Optical multiplexer, optical multiplexing member, optical multiplexing member with light modulation function, visible light source module, optical engine, and XR glasses

Abstract

The invention provides an optical multiplexer, an optical multiplexing member, an optical multiplexing member with an optical modulation function, a visible light source module, an optical engine, and XR glasses which can be reduced in size and reduced in optical loss compared with the prior art. An optical multiplexer (100) is provided with: an MMI-coupled optical multiplexer unit (50) in which a first MMI-type optical multiplexer unit and a second MMI-type optical multiplexer unit having a narrower width than the first MMI-type optical multiplexer unit are coupled; two optical input-side optical waveguides connected to the first MMI-type optical multiplexer unit; and one optical output-side optical waveguide connected to the second MMI-type optical multiplexer unit. One optical input side optical waveguide is a two-color propagation optical input side optical waveguide for propagating a combined laser beam comprising two laser beams having different wavelengths, and the other optical input side optical waveguide is a single-color propagation optical input side optical waveguide for propagating one laser beam having a wavelength different from that of the two different laser beams. The second MMI-type optical multiplexer is disposed on an extension line of the monochromatic propagation light input-side optical waveguide.

Description

Technical Field

[0001] The present invention relates to an optical combiner, an optical combiner component, an optical combiner component with a light modulation function, a visible light source module, an optical engine and XR glasses. Background Art

[0002] Currently, glasses-type terminals are being studied in VR or AR. In particular, in recent years, retinal scanning displays that enable users to recognize images by imaging two-dimensionally scanned light on the user's retina have attracted much attention. In retinal scanning displays, three-color visible light emitted from light sources such as LEDs (Light Emitting Diodes) or LDs (Laser Diodes) corresponding to the various colors of R (red), G (green), and B (blue) are usually combined on one optical axis. The combined three-color visible light is transmitted to the image display unit. The image display unit performs two-dimensional scanning on the transmitted light and makes it incident on the user's pupil. The incident light forms an image on the user's retina, and the user recognizes the image.

[0003] For example, Patent Document 1 discloses a structure of a retinal projection display using a Mach-Zehnder light modulator.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6728596

[0007] Patent Document 2: Japanese Patent No. 6787397

[0008] Patent Document 3: Japanese Patent No. 6572377

[0009] Patent Document 4: Japanese Patent Application Laid-Open No. 2012-48071

[0010] Patent Document 5: Japanese Patent Application Laid-Open No. 2020-27170 Summary of the Invention

[0011] In the retinal projection display disclosed in Patent Document 1, a plurality of optical waveguides are close to each other in the emission section but are not combined. Therefore, the optical axis differs for each wavelength, making the control of the emitted light complicated.

[0012] In addition, there is a demand for an optical combiner that can be connected to or integrated with a visible light modulator and can adjust the color balance of RGB, but this has not been studied at all.

[0013] However, in Patent Document 1, the light is only brought close to each other without being combined in the emission section. Therefore, the optical axis differs for each wavelength, making the control of the emitted light complicated.

[0014] In addition, a visible light modulator using a lithium niobate film is disclosed in Patent Document 2. An RGB optical multiplexer that can be connected to or integrated with a visible light modulator using a lithium niobate film is desired, but has not yet been studied.

[0015] Directional couplers are generally studied for combining visible light (see, for example, Patent Document 3). These are made of glass-based materials and have excellent stability, but when using a lithium niobate substrate with a large Δn, the coupling length becomes long, making miniaturization impossible.

[0016] Patent Document 4 or Patent Document 5 discloses a structure of an RGB combiner using MMI (Multi-Mode Interferometer), but both use glass-based materials and do not disclose a structure using a lithium niobate film.

[0017] The MMI type optical multiplexer uses multiple waveguide ports to input multiple input signals to the optical input side, and uses a single waveguide port for the output signal on the optical output side to combine all input signals and output them as an output signal.

[0018] The MMI type optical combiner utilizes the characteristic that many modes generated within the optical combiner with a wide width for each wavelength interfere with each other and form an image (focus) at a specific position.

[0019] The present disclosure is proposed in view of the above-mentioned problems, and its purpose is to provide an optical combiner, an optical combining component, a visible light source module and an optical engine that can be connected to or integrated with an optical modulator using a lithium niobate film, and can be more compact and have lower optical loss than before.

[0020] In order to solve the above problems, the present disclosure provides the following technical solutions.

[0021] Method 1 of the present disclosure is an optical combiner that combines multiple lasers of different wavelengths, and comprises: an MMI-coupled optical combining section, which is formed by coupling a first MMI-type optical combining section and a second MMI-type optical combining section having a width narrower than that of the first MMI-type optical combining section from the input side; two optical input-side optical waveguides connected to the first MMI-type optical combining section; and an optical output-side optical waveguide connected to the second MMI-type optical combining section, wherein one of the two optical input-side optical waveguides is a two-color propagation optical input-side optical waveguide for propagating a combined laser composed of two lasers of different wavelengths, and the other optical input-side optical waveguide is a monochromatic propagation optical input-side optical waveguide for propagating a laser different from the two lasers, and the second MMI-type optical combining section is arranged on an extension line of the monochromatic propagation optical input-side optical waveguide.

[0022] A second aspect of the present disclosure is the optical multiplexer of the first aspect, wherein a width of the second MMI-type optical multiplexing section is not less than 1 / 3 and not more than 2 / 3 of a width of the first MMI-type optical multiplexing section.

[0023] A third aspect of the present disclosure is the optical multiplexer according to any one of the first and second aspects, wherein the length of the second MMI-type optical multiplexing section is 10 μm or longer.

[0024] A fourth aspect of the present disclosure is the optical multiplexer according to any one of aspects 1 to 3, wherein the two light input side optical waveguides and the one light output side optical waveguide each have a tapered portion whose width gradually widens toward the MMI coupling type optical multiplexing portion.

[0025] Mode 5 of the present disclosure is an optical combiner of any one of modes 1 to 4, comprising: a pre-MMI type optical combining section, which is arranged on the input side of the MMI coupling type optical combining section; two pre-input side optical waveguides, which are connected to the pre-MMI type optical combining section; and one pre-output side optical waveguide, which is connected to the pre-MMI type optical combining section, and the pre-output side optical waveguide is connected to the optical input side optical waveguide for two-color propagation.

[0026] A sixth aspect of the present disclosure is the optical multiplexer according to any one of aspects 1 to 5, wherein all of the plurality of different wavelengths are visible light wavelengths.

[0027] A seventh aspect of the present disclosure is an optical multiplexing component comprising: a substrate made of a material different from lithium niobate; and a lithium niobate film formed on a main surface of the substrate, wherein the optical multiplexer according to any one of aspects 1 to 6 is formed on the lithium niobate film.

[0028] An eighth aspect of the present disclosure is a visible light source module including the optical combining element of the seventh aspect and a plurality of visible light laser light sources that emit visible light combined by the optical combining element.

[0029] Mode 9 of the present disclosure is an optical combining component with an optical modulation function, which includes the optical combining component of Mode 7 and a Mach-Zehnder optical modulator, which is connected to the optical combining component and guides multiple visible lights emitted from multiple visible light laser light sources to the optical combiner.

[0030] Method 10 of the present disclosure is a visible light source module, which has an optical combining component with light modulation function of method 9, and multiple visible light laser light sources that emit visible light combined by the optical combining component with light modulation function, and the multiple visible light laser light sources are visible light laser light sources of red light, green light, and blue light.

[0031] Aspect 11 of the present disclosure is an optical engine including: the visible light source module of aspect 8; and a light scanning mirror configured to change the angle of light emitted from the visible light source module and reflect the light so as to display an image.

[0032] Aspect 12 of the present disclosure is an optical engine including: the visible light source module of aspect 10; and a light scanning mirror configured to change the angle of light emitted from the visible light source module and reflect the light so as to display an image.

[0033] A thirteenth embodiment of the present disclosure is an XR glasses equipped with the optical engine of the eleventh embodiment.

[0034] A fourth aspect of the present disclosure is an XR glasses equipped with the optical engine of the twelfth aspect.

[0035] According to the present invention, an optical multiplexer can be provided that can be connected to or integrated with an optical modulator using a lithium niobate film, and that can be more compact and have lower optical loss than conventional optical multiplexers. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic plan view showing an example of the optical multiplexer of the present disclosure.

[0037] Figure 2 FIG. 1 is a schematic plan view showing another example of the optical multiplexer disclosed in the present invention.

[0038] Figure 3 FIG. 1 is a schematic plan view showing another example of the optical multiplexer disclosed in the present invention.

[0039] Figure 4A This figure is used to explain the principle of the MMI type optical combiner and shows the width W of the optical combiner. M A conceptual diagram showing the relationship between the effective width We and single mode and higher-order modes.

[0040] Figure 4BThis diagram explains the principle of an MMI-type optical multiplexer and shows simulation results of electromagnetic field distributions in waveguide cross sections for each of a single mode (TMO), a higher-order mode (TM1), and a higher-order mode (TM2).

[0041] Figure 5A This is a diagram for explaining the principle of an MMI-type optical multiplexer, and shows the results of a simulation of the electromagnetic field distribution of red (R) light.

[0042] Figure 5B This is a diagram for explaining the principle of the MMI-type optical multiplexer, and shows the results of a simulation of the electromagnetic field distribution of green (G) light.

[0043] Figure 6A Graphs are provided showing the relationship between the length and beat length of the first and second MMI-type optical multiplexing devices and the output intensity for red (R) laser light.

[0044] Figure 6B Graphs are provided showing the relationship between the length and beat length of the first and second MMI-type optical multiplexing devices and the output intensity for green (G) laser light.

[0045] Figure 7 Schematic top view of the optical combining component of the present invention.

[0046] Figure 8 yes Figure 7 The schematic cross-sectional view of the optical combining component shown is taken along line XX'.

[0047] Figure 9 This is a schematic cross-sectional view taken along the YZ plane when the cross section of the MMI-type optical multiplexing section is trapezoidal in shape and has a flat plate portion on the substrate side.

[0048] Figure 10 It is a schematic top view of the optical multiplexing component with light modulation function disclosed in the present invention.

[0049] Figure 11 2 is a schematic top view of the visible light source module disclosed in the present invention.

[0050] Figure 12 Cut by XZ plane Figure 11 The schematic cross-sectional view of the light source module shown depicts only a portion near the joining portion.

[0051] Figure 13A This is a diagram for explaining an example of a method for driving a light modulator.

[0052] Figure 13B This is a diagram for explaining another example of a method for driving a light modulator.

[0053] Figure 13C This is a diagram for explaining another example of a method for driving a light modulator.

[0054] Figure 14 2 is a schematic top view of the visible light source module disclosed in the present invention.

[0055] Figure 15 This is a conceptual diagram for explaining an example of the XR glasses of the present invention.

[0056] Figure 16 It means in Figure 15 A conceptual diagram of the XR glasses showing how laser light emitted from a light source module directly projects an image onto the retina.

[0057] Figure 17 This is a diagram showing the parameters of the model used in the simulation.

[0058] Figure 18A This is a graph of Example 1. The horizontal axis represents the length L1 of the first MMI-type optical multiplexing device, and the vertical axis represents the light intensity loss after each RGB wavelength passes through the MMI-connected optical multiplexing section.

[0059] Figure 18B This is a graph of Comparative Example 1, where the horizontal axis represents the length L1 of the first MMI-type optical multiplexing device, and the vertical axis represents the light intensity loss after each RGB wavelength passes through the MMI-connected optical multiplexing section.

[0060] Explanation of symbols

[0061] 10 substrates

[0062] 20Photosynthesis functional layer

[0063] 24 lithium niobate film

[0064] 30 visible light laser light source

[0065] 40 Mach-Zehnder optical modulator

[0066] 50MMI coupling type optical multiplexing unit (MMI type optical multiplexing unit)

[0067] 50-1 The first MMI optical multiplexing device

[0068] 50-2 Second MMI type optical multiplexing device

[0069] 100, 101, 102 optical combiners

[0070] 150MMI single optical multiplexing unit (MMI type optical multiplexing unit)

[0071] 200 optical multiplexing components

[0072] 300 optical multiplexing components with optical modulation function

[0073] 1000, 2000 visible light source modules

[0074] 10000XR glasses. DETAILED DESCRIPTION

[0075] The present disclosure will be described in detail below with reference to the accompanying drawings as appropriate. In the drawings used in the following description, for ease of understanding, portions of the features may be enlarged for the sake of convenience, and the dimensional ratios of the various components may differ from actual dimensions. The materials, dimensions, and other aspects illustrated in the following description are merely examples, and the present disclosure is not limited thereto. Appropriate modifications and implementations may be made within the scope of achieving the effects of the present disclosure.

[0076] 〔Photosynthesis Device〕

[0077] Figure 1 1 is a schematic top view of an example of the optical combiner disclosed herein. Figure 2 FIG. 1 is a schematic plan view showing another example of the optical multiplexer disclosed in the present invention.

[0078] The optical combiner disclosed in the present invention is a multi-mode interference (MMI) type optical combiner.

[0079] In this manual, sometimes Figure 1 The optical combining section formed by coupling parts of different sizes (rectangular parts when viewed from above) is called an "MMI-coupled optical combining section". The parts (rectangular parts when viewed from above) that constitute the MMI-coupled optical combining section are called "optical combining devices". In contrast, an optical combining section composed of a single rectangular part is sometimes called an "MMI-single-type optical combining section". An MMI-single-type optical combining section is composed of a single optical combining device. The MMI-coupled optical combining section and the MMI-single-type optical combining section are sometimes collectively referred to as an MMI-type optical combining section.

[0080] Furthermore, an optical multiplexing section in which MMI single-type optical multiplexing sections or MMI coupled-type optical multiplexing sections are connected via an optical waveguide is sometimes referred to as an "MMI-connected optical multiplexing section." Furthermore, depending on the number of optical waveguides, a structure in which two connected MMI single-type optical multiplexing sections or MMI coupled-type optical multiplexing sections are connected is sometimes referred to as a two-segment MMI-connected optical multiplexing section (or simply a two-segment MMI-type optical multiplexing section), a structure in which three are connected is sometimes referred to as a three-segment connected-type optical multiplexing section (or simply a three-segment MMI-type optical multiplexing section), and a structure in which multiple sections are connected is sometimes referred to as a multi-segment connected-type optical multiplexing section (or simply a multi-segment MMI-type optical multiplexing section). Unconnected structures are sometimes referred to as a single-segment MMI single-type optical multiplexing section or a single-segment MMI coupled-type optical multiplexing section. Sometimes, one segment of the MMI single-type optical multiplexing section and one segment of the MMI coupled-type optical multiplexing section are collectively referred to as one segment of the MMI optical multiplexing section.

[0081] Figure 1 The optical combiner 100 shown is an optical combiner for combining a plurality of laser beams of different wavelengths, and comprises: an MMI-coupled optical combiner 50, which is formed by coupling a first MMI-type optical combiner (first MMI-type optical combiner device) 50-1 and a second MMI-type optical combiner (second MMI-type optical combiner device) 50-2 having a width W2 narrower than the width W1 of the first MMI-type optical combiner 50-1 from the input side; two optical waveguides 21-1 and 21-2 on the optical input side, which are connected to the first MMI-type optical combiner 50-1; And an optical output side optical waveguide 22, which is connected to the second MMI type optical combining unit 50-2. Among the two optical input side optical waveguides 21-1 and 21-2, one optical input side optical waveguide is a two-color propagation optical input side optical waveguide 21-1 for propagating a combined laser composed of two lasers with different wavelengths, and the other optical input side optical waveguide is a monochromatic propagation optical input side optical waveguide 21-2 for propagating a laser with a wavelength different from that of the two lasers. The second MMI type optical combining unit 50-2 is arranged on the extension line of the monochromatic propagation optical input side optical waveguide 21-2.

[0082] The optical multiplexer 100 is a 2×1 type (two input ports and one output port) optical multiplexer including two light incident ports (a first light incident port 21 - 1 i and a second light incident port 21 - 2 i ) and one light output port 22To.

[0083] exist Figure 1 In FIG. 1 , the X direction is the direction in which the optical waveguide on the light input side extends, the Y direction is a direction perpendicular to the X direction, and the Z direction is a direction perpendicular to a plane formed by the X and Y directions.

[0084] By configuring the 2×1 MMI-coupled optical multiplexing section 50 to couple optical multiplexing devices in a stepwise manner, it is possible to improve the margin of multiplexing loss with respect to the length of the optical multiplexing devices, as described in detail below.

[0085] exist Figure 1 In the illustrated optical multiplexer 100, in the case of an optical multiplexer for multiplexing visible light (RGB) laser beams into multiple different wavelengths, the two laser beams propagating through the dual-color transmission light input-side optical waveguide 21-1 are designated as R (red) and B (blue), and the two laser beams propagating through the monochromatic transmission light input-side optical waveguide 21-2 are designated as G (green). However, this combination is merely an example and is not limited to this combination. Combinations of RB and G, or BG and R, are also possible.

[0086] In addition, the plurality of different wavelengths are not limited to RGB of visible light.

[0087] The width W2 of the second MMI-type optical multiplexing section 50 - 2 is preferably not less than 1 / 3 and not more than 2 / 3 of the width W1 of the first MMI-type optical multiplexing section 50 - 1 .

[0088] The length L2 of the second MMI-type optical multiplexing unit 50 - 2 is preferably not less than 10 μm. The upper limit of the length of the second MMI-type optical multiplexing unit 50 - 2 can be set to, for example, 10 to 200 μm.

[0089] The width W1 of the first MMI-type optical multiplexing unit 50 - 1 can be set to, for example, 3 to 10 μm.

[0090] The second MMI-type optical combining section 50-2 is arranged on the extension line of the optical waveguide 21-2 on the input side for monochromatic propagation light, which means that the imaginary line CC' passing through the center of the width direction of the optical waveguide 21-2 on the input side for monochromatic propagation light overlaps with the imaginary line passing through the center of the width direction of the second MMI-type optical combining section 50-2, or overlaps with the imaginary line CC' passing through the center of the width direction of the optical waveguide 21-2 on the input side for monochromatic propagation light with a deviation smaller than 1 / 3 of the width W2 of the second MMI-type optical combining section 50-2 (see Figure 2 ).

[0091] exist Figure 1 In the optical combiner 100 shown, the two optical input side optical waveguides 21-1 and 21-2 have tapered portions 51-1 and 51-2 in which the width continuously widens as the portion connected to the first MMI-type optical combiner 50-1 approaches the first MMI-type optical combiner 50-1, and the tapered shape of the tapered portion with an inclination angle can be defined. In addition, the one optical output side optical waveguide 22 has a tapered portion 52 in which the width continuously widens as the portion connected to the first MMI-type optical combiner 50-1 approaches the second MMI-type optical combiner 50-2, and the tapered shape of the tapered portion with an inclination angle can be defined.

[0092] When the cross-section of the optical waveguides 21-1, 21-2 on the light input side and the optical waveguide 22 on the light output side that is perpendicular to the extension direction is rectangular or trapezoidal (the upper base is smaller than the lower base), for example, when the width of the upper surface of the optical waveguides 21-1, 21-2 on the light input side and the optical waveguide 22 on the light output side is set to 0.3 to 1.2 μm, the initial width of the tapered portions 51-1, 51-2, 52 is 0.3 to 1.2 μm, and the width of the portion connected to the MMI-type optical multiplexing device can be set to, for example, 0.5 to 2.5 μm, and the length of the tapered portion can be set to, for example, 10 to 500 μm.

[0093] The following effects are achieved by providing tapered portions at the input and output ports connected to the MMI-type optical multiplexing device. The optical waveguides on the optical input side and optical waveguides on the optical output side connected to the MMI-type optical multiplexing device are configured to propagate single-mode (0th-order mode, fundamental mode) laser light, while the MMI-type optical multiplexing device is configured to propagate multi-mode (0th-order mode to higher-order modes) laser light. Therefore, when inputting from the optical waveguide on the optical input side to the MMI-type optical multiplexing device and outputting from the MMI-type optical multiplexing device to the optical waveguide on the optical output side, coupling loss occurs due to the mode mismatch between the incident single mode and the multimode. In contrast, providing tapered portions at the input and output ports mitigates the mode mismatch between the single mode and the multimode, reducing coupling loss. The wider the width of the tapered portion, the greater the mode mismatch is mitigated, and the greater the reduction in coupling loss.

[0094] In the optical multiplexer disclosed in the present invention, the optical waveguide on the light input side and the optical waveguide on the light output side are not limited to have a tapered portion. Figure 2 As in the illustrated optical multiplexer 101 , the optical waveguide on the light input side and the optical waveguide on the light output side have a structure without a tapered portion.

[0095] Figure 3 It is used to make Figure 1 The optical multiplexer 100 shown is an optical multiplexer of an MMI type optical multiplexing section in which two laser beams are combined and transmitted through the optical waveguide 21 - 1 on the light input side.

[0096] Figure 3 The optical combiner 102 shown has Figure 1 In addition to the illustrated optical multiplexer 100, the optical multiplexer further includes a pre-MMI-type optical multiplexing section 150 disposed on the input side relative to the MMI-coupled optical multiplexing section 50, two pre-optical input-side optical waveguides 121-1 and 121-2 connected to the pre-MMI-type optical multiplexing section 150, and a pre-optical output-side optical waveguide 122T connected to the pre-MMI-type optical multiplexing section 150. The pre-optical output-side optical waveguide 122T is connected to the two-color propagation optical input-side optical waveguide 21-1. The pre-optical output-side optical waveguide 122T and the two-color propagation optical input-side optical waveguide 21-1 are integral and do not need to be separated.

[0097] exist Figure 3 In the optical multiplexer 102 shown, the pre-MMI type optical multiplexing section 150 is an MMI single type optical multiplexing section, but may also be an MMI coupling type optical multiplexing section.

[0098] The MMI coupling type optical multiplexing section 50 and the pre-MMI type optical multiplexing section 150 constitute two stages of MMI coupling type optical multiplexing sections connected via the pre-light output side optical waveguide 122T and the two-color propagation light input side optical waveguide 21 - 1 .

[0099] The optical multiplexer 102 is a 3×1 type (three input ports and one output port) optical multiplexer having three light incident ports (a first light incident port 121 - 1 i , a second light incident port 121 - 2 i , and a third light incident port 21 - 2 i ) and one light output port 22To.

[0100] exist Figure 3 In the optical combiner 102 shown, the two pre-light input-side optical waveguides 121-1 and 121-2 connected to the pre-MMI-type optical combining section 150 have tapered portions 151-1 and 151-2 whose width continuously widens as they approach the pre-MMI-type optical combining section 150, and whose tapered shape with an inclination angle can be defined. In addition, the one pre-light output-side optical waveguide 122T connected to the pre-MMI-type optical combining section 150 has a tapered portion 152 whose width continuously widens as it approaches the pre-MMI-type optical combining section 150, and whose tapered shape with an inclination angle can be defined. The two pre-light input-side optical waveguides 121-1 and 121-2 and the one pre-light output-side optical waveguide 122T are not limited to structures having tapered portions, and may also be structures in which the light input-side optical waveguide and the light output-side optical waveguide do not have tapered portions (see FIG. 2 ). Figure 2 ).

[0101] use Figure 4A 、 Figure 4B and Figure 5A 、 Figure 5B , the principle of the MMI type optical combiner is explained. Figure 4A Indicates the width W of the MMI optical combiner M We is the effective width of the MMI optical combiner, which is approximated by the width of the effective MMI optical combiner in the 0th-order mode (fundamental mode), taking into account the light mode bleeding or Goos-Haenchen shift. Figure 4B It is a diagram showing the simulation results of the electromagnetic field distribution in the waveguide cross section of each of the single mode (TMO), the higher-order mode (TM1), and the higher-order mode (TM2).

[0102] In an MMI-type optical combiner, multiple modes, from the 0th-order mode to higher-order modes, interfere with each other and form an image (focus) at a specific location in the MMI-type optical combiner (a predetermined distance from the input terminal). It is known that the distance between adjacent focused points, or the period (beat length), Lπ, roughly follows equation (1). Equation (1) represents the beat length, Lπ, between the lower-order modes of the 0th-order mode and the 1st-order mode.

[0103]

Mathematical formula 1

[0104]

[0105] In equation (1), We is the effective width of the MMI-type optical combiner, n is the effective refractive index of the MMI, and λ is the wavelength of the input light. β0 and β1 are the propagation constants of the 0th-order mode and the 1st-order mode, respectively. As can be seen from equation (1), the beat length depends on the width and wavelength of the MMI-type optical combiner.

[0106] When the electromagnetic field distribution experiences a 2π phase change across all propagation modes generated within the MMI optical combiner, the light intensity distribution becomes aligned with the incident light intensity distribution. The distance required for light to propagate until this alignment (focusing) is called the self-projection distance. Focusing is repeated at a period of Lπ after a certain propagation distance of 3Lπ / 4.

[0107] Figure 5A 、 Figure 5B The diagram shows the results of a simulation using simulation software (Fimmwave, a product of Photon Design) of the electromagnetic field distribution along the cross section of a 2×1 MMI optical combiner (R / G coupler) along the light propagation direction (x direction). In the simulated model, the y-direction position (coordinate) of the input waveguide of the optical combiner inputted with red (R) light of 638nm wavelength is the same as the y-direction position (coordinate) of the output waveguide of the optical combiner, and the y-direction position of the input waveguide of the optical combiner inputted with green (G) light of 520nm wavelength is separated by a predetermined distance. Brighter colors indicate locations where the modes interfere more strongly ("strong" in the diagram), darker colors indicate locations where the modes interfere less strongly ("weak" in the diagram), and intermediate colors indicate locations where the interference between the modes is intermediate ("medium" in the diagram).

[0108] Figure 5A The results of the simulation of the electromagnetic field distribution of red (R) light are shown. Figure 5B The results of simulations of the electromagnetic field distribution of green (G) light are shown.

[0109] exist Figure 5A and Figure 5BSince all of the wavelengths have a portion that strongly interferes near the output port of the optical combiner, it is preferable to set the length (length in the X direction) of the MMI-type optical combiner so that this position is as consistent as possible (i.e., as close as possible to an integer multiple (lowest common multiple) of the beat length of each input wavelength). However, due to the influence of phase differences caused by the input position of each input wavelength into the optical combiner, the length of the MMI-type optical combiner cannot be determined solely by integer multiples of the beat length of each input wavelength.

[0110] Therefore, the length of the optical multiplexer needs to be adjusted based on the integer multiples (lowest common multiple) of the beat lengths of the input wavelengths, taking into account the influence of the phase caused by the input position of each input wavelength into the optical multiplexer.

[0111] Figure 6A and Figure 6B This graph shows the relationship between the length and beat length of the first MMI-type optical combining device (first stage) and the second MMI-type optical combining device (second stage) and output intensity for red (R) and green (G) laser light, respectively. The horizontal axis represents the length (L1, L2) of the MMI-type optical combining section, and the vertical axis represents light intensity.

[0112] The beat lengths of red (R) and green (G) are different. If the lengths of the first and second MMI-type optical multiplexing devices are set to approximately 700 μm, both red (R) and green (G) can be multiplexed at an output intensity of 0.3.

[0113] 〔Photosynthesis Component〕

[0114] The optical multiplexing component disclosed herein comprises a substrate composed of a material different from lithium niobate, and a lithium niobate film formed on a principal surface of the substrate, with the optical multiplexing device of the aforementioned embodiment formed on the lithium niobate film. Components described below will be assigned the same reference numerals as those in the aforementioned embodiment, and their description may be omitted.

[0115] The lithium niobate film of the optical multiplexing component of the present disclosure may also have the following Figures 1 to 3 The optical combining section is shown.

[0116] Figure 7 Schematic top view of the optical combining component of the present invention.

[0117] exist Figure 7In the optical combining component 200 shown, three light incident ports (a first light incident port 121-1i, a second light incident port 121-2i, and a third light incident port 21-2i) are provided on the first side 200A, and one light output port 22To is provided on the third side 200C opposite to the first side 200A. However, the light output port 22To can also be provided on the second side 200B or the fourth side 200D adjacent to the first side 200A.

[0118] Figure 8 yes Figure 7 The optical combining component 200 shown is formed by the YZ plane ( Figure 7 Schematic diagram of the cross section of the X-X').

[0119] Figure 8 The optical multiplexing component 200 shown includes a substrate 10 made of a material different from lithium niobate and a lithium niobate film 24 formed on the main surface of the substrate 10. Figure 1 The optical combiner shown is formed on a lithium niobate film 24 .

[0120] like Figure 9 As shown, the lithium niobate film 24 may also be structured to consist of a ridge 24-1 protruding from the first surface 24A and a slab layer 24-2, which is the portion outside the ridge. The ridges form the light input-side optical waveguides 21-1, 21-2, and 21-3, the first MMI-type optical multiplexing device 50-1, the second MMI-type optical multiplexing device 50-2, and the light output-side optical waveguide 22T. The lithium niobate film 24 is coated with a buffer film 23. The lithium niobate film 24 and the buffer film 23 are collectively referred to as the optical multiplexing functional layer 20.

[0121] When the optical multiplexing component of this embodiment is used in a spectacles-type image display device, the thickness (T slab ) is preferably 0.1 to 0.3 μm.

[0122] When the optical multiplexing device of this embodiment is used in a spectacles-type image display device, the thickness of the ridge 24 - 1 (T R ) is preferably 0.5 to 1.0 μm. The reason is that if the thickness of the ridge 24-1 (T R ) is small, the light does not propagate; if it is large, the propagated light becomes multimode.

[0123] When the optical multiplexing component of this embodiment is used in a spectacles-type image display device, the width of the upper surface of the ridge (W R ) is preferably 0.3 to 1.2 μm. This is because if the waveguide width is small, light does not propagate, and if it is large, the propagated light becomes multimode.

[0124] When the optical multiplexing component of this embodiment is used in a spectacles-type image display device, the lower inner angle (α) of the ridge 24 - 1 having a trapezoidal cross section is set to be greater than 65°. This is because as the lower inner angle (inclination angle) decreases, the propagating light becomes multimode.

[0125] In the optical combining component 200, when the refractive index difference between the lithium niobate film and the buffer film is set to △n, if the lithium niobate film is set to lithium niobate, then compared with materials such as glass, △n can be designed to be a larger value, the curvature radius of the optical waveguide can be reduced, and by further using a multi-mode interference optical combining part, the increase in coupling length can be prevented compared with the case of using a directional coupler, thereby achieving both increased design freedom and miniaturization.

[0126] Examples of the substrate 10 include a sapphire substrate, a Si substrate, and a thermally oxidized silicon substrate.

[0127] The substrate 10 is not particularly limited as long as it is a material with a lower refractive index than the lithium niobate (LiNbO3) film. However, as a substrate capable of forming a single-crystal lithium niobate film into an epitaxial film, a sapphire single-crystal substrate or a silicon single-crystal substrate is preferably used. The crystal orientation of the single-crystal substrate is not particularly limited. However, for example, since a c-axis-oriented lithium niobate film has three-dimensional symmetry, it is desirable that the underlying single-crystal substrate also has the same symmetry. In the case of a sapphire single-crystal substrate, a c-plane substrate is preferred, while in the case of a silicon single-crystal substrate, a (111) plane substrate is preferred.

[0128] The lithium niobate film is, for example, a c-axis oriented lithium niobate film. The lithium niobate film is, for example, an epitaxial film grown epitaxially on substrate 10. An epitaxial film is a single crystal film whose crystal orientation is aligned by a base substrate. An epitaxial film has a single crystal orientation in the Z direction and in the xy plane, with the crystals aligned in the x-, y-, and z-axis directions. Whether a film formed on substrate 10 is an epitaxial film can be verified, for example, by confirming the peak intensity and pole at the orientation position in 2θ-θ X-ray diffraction.

[0129] Specifically, when performing measurements based on 2θ-θ X-ray diffraction, the intensities of all peaks other than the target plane are 10% or less, preferably 5% or less, of the maximum peak intensity of the target plane. For example, in the case of a c-axis oriented epitaxial lithium niobate film, the intensities of peaks other than the (00L) plane are 10% or less, preferably 5% or less, of the maximum peak intensity of the (00L) plane. (00L) is a general term for equivalent planes such as (001) and (002).

[0130] In addition, under the conditions for confirming the peak intensity at the above-mentioned orientation position, only the orientation in one direction is shown. Therefore, even if the above-mentioned conditions are obtained, when the in-plane crystal orientation is not aligned, the intensity of the X-rays at a specific angle position will not increase, and no poles can be seen. For example, in the case of a lithium niobate film, since LiNbO3 has a trigonal crystal structure, there are three poles of LiNbO3 (014) in the single crystal. In the case of lithium niobate, it is known that epitaxial growth occurs in a so-called twin state in which the crystals are symmetrically coupled by rotating 180° around the c-axis. In this case, since the three poles become symmetrically coupled to two, there are six poles. In addition, in the case of a lithium niobate film formed on a (100)-plane silicon single crystal substrate, since the substrate becomes four-fold symmetric, 4×3=12 poles are observed. In addition, in the present disclosure, a lithium niobate film epitaxially grown in a twin state is also included in the epitaxial film.

[0131] The composition of lithium niobate is Li x NbA y O z . A is an element other than Li, Nb, and O. x is greater than or equal to 0.5 and less than or equal to 1.2, preferably greater than or equal to 0.9 and less than or equal to 1.05. y is greater than or equal to 0.5 and less than or equal to 0.5. z is greater than or equal to 1.5 and less than or equal to 4.0, preferably greater than or equal to 2.5 and less than or equal to 3.5. Elements of A include K, Na, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Zn, Sc, and Ce, and may be a combination of two or more of these elements.

[0132] Furthermore, the lithium niobate film may be a lithium niobate single crystal thin film bonded to a substrate.

[0133] [Optical multiplexing components with optical modulation function]

[0134] The optical multiplexing component with optical modulation function of this embodiment includes a substrate made of a material different from lithium niobate, and a lithium niobate film formed on the main surface of the substrate. The optical multiplexing device and Mach-Zehnder optical modulator of the above-mentioned embodiment are integrated on the lithium niobate film. The Mach-Zehnder optical modulator is connected to the optical multiplexing device and guides multiple visible light beams emitted from multiple visible light laser light sources to the optical multiplexing device. Components described below that have the same functions as those in the above-mentioned embodiment are denoted by the same reference numerals, and their description may be omitted.

[0135] The lithium niobate film of the optical multiplexing component with light modulation function of this embodiment may also have Figures 1 to 3 Any of the optical combiners shown.

[0136] Figure 10It is a schematic plan view of the optical multiplexing component with light modulation function according to this embodiment.

[0137] Figure 10 The optical multiplexing component 300 with light modulation function shown in FIG. 1 includes a substrate 10 made of a material different from lithium niobate (see FIG. 1 ). Figure 8 ) and a lithium niobate film 24 formed on the main surface of the substrate 10, and an optical multiplexer having an optical multiplexing component 300 with a light modulation function is formed in the lithium niobate film 24.

[0138] The optical multiplexing component 300 with an optical modulation function includes the 3×1 type optical multiplexing device 102 of the above embodiment (see Figure 3 ) and a Mach-Zehnder type optical modulator 40.

[0139] The Mach-Zehnder optical modulator 40 can be a well-known Mach-Zehnder optical modulator or an optical waveguide. It splits (demultiplexes) a light beam with the same wavelength and phase into two pairs of beams, assigns different phases to each pair, and then combines (combines) the two beams. The intensity of the combined light beam changes depending on the phase difference.

[0140] Figure 10 The illustrated Mach-Zehnder optical waveguides 40 - 1 , 40 - 2 , and 40 - 3 each include a first optical waveguide 41 , a second optical waveguide 42 , an input path 43 , an output path 44 , a branching portion 45 , and a coupling portion 46 .

[0141] The output path 44 of the Mach-Zehnder optical waveguide 40-1 is connected to the optical waveguide 21-1 on the light input side of the first MMI-type optical multiplexing device 50-1. Furthermore, the output path 44 of the Mach-Zehnder optical waveguide 40-2 is connected to the optical waveguide 21-2 on the light input side of the first MMI-type optical multiplexing device 50-1. Furthermore, the output path 44 of the Mach-Zehnder optical waveguide 40-3 is connected to the optical waveguide 21-3 on the light input side of the first MMI-type optical multiplexing device 50-1.

[0142] Figure 10 The first optical waveguide 41 and the second optical waveguide 42 shown in the figure are configured to extend linearly in the x-direction except for the vicinity of the branching portion 45 and the vicinity of the coupling portion 46 , but the present invention is not limited to such a configuration. Figure 10 The first optical waveguide 41 and the second optical waveguide 42 are shown as having substantially the same length. A branch portion 45 is located between the input path 43 and the first and second optical waveguides 41, 42. The input path 43 is connected to the first and second optical waveguides 41, 42 via the branch portion 45. A coupling portion 46 is located between the first and second optical waveguides 41, 42 and the output path 44. The first and second optical waveguides 41, 42 are connected to the output path 44 via the coupling portion 46.

[0143] Electrodes 25 and 26 are electrodes that apply a modulation voltage to each Mach-Zehnder optical waveguide 40-1, 40-2, and 40-3 (hereinafter sometimes referred to as "each Mach-Zehnder optical waveguide 40"). Electrode 25 is an example of a first electrode, and electrode 26 is an example of a second electrode. One end of electrode 25 is connected to a power supply 131, and the other end is connected to a terminal resistor 132. Electrode 26 is connected to a power supply 131 at one end, and the other end is connected to a terminal resistor 132 at the other end. Power supply 131 is part of a drive circuit that applies a modulation voltage to each Mach-Zehnder optical waveguide 40. To simplify the figure, electrodes 25 and 26 are depicted only in the portion of Mach-Zehnder optical waveguide 40-3.

[0144] Electrodes 27 and 28 apply a DC bias to each Mach-Zehnder waveguide 40. One end of electrode 27 and one end of electrode 28 are connected to a power supply 133. Power supply 133 is part of a DC bias application circuit that applies a DC bias to each Mach-Zehnder waveguide 40.

[0145] When a DC bias is superimposed on the electrodes 25 and 26, the electrodes 27 and 28 may not be provided. Alternatively, a ground electrode may be provided around the electrodes 25, 26, 27, and 28.

[0146] [Visible Light Source Module (First Embodiment)]

[0147] A visible light source module according to a first embodiment of the present disclosure includes the optical multiplexer according to the present disclosure and a plurality of visible light laser light sources that emit visible light multiplexed by the optical multiplexer.

[0148] Figure 11 2 is a schematic top view of the visible light source module disclosed in the present invention.

[0149] Figure 11 The visible light source module 1000 shown includes an optical combining component 200 and three visible light laser light sources 30 (30-1, 30-2, 30-3). The optical combining component 200 includes an MMI-coupled optical combining section 50 connected to a first MMI-type optical combining device 50-1 and a second MMI-type optical combining device 50-2. The three visible light laser light sources 30 emit visible light combined by the optical combining component 200. The optical combining component 200 includes a substrate 10 made of a material different from lithium niobate (see Figure 8 ), and the lithium niobate film 24 formed on the main surface of the substrate 10 (see Figure 8 ), having side 200A.

[0150] for Figure 11 The components shown in the figure have the same functions as those described above, and the same reference numerals are given, and their description may be omitted.

[0151] Various laser elements can be used as the visible light laser light source 30. For example, commercially available red, green, or blue laser diodes (LDs) can be used. Red light can use light with a peak wavelength of 610 nm to 750 nm, green light can use light with a peak wavelength of 500 nm to 560 nm, and blue light can use light with a peak wavelength of 435 nm to 480 nm.

[0152] In the visible light source module 1000, the visible light laser light sources 30-1, 30-2, and 30-3 are respectively configured as LDs emitting green light, blue light, and red light. The visible light laser light sources 30-1, 30-2, and 30-3 are spaced apart from each other in a direction substantially perpendicular to the emission direction of light emitted from each LD, and are mounted on a light source base 60 (see FIG. Figure 12 )'s upper surface.

[0153] In the visible light source module 1000, the number of visible light laser light sources is shown as two or three, but as long as there are multiple, it is not limited to two or three, and can be four or more. The multiple visible light laser light sources can be light sources that emit light of different wavelengths. In addition, there can also be visible light laser light sources that emit light of the same wavelength. In addition, the emitted light can also use light other than red (R), green (G), and blue (B). The order of mounting red (R), green (G), and blue (B) described using the drawings does not necessarily need to be in this order and can be appropriately changed.

[0154] Figure 12 Cut by XZ plane Figure 11 FIG1 is a schematic cross-sectional view of a portion of the light source module 1000. Only a portion near the joint is depicted.

[0155] The light source 7 is provided on the upper surface of the light source base 60. The light source base 60 may be common to all the light sources or may be separate for each light source.

[0156] The light source base 60 is made of, for example, aluminum nitride (AlN), aluminum oxide (Al 2 O 3 ), silicon (Si), or the like.

[0157] The light source base 60 and the optical waveguide substrate 10 having the optical multiplexing functional layer 20 formed thereon can be directly bonded via the metal layer 70. This structure eliminates the need for spatial coupling or fiber coupling, thereby enabling further miniaturization.

[0158] By setting a structure in which the bonding surface 60A of the light source base 60 and the bonding surface 10A of the substrate 10 for the optical waveguide are bonded via the metal layer 70, the relative positions of the light source base 60 and the substrate 10 for the optical waveguide can be adjusted during manufacturing, and the optical axis position of the laser can be aligned (active alignment) in such a way that the optical axis of each light source 30 is consistent with the axis of the input waveguide.

[0159] The metal layer 70 can be composed of a plurality of metal layers.

[0160] When the light source module of this embodiment is used in XR glasses, based on the amount of light required in the XR glasses, the gap (interval) S between the bonding surface 60A of the light source base 60 and the bonding surface 10A of the substrate 10 for the optical waveguide is preferably greater than 0 μm and less than 5 μm, for example.

[0161] (Drive method)

[0162] An optical modulator modulates input light into output light using a high-frequency modulation voltage and a DC bias. By controlling the DC bias voltage Vdc, the optical modulator's operating point Vd is adjusted. Operating point Vd is the voltage at the center of the modulation voltage amplitude Vpp. The half-wave voltage of the high-frequency modulation voltage is Vπ(RF).

[0163] Figures 13A to 13C These are diagrams for explaining three examples of the method of driving the optical modulator.

[0164] exist Figures 13A to 13C In the figure, the horizontal axis represents the DC bias voltage applied to the optical modulator, and the vertical axis represents the intensity of the light output under the applied voltage. The applied voltage width Vpp is the difference between the minimum value (Vmin) and the maximum value (Vmax) of the applied voltage.

[0165] exist Figure 13A In the example, if the operating point Vd' is set so that the offset of the operating point voltage becomes (Vn-0.5Vπ), the DC bias voltage can be approximately 0V. For example, if the applied voltage width Vpp of the modulation voltage Vm is set to the half-wave voltage Vπ(RF), a modulation voltage Vm in the range of (-1 / 2)Vπ(RF) to (1 / 2)Vπ(RF) is applied to the optical modulator. Figure 13A As shown, the light output from the optical modulator is maximum when the modulation voltage Vm is (-1 / 2)Vπ(RF), minimum when the modulation voltage Vm is (1 / 2)Vπ(RF), and the light output when the modulation voltage Vm is 0V is 50% of the maximum output.

[0166] Likewise, using Figure 13BThe optical modulation of an optical modulator is described in which the operating point Vd' is set so that the offset of the operating point voltage becomes (Vn-0.25Vπ) and the applied voltage width Vpp of the modulation voltage Vm is controlled to (1 / 4) wavelength voltage (1 / 2)Vπ(RF).

[0167] In this case, if the offset of the operating point voltage is set to (Vn-0.25Vπ), the operating point Vd' can be set to a DC bias voltage of approximately 0 (V). A modulation voltage Vm corresponding to the range of (-1 / 4)Vπ(RF) to (1 / 4)Vπ(RF) is applied to the optical modulator. Figure 13B As shown, the light output from the optical modulator is maximum when the modulation voltage Vm is (-1 / 4)Vπ(RF), minimum when the modulation voltage Vm is (1 / 4)Vπ(RF), and the light output when the modulation voltage Vm is 0V (Vd') is 15% of the maximum output.

[0168] Likewise, using Figure 13C The optical modulation of an optical modulator is described in which the operating point Vd' is set so that the offset of the operating point voltage becomes (Vn-0.75Vπ) and the applied voltage width Vpp of the modulation voltage Vm is controlled to (1 / 4) wavelength voltage (1 / 2)Vπ(RF).

[0169] In this case, if the offset of the operating point voltage is set to (Vn-0.75Vπ), the operating point Vd' can be set to a DC bias voltage of approximately 0 (V). A modulation voltage Vm corresponding to the range of (-1 / 4)Vπ(RF) to (1 / 4)Vπ(RF) is applied to the optical modulator. Figure 13C As shown, the light output from the optical modulator is maximum when the modulation voltage Vm is (-1 / 4)Vπ(RF), minimum when the modulation voltage Vm is (1 / 4)Vπ(RF), and 85% of the maximum output when the modulation voltage Vm is 0V(Vd').

[0170] [Visible Light Source Module (Second Embodiment)]

[0171] Figure 14 FIG. 1 is a schematic top view of a visible light source module according to a second embodiment of the present disclosure.

[0172] Figure 14 The visible light source module 2000 shown in FIG1 includes an optical multiplexing component 300 with a light modulation function and a plurality of visible light laser light sources 30 (30-1, 30-2, 30-3) that emit visible light multiplexed by the optical multiplexing component 300 with a light modulation function. The optical multiplexing component 300 with a light modulation function includes a substrate 10 made of a material different from lithium niobate (see FIG10 ). Figure 8), and the lithium niobate film 24 formed on the main surface of the substrate 10 (see Figure 8 ), having side 300A.

[0173] for Figure 14 The components shown in the figure are denoted by the same reference numerals as those described above, and their description may be omitted.

[0174] Visible light source module 2000 includes three Mach-Zehnder optical waveguides 40-1, 40-2, and 40-3, the same number as the visible light laser light sources 30-1, 30-2, and 30-3. The visible light laser light sources 30-1, 30-2, and 30-3 and the Mach-Zehnder optical waveguides 40-1, 40-2, and 40-3 are positioned so that light emitted from the visible light laser sources is incident on the corresponding Mach-Zehnder optical waveguides.

[0175] A structure can be employed in which the light source base 60 on which the visible light laser light sources 30-1, 30-2, and 30-3 are mounted and the substrate 10 on which the optical multiplexing functional layer 20 of the optical multiplexing component 300 having a light modulation function is formed are directly bonded via a metal bonding layer. This structure eliminates the need for spatial coupling or fiber coupling, allowing for further miniaturization.

[0176] Furthermore, the relative positions of the light source base 60 and the substrate 10 can be adjusted during manufacturing to align the optical axis of each visible light laser with the axis of the input path 43 of each Mach-Zehnder waveguide 40-1, 40-2, 40-3 (active alignment).

[0177] The size of the optical combining functional layer 20 is, for example, 100 mm. 2 If the size of the optical wave combining function layer 20 is 100 mm 2 The following are suitable for use as XR glasses such as AR glasses or VR glasses.

[0178] The light-combining functional layer 20 can be produced by a known method, such as epitaxial growth, photolithography, etching, vapor phase growth, and metallization, and other semiconductor processes.

[0179] When the visible light source module of the present invention is used as XR glasses such as AR glasses or VR glasses, the width of the first MMI-type optical combiner device and the second MMI-type optical combiner device constituting the optical combiner is preferably set to about 5 to 15 μm, and the length thereof is preferably set to about 100 to 1000 μm, for example.

[0180] For example, in a retinal projection display, in order to display an image in the desired color, the intensity of each of the three colors (RGB) representing visible light must be independently and rapidly modulated. If only a visible light laser light source (current modulation) performs this modulation, the load on the IC controlling this modulation will increase. However, it is also possible to use modulation (voltage modulation) performed by a Mach-Zehnder optical modulator 40 (optical multiplexing component 300 with light modulation function) in combination. In this case, coarse adjustment can be performed using current (visible light laser light source) and fine adjustment can be performed using voltage (Mach-Zehnder optical modulator 40). Alternatively, coarse adjustment can be performed using voltage (Mach-Zehnder optical modulator 40) and fine adjustment can be performed using current (visible light laser light source). Preferably, the voltage-based fine adjustment method is used when responsiveness is important, as it has good responsiveness. The current-based fine adjustment method is used when power consumption is important, as it can use low current.

[0181] [Optical engine and XR glasses]

[0182] In this specification, an optical engine refers to a device comprising: a plurality of light sources; an optical system comprising a combining section for combining a plurality of light beams emitted from the plurality of light sources into a single light beam; a light scanning mirror for changing the angle of light emitted from the optical system and reflecting the light in such a manner as to display an image; and a control element for controlling the light scanning mirror.

[0183] Figure 15 This is a conceptual diagram for explaining an example of the XR glasses of the present invention. Figure 16 It means in Figure 15 This is a conceptual diagram of XR glasses projecting an image directly onto the retina using laser light emitted from a light source module. Symbol L represents image display light.

[0184] The XR glasses 10000 of this embodiment are glasses-type terminals. XR is a general term for virtual reality (VR), augmented reality (AR), and mixed reality. Figure 16 The symbol L shown is image display light.

[0185] At once Figure 15 In the XR glasses 10000 of the present embodiment shown, the light source module 1000 of the above-described embodiment is mounted on an optical engine 5001 provided on a frame 1010 .

[0186] like Figure 15As shown, the optical engine 5001 includes a light source module 1000, a light scanning mirror 3001, an optical system 2001 connecting the light source module 1000 and the light scanning mirror 3001, a laser driver 1100, a light scanning mirror driver 1200, and a video controller 1300 for controlling these drivers.

[0187] For example, a MEMS mirror can be used as the light scanning mirror 3001. To project a 2D image, a biaxial MEMS mirror is preferably used as the light scanning mirror 3001, which vibrates to reflect laser light while changing angles in the horizontal direction (X direction) and the vertical direction (Y direction).

[0188] The optical system 2001 optically processes the laser light emitted from the light source module 1000. As the optical system 2001, for example, an optical system including a collimating lens 2001a, a slit 2001b, and an ND filter 2001c can be used. Figure 15 The optical system 2001 shown is an example and other structures are also possible.

[0189] exist Figure 15 In the XR glasses 10000 of this embodiment shown in FIG. Figure 16 As shown, the laser R irradiated from the light source module 1000 installed on the frame 1010 is reflected by the light scanning mirror 3001, and further reflected by the lens 4001 of the XR glasses 10000, and enters the human eyeball E as image display light L, and can directly project an image (image) on the retina M.

[0190] Since the XR glasses 10000 of this embodiment are equipped with the light source module 1000 of this embodiment, the electric field efficiency is reduced.

[0191] The embodiments of the present invention are described above in detail with reference to the accompanying drawings, but the various structures and their combinations in the various embodiments are merely examples, and additions, omissions, replacements, and other changes to the structures may be made without departing from the spirit of the present invention.

[0192] [Example]

[0193] Hereinafter, the present invention will be described in further detail using examples. However, the present invention is not limited to any of the following examples.

[0194] Three-input, one-output MMI-connected optical multiplexing unit

[0195] for Figure 3The simulations compared the coupling loss (the loss in light intensity at output after the input light intensity passes through the MMI-linked optical multiplexing unit) of the three-input, one-output MMI-linked optical multiplexing unit model shown above with a model that differs only in that it lacks the second MMI-linked optical multiplexing device. The simulation software used was Fimmwave (Photon Design).

[0196] [Example 1]

[0197] The dimensions of the MMI-coupled optical multiplexing section 50 formed by coupling the first MMI-type optical multiplexing device 50-1 and the second MMI-type optical multiplexing device 50-2, and the pre-MMI-type optical multiplexing section 150 arranged on the input side of the MMI-coupled optical multiplexing section 50 are as follows: (See Figure 17 )

[0198] (Length and width of each component)

[0199] Length L1 of the first MMI-type optical multiplexing device: 680 μm

[0200] Width W1 of the first MMI-type optical multiplexing device: 5.6 μm

[0201] Length L2 of the second MMI-type optical multiplexing device: 90 μm

[0202] Width W2 of the second MMI-type optical multiplexing device: 2.8 μm

[0203] Length L3 of the pre-MMI optical multiplexing unit: 525 μm

[0204] Width W3 of the pre-MMI optical multiplexing unit: 6 μm

[0205] Width Wl of the optical waveguide on the light input side in 、W3 in :2μm

[0206] Width W2 of the optical waveguide on the light output side out 、W3 out :2μm

[0207] Width of optical waveguide excluding the tapered portion: 0.8 μm (common)

[0208] In addition, the width W1 of the optical waveguide (ridge) on the light input side is in 、W3 in and the width W2 of the optical waveguide (ridge) on the light output side outThe width of the portion connected to the MMI-type optical combiner is used. A tapered shape with a continuously increasing width from a predetermined position of the optical waveguide to the portion connected to the MMI-type optical combiner, and a defined inclination angle, is used as the top view from the Z direction. The tapered portion has a length of 50 μm and gradually widens from a width of 0.8 μm to a width of 2 μm at the portion connected to the MMI-type optical combiner (W in 、W out ). (Wavelength of the optical waveguide on the light input side)

[0209] Wavelength of the light input side optical waveguide 21-1: 637 μm (red R)

[0210] Wavelength of the optical waveguide 21-2 on the light input side: 455 μm (blue B)

[0211] Wavelength of the optical waveguide 21-3 on the light input side: 520 μm (green G)

[0212] (Distance between adjacent optical waveguides on the light input side)

[0213] Distance d1 between the upper surfaces of adjacent light input side optical waveguides: 1.5 μm

[0214] Furthermore, as shown in the figure, the distance d1 between the upper surfaces is the distance between the upper surfaces of the portions connected to the MMI-type optical multiplexing sections of the adjacent light input-side optical waveguides.

[0215] [Comparative Example 1]

[0216] The model of the MMI-connected optical multiplexing section of Comparative Example 1 is the same model as that of Example 1, and the same parameters are used, except that the MMI-connected optical multiplexing section corresponding to the MMI-coupled optical multiplexing section 50 of Example 1 is an MMI-single optical multiplexing section without a second MMI-type optical multiplexing element.

[0217] Figure 18A and Figure 18B The graphs are for Example 1 and Comparative Example 1, respectively. The horizontal axis represents the length L1 of the first MMI-type optical multiplexing device, and the vertical axis represents the light intensity loss after each RGB wavelength passes through the MMI-connected optical multiplexing section.

[0218] The hollow arrows indicate the minimum value of the light intensity loss at each wavelength, and the range indicated by M indicates the magnitude of the variation in the margin of the RGB combining loss.

[0219] Compare Figure 18A and Figure 18B It is found that the variation in the margin of the RGB multiplexing loss is significantly improved in Example 1 including the second MMI-type optical multiplexing device, compared to Comparative Example 1 not including the second MMI-type optical multiplexing device.

[0220] exist Figure 18A In Example 1, the minimum value of the loss of light intensity of each color of RGB is within the range of 688.5±6.5μm. In contrast, Figure 18B In Comparative Example 1, the minimum value of the loss of light intensity of each color is 674.5±13.5 μm. Therefore, L1 that reduces the loss of light intensity of the three colors of RGB can be appropriately selected.

[0221] Furthermore, focusing on the minimum value of the loss of blue light intensity, Example 1 shifts from L1 = 661 μm in Comparative Example 1 to L1 = 685 μm, which is near the minimum values ​​for red and green light. Therefore, by adjusting the blue light intensity characteristics, which previously increased the margin variation in the combined loss, the margin variation in the combined loss of RGB can be improved.

Claims

1. An optical combiner, wherein: It is an optical combiner that combines multiple laser beams of different wavelengths. have: An MMI-coupled optical multiplexing section formed by coupling a first MMI-type optical multiplexing section and a second MMI-type optical multiplexing section having a width narrower than that of the first MMI-type optical multiplexing section from the input side; two optical waveguides on the light input side, connected to the first MMI-type optical multiplexing section; and a light output side optical waveguide connected to the second MMI-type optical multiplexing section, Of the two light input side optical waveguides, one light input side optical waveguide is a two-color propagation light input side optical waveguide for propagating a combined laser beam consisting of two laser beams of different wavelengths, and the other light input side optical waveguide is a single-color propagation light input side optical waveguide for propagating a single laser beam of a wavelength different from the two laser beams. The second MMI-type optical multiplexing section is arranged on an extension line of the monochromatic propagation light input-side optical waveguide.

2. The optical combiner according to claim 1, wherein: The width of the second MMI-type optical combining section is not less than 1 / 3 and not more than 2 / 3 of the width of the first MMI-type optical combining section.

3. The optical combiner according to claim 1, wherein: The second MMI-type optical multiplexing section has a length of 10 μm or more.

4. The optical combiner according to claim 1, wherein: The two light input side optical waveguides and the one light output side optical waveguide each have a tapered portion whose width gradually widens as it approaches the MMI coupling type optical multiplexing portion.

5. The optical combiner according to claim 1, wherein: have: a pre-MMI optical multiplexing section, which is arranged at a position closer to the input side than the MMI coupling type optical multiplexing section; two pre-input-side optical waveguides connected to the pre-MMI-type optical multiplexing section; and a pre-output-side optical waveguide connected to the pre-MMI-type optical multiplexing section, The pre-output-side optical waveguide is connected to the two-color propagation light input-side optical waveguide.

6. The optical combiner according to claim 1, wherein: The plurality of different wavelengths are all visible light wavelengths.

7. An optical wave combining component, wherein: have: a substrate composed of a material different from lithium niobate; and a lithium niobate film formed on the main surface of the substrate, The optical multiplexer according to any one of claims 1 to 6 is formed on the lithium niobate film.

8. A visible light source module, wherein: A device comprising the optical combining component according to claim 7 and a plurality of visible light laser light sources for emitting visible light combined by the optical combining component.

9. An optical multiplexing component with optical modulation function, wherein: The optical multiplexing device comprises: the optical multiplexing device according to claim 7; and a Mach-Zehnder optical modulator connected to the optical multiplexing device to guide a plurality of visible light beams emitted from a plurality of visible light laser light sources to the optical multiplexing device.

10. A visible light source module, wherein: A method of providing a method of providing a plurality of visible light laser light sources, comprising: providing an optical multiplexing component with an optical modulation function as described in claim 9; and emitting visible light multiplexed by the optical multiplexing component with an optical modulation function, wherein the plurality of visible light laser light sources are visible light laser light sources of red light, green light, and blue light.

11. An optical engine, wherein: have: The visible light source module according to claim 8; and A light scanning mirror changes the angle of the light emitted from the visible light source module and reflects the light in such a manner as to display an image.

12. An optical engine, wherein: have: The visible light source module according to claim 10; and A light scanning mirror changes the angle of the light emitted from the visible light source module and reflects the light in such a manner as to display an image.

13. An XR glasses, wherein: The optical engine according to claim 11 is mounted thereon.

14. An XR glasses, wherein: The optical engine according to claim 12 is mounted thereon.

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