <Function of the laser light combining device according to the first embodiment> When the RGB lasers consisting of three colors of laser light, red, green, and blue, are operated, each laser light is guided through the optical waveguide layer 3 made of Si formed by silicon photonics, and white light is generated by combining the three colors of laser light in the output side optical waveguide 13.

[0056] By separately arranging a mirror such as an optical system or MEMS at the external output destination of the laser beam combiner 100, it is possible to scan the output beam and draw a desired image on a screen.

[0057] When each laser light source is operated in single mode, the mutual interference of coherent light causes the laser light to scatter on an object, generating a speckle pattern, which is a random interference pattern. This is called the speckle phenomenon, and since it appears as a bright and dark speckled pattern, it causes image quality degradation as image noise, and also causes discomfort as it appears glaring. There are several methods for reducing this type of speckle noise, but the wavelength multiplexing method, which overlaps light of different wavelengths, is often used.

[0058] However, in the laser light combining device 100 formed using silicon photonics, the chip itself is miniaturized, with the size of the elements being on the order of a few centimeters, so adding an additional optical system in the direction of emission from the end face to overlap the light is difficult, since it is difficult to secure space to place the additional components.

[0059] On the other hand, in the present disclosure, red lasers with emission wavelengths differing from each other by several nm are mounted on the incident direction of the end face, and a first surface-emitting laser 31 using a photonic crystal laser is mounted on the front side, and the two emission wavelengths are shifted by several nm, thereby making it possible to reduce speckle noise by wavelength multiplexing. An example of this wavelength shift of several nm is a wavelength shift in the range of 1 nm to 10 nm.

[0060] Furthermore, the light output of the edge-emitting red laser light source 20 is highly temperature dependent, with the light output decreasing particularly at high temperatures. However, the photonic crystal laser, which is a surface-emitting laser, can compensate for this decrease in light output.

[0061] In the first embodiment, the optical waveguide layer 3 of the laser beam combining device 100 using silicon photonics has been described as an example of an optical waveguide layer made of Si. However, the material constituting the optical waveguide layer 3 may be any material containing Si, and may be, for example, SiO or SiN.

[0062] The materials for the guide layers of a photonic crystal laser can be a combination of materials with different refractive index differences, and similar effects can be obtained by using GaAs, AlGaAs, GaInP, AlGaInP, AlInP, etc., which are lattice-matched to GaAs, as the guide layer materials.

[0063] <Advantages of the First Embodiment> As described above, according to the laser light combining device of the first embodiment, the laser light from each laser light source coupled to each input side optical waveguide at the incident end face is combined into one by the output side optical waveguide, and the first surface-emitting laser equipped with a photonic crystal is provided on the upper surface side of the first input side optical waveguide that guides the red laser light, so that the first surface-emitting laser can compensate for the decrease in the optical output of the red laser light, thereby providing an effect of obtaining a laser light combining device with stable optical output characteristics even during high temperature operation. As shown in Non-Patent Document 5, a surface-emitting laser equipped with a photonic crystal has excellent temperature characteristics of optical output.

[0064] Furthermore, according to another aspect of the laser light combining device of embodiment 1, there is a wavelength shift of several nm between the wavelength of the red laser light emitted by the red laser light source and the wavelength of the red laser light emitted by the first surface-emitting laser, thereby providing the effect of obtaining a laser light combining device with reduced speckle noise.

[0065] Comparative example of embodiment 1. 3 is a schematic diagram showing a comparative example of a laser beam combiner. The laser beam combiner 200 according to the comparative example has an element structure in which the first surface-emitting laser 31 is not provided in the laser beam combiner 100 according to the first embodiment.

[0066] In the laser light combiner 200 according to the comparative example, the red laser light source 20 has a large temperature dependency, and the optical output is significantly reduced at high temperatures in particular. As a result, the output of the red laser light source 20 among the three colors is reduced, making the color appear darker, and in some cases, problems such as the light source breaking down often occur.

[0067] Furthermore, when the laser light sources are synthesized and projected onto a screen, speckle noise may occur, causing the screen to appear visually glaring.

[0068] Embodiment 2 FIG. 4 is a schematic diagram of a laser beam combiner 110 according to the second embodiment.

[0069] <Configuration of laser light combining device according to embodiment 2> The laser light combining device 110 according to the second embodiment includes a Si substrate 1, a first input side optical waveguide 10 having one end located on the input side, a second input side optical waveguide 11 having one end located on the input side, a third input side optical waveguide 12 having one end located on the input side, an output side optical waveguide 13 in which the other end of the first input side optical waveguide 10, the other end of the second input side optical waveguide 11, and the other end of the third input side optical waveguide 12 are coupled together, and the first input side optical waveguide 10 includes a green laser light source 21 arranged at one end of the second input side optical waveguide 11 and emitting green laser light into the second input side optical waveguide 11, a blue laser light source 22 arranged at one end of the third input side optical waveguide 12 and emitting blue laser light into the third input side optical waveguide 12, and a first surface-emitting laser 31 provided on the upper surface of the first input side optical waveguide 10 and equipped with a photonic crystal that emits red laser light into the first input side optical waveguide 10.

[0070] The laser light combining device 110 of embodiment 2 differs from the laser light combining device 100 of embodiment 1 in that a red laser light source is not disposed at one end of the input side of the first input side optical waveguide 10.

[0071] In the laser beam combiner 110 according to the second embodiment, it is not necessary to use one end on the input side of the first input side optical waveguide 10 as an incident end face for laser beams incident from the outside. Therefore, in the laser beam combiner 110 according to the second embodiment, only the first surface-emitting laser 31 equipped with a photonic crystal generates red laser beam.

[0072] In the laser beam combiner 110 according to the second embodiment, similarly to the first embodiment, each laser beam can be independently controlled to operate as the laser beam combiner 110. In the laser beam combiner 110 according to the second embodiment, as shown in FIG.

[0073] <Operation of the laser beam combiner according to the second embodiment> In single-mode end-emitting lasers, the tolerance for optical axis alignment is very narrow, at less than a few μm, so alignment is required while driving the light source. Therefore, alignment takes several minutes per laser light source. In the laser light combiner 110 according to the second embodiment, the number of laser light sources coupled to the incident end face can be reduced, so that the overall optical axis alignment time of the laser light combiner 110 can be reduced, improving work efficiency and thus increasing the production volume of laser light combiners.

[0074] <Advantages of the second embodiment> As described above, according to the laser light combining device of embodiment 2, the number of laser light sources on the incident end face side can be reduced, thereby making it possible to shorten the work time required for optical axis alignment, and since a photonic crystal laser is used as the light source of laser light, it is possible to obtain a laser light combining device with stable light output characteristics even when operated at high temperatures.

[0075] Embodiment 3 Fig. 5 is a schematic view of a laser beam combiner 120 according to embodiment 3. Fig. 6 is a cross-sectional view taken along the light guide direction of a first input side optical waveguide in the laser beam combiner according to embodiment 3.

[0076] <Configuration of laser beam combiner according to the third embodiment> The laser light combining device 120 of the third embodiment has the same configuration as the laser light combining device 110 of the second embodiment, and further comprises a second surface-emitting laser 32 having a photonic crystal that emits red laser light, which is provided adjacent to the first surface-emitting laser 31 on the upper cladding layer 4 of the first input side optical waveguide 10, and emits red laser light into the first input side optical waveguide 10 via a second optical waveguide 15 formed inside the upper cladding layer 4 of the first input side optical waveguide 10.

[0077] That is, in the laser light combining device 120 of embodiment 3, a first surface-emitting laser 31 having a photonic crystal that emits red laser light and a second surface-emitting laser 32 having a photonic crystal that also emits red laser light are provided adjacent to each other on the upper surface side of the first input side optical waveguide 10, and the first surface-emitting laser 31 emits red laser light to the first input side optical waveguide 10 via a first optical waveguide 14 formed inside the upper clad layer 4 of the first input side optical waveguide 10, and the second surface-emitting laser 32 emits red laser light to the first input side optical waveguide 10 via a second optical waveguide 15 formed inside the upper clad layer 4 of the first input side optical waveguide 10.

[0078] By using both the first surface-emitting laser 31 and the second surface-emitting laser 32, each equipped with two photonic crystals, as a source of red laser light, it is possible to stabilize the optical output characteristics of the red laser light even during high-temperature operation.

[0079] In the laser light combining device 120 according to the third embodiment, the wavelength of the red laser light from the first surface-emitting laser 31 and the wavelength of the red laser light from the second surface-emitting laser 32 are set to be shifted by about several nm. This makes it possible to reduce speckle noise by wavelength multiplexing. An example of this wavelength shift of about several nm is a wavelength shift in the range of 1 nm to 10 nm.

[0080] <Advantages of the Third Embodiment> As described above, according to the laser light combining device of embodiment 3, the first surface-emitting laser and the second surface-emitting laser are provided adjacent to each other on the upper surface side of the first input side optical waveguide, and red laser light is supplied by the two lasers, the first surface-emitting laser and the second surface-emitting laser. This makes it possible to reduce the number of laser light sources on the input end face side, thereby shortening the work time required for optical axis alignment, and it is possible to obtain a laser light combining device with stable optical output characteristics even when operated at high temperatures.

[0081] Furthermore, according to another aspect of the laser light combining device of embodiment 3, there is a wavelength shift of several nm between the wavelength of the red laser light emitted by the first surface-emitting laser and the wavelength of the red laser light emitted by the second surface-emitting laser, thereby providing the effect of obtaining a laser light combining device with reduced speckle noise.

[0082] Embodiment 4 FIG. 7 is a schematic diagram of a laser beam combiner 130 according to the fourth embodiment.

[0083] <Configuration of laser beam combiner according to embodiment 4> The laser light combining device 130 according to the fourth embodiment includes a Si substrate 1, a first input side optical waveguide 10 having one end located on the input side, a second input side optical waveguide 11 having one end located on the input side, and a third input side optical waveguide 12 having one end located on the input side, which are formed on the Si substrate 1, an output side optical waveguide 13 in which the other end of the first input side optical waveguide 10, the other end of the second input side optical waveguide 11, and the other end of the third input side optical waveguide 12 are coupled together, a red laser light source 20 arranged on one end side of the first input side optical waveguide 10 and emitting red laser light into the first input side optical waveguide 10, and a green laser light source 20 arranged on one end side of the second input side optical waveguide 11 and emitting green laser light into the second input side optical waveguide 11. the third input side optical waveguide 12 includes a laser light source 21, a blue laser light source 22 arranged on one end side of the third input side optical waveguide 12 and emitting blue laser light into the third input side optical waveguide 12, a first surface-emitting laser 31 arranged on the upper surface side of the first input side optical waveguide 10 and equipped with a photonic crystal for emitting red laser light into the first input side optical waveguide 10, a third surface-emitting laser 33 arranged on the upper surface side of the second input side optical waveguide 11 and equipped with a photonic crystal for emitting green laser light into the second input side optical waveguide 11, and a fourth surface-emitting laser 34 arranged on the upper surface side of the third input side optical waveguide 12 and equipped with a photonic crystal for emitting blue laser light into the third input side optical waveguide 12.

[0084] That is, the laser light combining device 130 of embodiment 4 includes, in addition to the configuration of the laser light combining device 100 of embodiment 1, a third surface-emitting laser 33 provided on the upper surface side of the second input side optical waveguide 11, and a fourth surface-emitting laser 34 provided on the upper surface side of the third input side optical waveguide 12.

[0085] The first surface-emitting laser 31 emits red laser light into the first input side optical waveguide 10 via the first optical waveguide 14 formed in the upper cladding layer 4 of the first input side optical waveguide 10. The third surface-emitting laser 33 emits green laser light into the second input side optical waveguide via the third optical waveguide 16 formed in the upper cladding layer 4 of the second input side optical waveguide 11. The fourth surface-emitting laser 34 emits blue laser light into the third input side optical waveguide 12 via the fourth optical waveguide 17 formed in the upper cladding layer 4 of the third input side optical waveguide 12.

[0086] There is a wavelength shift of several nm between the wavelength of the red laser light from the red laser light source 20 and the wavelength of the red laser light from the first surface-emitting laser 31, there is a wavelength shift of several nm between the wavelength of the green laser light from the green laser light source 21 and the wavelength of the green laser light from the third surface-emitting laser 33, and there is a wavelength shift of several nm between the wavelength of the blue laser light from the blue laser light source 22 and the wavelength of the blue laser light from the fourth surface-emitting laser 34.

[0087] <Function of the laser light combining device according to the fourth embodiment> A color gamut is a subset of colors when viewing videos and photos on a screen, and is represented by the RGB colors that are typically used on computer monitors. In reality, the chromaticity that humans can perceive is defined by the CIE 1931 chromaticity diagram, and humans are particularly good at perceiving green. In addition to the effect of widening the color gamut of the three primary colors, RGB, by using light sources with different oscillation wavelengths, RGB light sources, the speckle noise is reduced and the optical output characteristics are stable even during high-temperature operation by using both edge-emitting and surface-emitting lasers, as in the first embodiment.

[0088] <Advantages of the Fourth Embodiment> As described above, according to the laser light combining device of embodiment 4, since laser light of multiple oscillation wavelengths is used, it is possible to expand the color gamut. Furthermore, by superimposing different wavelengths in each laser light, it is possible to reduce speckle noise, and it is possible to obtain a laser light combining device with stable light output characteristics even when operated at high temperatures.

[0089] Embodiment 5. FIG. 8 is a schematic diagram of a laser beam combiner 140 according to the fifth embodiment.

[0090] <Configuration of a laser beam combiner according to the fifth embodiment> A laser beam combining device 140 according to the fifth embodiment includes a Si substrate 1, a first input side optical waveguide 10 having one end located on the input side, a second input side optical waveguide 11 having one end located on the input side, a third input side optical waveguide 12 having one end located on the input side, an output side optical waveguide 13 in which the other end of the first input side optical waveguide 10, the other end of the second input side optical waveguide 11, and the other end of the third input side optical waveguide 12 are coupled together, and an output side optical waveguide 13 disposed on one end side of the first input side optical waveguide 10 and emitting red laser light into the first input side optical waveguide 10. a red laser light source 20 arranged on one end side of the second input side optical waveguide 11 and emitting green laser light into the second input side optical waveguide 11; a blue laser light source 22 arranged on one end side of the third input side optical waveguide 12 and emitting blue laser light into the third input side optical waveguide 12; and a fifth surface-emitting laser 35 provided on the upper surface side of the output side optical waveguide 13 and equipped with a photonic crystal that emits any one of red laser light, green laser light, and blue laser light into the output side optical waveguide 13.

[0091] The fifth surface-emitting laser 35 emits one of red laser light, green laser light, and blue laser light into the output-side optical waveguide 13 via the fifth optical waveguide 18 formed inside the upper cladding layer 4 of the output-side optical waveguide 13.

[0092] <Operation of the laser beam combiner according to the fifth embodiment> The laser light combining device 140 of embodiment 5 is capable of performing operations similar to those of the laser light combining device 100 of embodiment 1 by providing each laser light source arranged on the incident end face side and a fifth surface-emitting laser 35, which is a photonic crystal laser that serves as a light source of a different wavelength from each laser light source, on the upper surface side of the output side optical waveguide 13 and independently controlling each laser light source.

[0093] <Function of the laser light combiner according to the fifth embodiment> When the laser light combiner is used as a light source for VR / AR applications, in the area where the three-color single-mode end-emission RGB lasers are combined, half of the light is guided through the optical waveguide due to the theoretical mode competition between the zeroth and first-order light, while the other half becomes a radiation mode and propagates outside the optical waveguide. Of this, the radiation light radiated outside the optical waveguide no longer returns to the optical waveguide, so the radiation light to the outside of the optical waveguide is purely lost. Therefore, by mounting the laser light combiner 140 on the upper surface side of the output-side optical waveguide 13, which is the emission end surface side of the area where the RGB lasers are combined, it is possible to reduce the loss of light that occurs during combination.

[0094] <Advantages of the Fifth Embodiment> As described above, according to the laser light combining device of embodiment 5, it is possible to suppress speckle noise by superimposing different wavelengths, and it is possible to obtain a laser light combining device that has stable light output characteristics even when operated at high temperatures, and further, is capable of reducing the loss of light that occurs during combining.

[0095] Although the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations.

[0096] Therefore, countless modifications not illustrated are conceivable within the scope of the technology of the present disclosure, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment. [Explanation of symbols]

[0097] REFERENCE SIGNS LIST 1 Si substrate, 2 lower cladding layer, 3 optical waveguide layer, 4 upper cladding layer, 10 first input side optical waveguide, 11 second input side optical waveguide, 12 third input side optical waveguide, 13 output side optical waveguide, 14 first optical waveguide, 15 second optical waveguide, 16 third optical waveguide, 17 fourth optical waveguide, 18 fifth optical waveguide, 20 red laser light source, 21 green laser light source, 22 blue laser light source, 31 first surface emitting laser, 32 second surface emitting laser, 33 third surface emitting laser, 34 fourth surface emitting laser, 35 fifth surface emitting laser, 100, 110, 120, 130, 140, 200 laser light combining device

Claims

1. circuit board and A first input-side optical waveguide is formed on the substrate, with one end located on the input side, A second input-side optical waveguide is formed on the substrate, with one end located on the input side, A third input-side optical waveguide is formed on the substrate, with one end located on the input side, An output optical waveguide is formed on the substrate, in which the other end of the first input optical waveguide, the other end of the second input optical waveguide, and the other end of the third input optical waveguide are coupled together. A red laser light source is positioned at one end of the first input side optical waveguide and emits red laser light into the first input side optical waveguide, A green laser light source is provided, which is located at one end of the second input side optical waveguide and emits green laser light into the second input side optical waveguide. A blue laser light source is provided, which is located at one end of the third input side optical waveguide and emits blue laser light into the third input side optical waveguide. A first surface-emitting laser is provided on the upper surface side of the first input-side optical waveguide and includes a photonic crystal that emits red laser light into the first input-side optical waveguide, A laser photosynthesis device equipped with [a specific feature].

2. The laser photosynthesis apparatus according to claim 1, characterized in that there is a wavelength difference of 1 nm or more and 10 nm or less between the wavelength of the red laser light emitted by the red laser light source and the wavelength of the red laser light emitted by the first surface-emitting laser.

3. circuit board and A first input-side optical waveguide formed on the substrate, A second input-side optical waveguide is formed on the substrate, with one end located on the input side, A third input-side optical waveguide is formed on the substrate, with one end located on the input side, An output optical waveguide is formed on the substrate, in which the other end of the first input optical waveguide, the other end of the second input optical waveguide, and the other end of the third input optical waveguide are coupled together. A green laser light source is provided, which is located at one end of the second input side optical waveguide and emits green laser light into the second input side optical waveguide. A blue laser light source is provided, which is located at one end of the third input side optical waveguide and emits blue laser light into the third input side optical waveguide. A first surface-emitting laser is provided on the upper surface side of the first input-side optical waveguide and includes a photonic crystal that emits red laser light into the first input-side optical waveguide, A laser photosynthesis device equipped with [a specific feature].

4. The laser photosynthesis apparatus according to any one of claims 1 to 3, characterized in that the first input optical waveguide, the second input optical waveguide, the third input optical waveguide, and the output optical waveguide each consist of a lower cladding layer, an optical waveguide layer, and an upper cladding layer, from the substrate side.

5. The laser photosynthesis apparatus according to claim 4, characterized in that the first surface-emitting laser is provided on the upper cladding layer of the first input-side optical waveguide, and the red laser light is emitted into the first input-side optical waveguide via a first optical waveguide formed inside the upper cladding layer of the first input-side optical waveguide.

6. The laser photosynthesis apparatus according to claim 5, characterized in that a second surface-emitting laser equipped with a photonic crystal that emits red laser light is provided adjacent to the first surface-emitting laser on the upper cladding layer of the first input-side optical waveguide, and the red laser light is emitted into the first input-side optical waveguide via a second optical waveguide formed inside the upper cladding layer of the first input-side optical waveguide.

7. The laser photosynthesis apparatus according to claim 6, characterized in that the wavelength of the red laser light emitted by the first surface-emitting laser and the wavelength of the red laser light emitted by the second surface-emitting laser have a wavelength difference of 1 nm to 10 nm.

8. The laser photosynthesis apparatus according to claim 5, further comprising a third surface-emitting laser equipped with a photonic crystal that is provided on the upper surface side of the second input optical waveguide and emits green laser light into the second input optical waveguide via a third optical waveguide formed inside the upper cladding layer of the second input optical waveguide.

9. The laser photosynthesis apparatus according to claim 5, further comprising a fourth surface-emitting laser equipped with a photonic crystal that is provided on the upper surface side of the third input-side optical waveguide and emits blue laser light into the third input-side optical waveguide via a fourth optical waveguide formed inside the upper cladding layer of the third input-side optical waveguide.

10. circuit board and A first input-side optical waveguide is formed on the substrate, with one end located on the input side, A second input-side optical waveguide is formed on the substrate, with one end located on the input side, A third input-side optical waveguide is formed on the substrate, with one end located on the input side, An output optical waveguide is formed on the substrate, in which the other end of the first input optical waveguide, the other end of the second input optical waveguide, and the other end of the third input optical waveguide are coupled together. A red laser light source is provided at one end of the first input-side optical waveguide and emits red laser light into the first input-side optical waveguide, A green laser light source is provided at one end of the second input-side optical waveguide and emits green laser light into the second input-side optical waveguide, A blue laser light source is provided at one end of the third input side optical waveguide and emits blue laser light into the third input side optical waveguide, A fifth surface-emitting laser is provided on the upper side of the output-side optical waveguide and includes a photonic crystal that emits one of the following into the output-side optical waveguide: red laser light, green laser light, and blue laser light. A laser photosynthesis device equipped with [a specific feature].

11. The laser photosynthesis apparatus according to claim 10, characterized in that the first input optical waveguide, the second input optical waveguide, the third input optical waveguide, and the output optical waveguide each consist of a lower cladding layer, an optical waveguide layer, and an upper cladding layer, starting from the substrate side.

12. The laser photosynthesis apparatus according to claim 11, characterized in that the fifth surface-emitting laser is provided on the upper cladding layer of the output-side optical waveguide and emits one of the red laser light, the green laser light, and the blue laser light into the output-side optical waveguide via the fifth optical waveguide formed inside the upper cladding layer of the output-side optical waveguide.

13. The laser photosynthesis apparatus according to any one of claims 1 to 3, 10 to 12, characterized in that the substrate is a silicon substrate.

14. The laser photosynthesis apparatus according to claim 4, characterized in that the lower cladding layer, optical waveguide layer, and upper cladding layer are made of a silicon-containing material.

15. The laser photosynthesis apparatus according to claim 11 or 12, characterized in that the lower cladding layer, the optical waveguide layer, and the upper cladding layer are made of a silicon-containing material.

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