Optical devices, light source modules and methods for manufacturing the same, optical engines, and XR glasses

Abstract

Ensure a stable supply of sufficient monitor light. [Solution] The optical device 10A according to the present invention comprises an optical functional layer on a substrate. The optical functional layer includes optical branching sections 120a, 120b, 120c that branch the visible light emitted from each visible light laser light source 301a, 301b, 301c, monitoring optical waveguides 130a, 130b, 130c connected to one output of each optical branching section 120a, 120b, 120c, and modulation optical waveguides 140a, 140b, 140c connected to the other output of each optical branching section 120a, 120b, 120c. The monitoring light propagating through the monitoring optical waveguides 130a, 130b, 130c is emitted from monitoring ports 131a, 131b, 131c. The indicator light propagating through the modulation optical waveguides 140a, 140b, and 140c is modulated by the optical modulation units 170a, 170b, and 170c, then combined by the optical multiplexer 180 and emitted from the optical output port 191.

Description

Technical Field

[0001] The present invention relates to an optical device, a light source module and a manufacturing method thereof, an optical engine, and XR glasses.

Background Art

[0002] In recent years, XR glasses such as AR (Augmented Reality) glasses and VR (Virtual Reality) glasses have attracted attention as small wearable devices. In XR glasses, it is important to miniaturize each component so as to fit into a normal glasses size. In particular, a retinal scanning display that allows a user to view an image by forming an image of two-dimensionally scanned light on the user's retina is expected. In this retinal scanning display, generally, light sources such as LEDs (Light Emitting Diodes) and LDs (Laser Diodes) corresponding to each of the colors R (red), G (green), and B (blue) are used. Visible light of each color emitted from each light source is combined and transmitted to an image display unit. The image display unit two-dimensionally scans the transmitted light and makes it enter the user's pupil. This incident light forms an image on the user's retina, and the user views the image.

[0003] Color representation in XR glasses and the like is realized by using visible light of each of the RGB colors. When adjusting the color balance of each of the RGB colors, the incident light corresponding to each color is branched, and the branched light is monitored as monitor light. By checking the light intensity of the monitor light, the color balance of each color can be adjusted.

[0004] Patent Document 1 discloses an optical multiplexer that is connectable to or integrateable with an optical modulator using a lithium niobate film and capable of adjusting the RGB color balance. The optical multiplexer disclosed in Patent Document 1 comprises a plurality of multimode interference optical multiplexers (first to third optical multiplexers), and visible light modulated by a Mach-Zehnder type optical modulator is input to each optical multiplexer. The first optical multiplexer is connected to a first optical input side optical waveguide, a first monitor light output side optical waveguide, and a first connecting optical waveguide. The second optical multiplexer is connected to a second optical input side optical waveguide, a first connecting optical waveguide, a second monitor light output side optical waveguide, and a second connecting optical waveguide. The third optical multiplexer is connected to a third optical input side optical waveguide, a second connecting optical waveguide, a third monitor light output side optical waveguide, and an optical output port connecting optical waveguide. The first to third monitor optical output side optical waveguides are all arranged so as not to intersect with other optical waveguides, thus preventing optical output loss (crossover loss). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-94959 [Overview of the project] [Problems that the invention aims to solve]

[0006] The optical multiplexer disclosed in Patent Document 1 has a configuration in which an optical multiplexer is connected downstream of a Mach-Zehnder type optical modulator. The visible light modulated by the optical modulator is separated by the optical multiplexer and output from the monitor light output port through the monitor light output side optical waveguide.

[0007] However, in order to obtain sufficient monitor light from the monitor light output port, the intensity of the visible light modulated by the optical modulator needs to be increased. If the light intensity is insufficient, sufficient light cannot be obtained from the monitor light output port, which presents a challenge as it affects measurement accuracy.

[0008] When using a Mach-Zehnder type optical modulator, the initial phase difference between the two optical waveguides can reduce the optical intensity. This phase difference depends on the initial setting without applied voltage, and an appropriate voltage must be applied to ensure sufficient optical intensity. In particular, when performing active alignment using a visible light laser source input to the optical input port and light from the monitor optical output port, an appropriate voltage must be applied to each optical modulator through which each visible light source propagates. This complicates the active alignment process and reduces work efficiency.

[0009] The present invention has been made in view of the above problems, and aims to provide an optical device, a light source module, a method for manufacturing the same, an optical engine, and XR glasses that can stably obtain sufficient monitor light from a monitor port. [Means for solving the problem]

[0010] To solve the above problems, the optical device according to the present invention is an optical device comprising a substrate and an optical functional layer formed on the main surface of the substrate, wherein the optical functional layer comprises, corresponding to each of a plurality of visible light laser light sources, an optical input port into which visible light emitted from each visible light laser light source can be incident, an input optical waveguide connected to each optical input port, an optical branching section having an input section and two output sections connected to each optical input port, a monitor optical waveguide connected to one output section of each optical branching section, a monitor port connected to each monitor optical waveguide for emitting monitor light to the outside, a first optical waveguide connected to the other output section of each optical branching section, an optical modulation section connected to each first optical waveguide, a second optical waveguide connected to each optical modulation section, an optical multiplexing section connected to each second optical waveguide, an output optical waveguide connected to the optical multiplexing section, and an optical output port connected to the output optical waveguide for emitting light combined in the optical multiplexing section to the outside.

[0011] To solve the above problems, the light source module according to the present invention is characterized by comprising the above-mentioned optical device and the plurality of visible light laser light sources.

[0012] To solve the above problems, the present invention provides a method for manufacturing a light source module, characterized in that visible light emitted from the visible light laser light source is incident on the optical input port, light emitted from the monitor port is incident on an optical detection device, the relative position of the visible light laser light source with respect to the optical device is adjusted based on the detection result of the optical detection device, and the visible light laser light source is fixed with respect to the optical device at a position where the optical axis of the visible light emitted from the visible light laser light source coincides with the center position of the optical input port.

[0013] To solve the above problems, the optical engine according to the present invention is characterized by comprising the above-mentioned light source module and an optical scanning mirror that reflects the light emitted from the light source module at a different angle to display an image.

[0014] To solve the above problems, the XR glasses according to the present invention are characterized by being equipped with the above-described optical engine. [Effects of the Invention]

[0015] The present invention can provide an optical device, a light source module, a method for manufacturing the same, an optical engine, and XR glasses that can stably obtain sufficient monitor light from a monitor port. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic plan view of a light source module according to the first embodiment of the present invention. [Figure 2] This is a schematic plan view showing the light source module in Figure 1 with the electrodes and pads removed. [Figure 3] This is a cross-sectional view along line AA in Figure 1. [Figure 4] This is a cross-sectional view along line BB in Figure 1. [Figure 5] This is a cross-sectional view along the CC line in Figure 1. [Figure 6] It is a schematic plan view of the tapered portion in FIGS. 1 and 2. [Figure 7] It is a schematic plan view of the intersecting waveguide in FIGS. 1 and 2. [Figure 8] It is a schematic plan view of the connected intersecting waveguide in FIGS. 1 and 2. [Figure 9] It is a schematic plan view of the high-order mode filter in FIGS. 1 and 2. [Figure 10] It is a diagram for explaining the active alignment executed in the manufacturing process of the light source module in the first embodiment of the present invention. [Figure 11] It is a diagram for explaining the concept of the active alignment executed in the first embodiment of the present invention. [Figure 12] It is a diagram for explaining the state in which an antireflection device is arranged near the monitor port of the light source module in the first embodiment of the present invention. [Figure 13] It is a conceptual diagram of the optical engine and XR glass in the first embodiment of the present invention. [Figure 14] It is a schematic plan view of the light source module in a derivative example of the first embodiment of the present invention. [Figure 15] It is a schematic plan view showing the state in which the electrodes and pad portions are removed from the light source module of FIG. 14. [Figure 16] It is a schematic plan view of the light source module in the second embodiment of the present invention. [Figure 17] It is a schematic plan view showing the state in which the electrodes and pad portions are removed from the light source module of FIG. 16. [Figure 18] It is a schematic plan view of the light source module in a derivative example of the second embodiment of the present invention. [Figure 19] It is a schematic plan view showing the state in which the electrodes and pad portions are removed from the light source module of FIG. 18. [Figure 20] It is a schematic plan view of the light source module in the third embodiment of the present invention. [Figure 21]Figure 20 is a schematic plan view showing the light source module with the electrodes and pads removed. [Figure 22] This is a schematic plan view of a light source module according to a fourth embodiment of the present invention. [Figure 23] Figure 22 is a schematic plan view showing the light source module with the electrodes and pads removed. [Modes for carrying out the invention]

[0017] Embodiments of the present invention will be described in detail below, with appropriate reference to the drawings. The drawings used in the following description may be enlarged for convenience to clearly illustrate the features, and the dimensions and proportions of each component may differ from those of the actual components. The materials, dimensions, etc., exemplified in the following description are merely examples. The present invention is not limited to these examples, and can be implemented with appropriate modifications within the scope of achieving the effects of the present invention. Furthermore, the "~" symbol indicating a numerical range means any numerical value within the range that includes the values ​​written before and after it as the lower and upper limits.

[0018] [First Embodiment] The first embodiment of the present invention will be described below.

[0019] <Light source module> The configuration of the light source module 1A in the first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic plan view of the light source module 1A in the first embodiment. Figure 2 is a schematic plan view showing the state in which the electrode 200 and pad portion 201 have been removed from the light source module 1A of Figure 1.

[0020] As shown in Figures 1 and 2, the light source module 1A includes a plurality of visible light laser light sources 301a, 301b, and 301c, and an optical device 10A.

[0021] In this specification, in the XYZ Cartesian coordinate system set out in the figure, the direction along one side of the optical device 10A is defined as the X direction, the direction perpendicular to the X direction is defined as the Y direction, and the direction perpendicular to both the X and Y directions is defined as the Z direction. The X direction coincides with the direction of light incidence from the multiple visible light laser sources 301a, 301b, and 301c to the optical device 10A. The Y direction is the width direction of the optical device 10A. The Z direction is perpendicular to the main surface of the optical device 10A. Hereafter, considering the orientation, we will express it as "positive Z direction," "negative Z direction," etc., and in particular, "positive Z direction" may be referred to as the upward direction, and "negative Z direction" as the downward direction. Note that the Z direction, which is the vertical direction, does not necessarily coincide with the direction in which gravity acts.

[0022] <Visible light laser light source> Multiple visible light laser light sources 301a, 301b, and 301c are configured to emit visible light (laser light) in different wavelength ranges, for example. Visible light laser light source 301a is a light source that emits laser light of a specific color and is not particularly limited, but for example, a laser diode (LD) or a laser light-emitting diode can be used.

[0023] The visible light laser light sources 301a, 301b, and 301c each emit visible light of the three primary colors (red, green, and blue). By superimposing these emitted lights based on the principle of additive color mixing, a desired color can be expressed. The visible light laser light sources 301a, 301b, and 301c may also emit light of colors other than the three primary colors.

[0024] In light source module 1A, visible light laser light source 301a emits red light, visible light laser light source 301b emits green light, and visible light laser light source 301c emits blue light. Visible light laser light source 301a is, for example, a red laser light source that emits laser light (red light) in the wavelength range of 590 nm to 800 nm. Visible light laser light source 301b is, for example, a green laser light source that emits laser light (green light) in the wavelength range of 490 nm to less than 590 nm. Visible light laser light source 301c is, for example, a blue laser light source that emits laser light (blue light) in the wavelength range of 380 nm to less than 490 nm. The arrangement order and number of visible light laser light sources 301a, 301b, and 301c that emit light in each wavelength range are not particularly limited.

[0025] Multiple visible light laser light sources 301a, 301b, and 301c are fixed to the optical device 10A. The visible light laser light sources 301a, 301b, and 301c may be mounted on the upper surface of the subcarriers 302a, 302b, and 302c, for example, in a bare chip state. In this case, the subcarriers 302a, 302b, and 302c are joined to the substrate 101 of the optical device 10A (see Figures 3 to 5) via bonding portions 303a, 303b, and 303c, such as metal bonding layers.

[0026] In order to properly direct the laser light emitted from the visible light laser sources 301a, 301b, and 301c into the optical input ports 110a, 110b, and 110c of the optical device 10A, optical axis adjustment is necessary. In the light source module 1A shown in Figure 1, as will be described later, the optical axes of the visible light laser sources 301a, 301b, and 301c can be adjusted based on the monitor light emitted from the monitor ports 131a, 131b, and 131c.

[0027] <Optical devices> The optical device 10A has a flat plate structure on which optical waveguides are formed two-dimensionally on the substrate 101. As shown in Figures 1 and 2, the optical device 10A has four end faces located on its side, namely the first end face 11, the second end face 12, the third end face 13, and the fourth end face 14.

[0028] The first end face 11 is the light incident surface on which the optical input ports 110a, 110b, and 110c are located. The second end face 12 is a surface substantially parallel to the first end face 11 and is located on the opposite side of the first end face 11. In the optical device 10A shown in Figures 1 and 2, the monitor ports 131a, 131b, and 131c are located on the second end face 12. The third end face 13 is a surface substantially perpendicular to the first end face 11 and the second end face 12 and is located on the left side (positive Y direction side) when viewed from the first end face 11. The fourth end face 14 is a surface substantially perpendicular to the first end face 11 and the second end face 12 and is located on the right side (negative Y direction side) when viewed from the first end face 11. In the optical device 10A shown in Figures 1 and 2, the optical output port 191 is located on the fourth end face 14.

[0029] Optical device 10A has an optical waveguide formed therein for propagating light. The optical waveguide of optical device 10A is designed to propagate the laser light emitted by the visible light laser sources 301a, 301b, and 301c, and to output it from the monitor ports 131a, 131b, 131c and the optical output port 191.

[0030] As shown in Figure 1, an electrode 200 is arranged on the upper (main) side of the optical device 10A. The electrode 200 is used to apply a driving voltage for modulating light and is appropriately positioned near the optical modulation sections 170a, 170b, and 170c. The electrode 200 has pad portions 201 near the third end face 13 and the fourth end face 14. The pad portions 201 function as connection terminals for electrically connecting the voltage supply circuit. The structure of the electrode 200 is not particularly limited. Although not shown, for example, an electrode for applying a bias voltage may also be provided.

[0031] The configuration of the optical device 10A in this embodiment will be described below.

[0032] The optical waveguide for propagating laser light emitted from the visible light laser source 301a will now be described. An optical input port 110a is located on the first end face 11. The optical input port 110a is the optical input port for the laser light emitted from the visible light laser source 301a. The laser light emitted from the visible light laser source 301a is incident on the optical input port 110a.

[0033] An input optical waveguide 111a is connected to the optical input port 110a. One end of the input optical waveguide 111a is connected to the optical input port 110a. The other end of the input optical waveguide 111a is connected to the optical input section of the optical branching unit 120a.

[0034] The optical branching unit 120a has a one-input, two-output structure with one optical input and two optical output sections, and is configured to split a single optical input signal into two optical output signals. The optical branching unit 120a is not particularly limited as long as it separates the light propagating through the optical waveguide, and for example, an MMI coupler (multimode interferometer coupler), a Y branch (Y-type waveguide), a directional coupler, etc., can be used.

[0035] One optical output of the optical branching section 120a is connected to one end of the monitoring optical waveguide 130a. The monitoring optical waveguide 130a bends midway and extends in the Y direction, and extends in the X direction near the third end face 13. The other end of the monitoring optical waveguide 130a is connected to the monitor port 131a located on the second end face 12. The monitor port 131a is a monitor light output port used when monitoring the laser light emitted from the visible light laser light source 301a. In this specification, the light output from the optical branching section 120a to the monitoring optical waveguide 130a is sometimes referred to as monitor light.

[0036] A tapered section 135a is positioned in the middle of the monitoring optical waveguide 130a to change the width of the optical waveguide (waveguide width). The tapered section 135a will be described later with reference to Figure 6.

[0037] The other optical output section of the optical branching section 120a is connected to one end of the modulation optical waveguide 140a. The other end of the modulation optical waveguide 140a is connected to the optical input section of the higher-order mode filter 150a. In this specification, the light output from the optical branching section 120a to the modulation optical waveguide 140a is sometimes referred to as display light. The display light output from the optical branching section 120a is red light, and after modulation by the optical modulation section 170a, it is combined with display light of other wavelengths and used, for example, as image projection light for XR glasses.

[0038] The modulation optical waveguide 140a includes a crossing waveguide 160a that intersects with the monitoring optical waveguide 130b, and a crossing waveguide 160b that intersects with the monitoring optical waveguide 130c. Crossing waveguides 160a and 160b will be described later with reference to Figure 8.

[0039] The higher-order mode filter 150a comprises an optical input section and an optical output section, and is configured to remove higher-order modes from the optical input section, so that only single-mode light is output from the optical output section. The higher-order mode filter 150a will be described later with reference to Figure 9.

[0040] The optical output section of the higher-order mode filter 150a is connected to one end of the modulation optical waveguide 151a. The other end of the modulation optical waveguide 151a is connected to the optical input section of the optical modulation section 170a. The modulation optical waveguides 140a and 151a constitute the first optical waveguide of the present invention. In the present invention, the optical branching section 120a and the optical modulation section 170a are connected via the first optical waveguide, and the optical branching section 120a is positioned before the optical modulation section 170a.

[0041] The optical modulation unit 170a is configured to modulate the light input to the optical input unit and output the modulated light from the optical output unit. For example, a Mach-Zehnder type optical waveguide having the structure of a Mach-Zehnder interferometer can be used for the optical modulation unit 170a.

[0042] As shown in Figure 2, the other end of the modulation optical waveguide 151a is connected to the optical branching section 171a, which serves as the optical input section of the optical modulation unit 170a. At the optical branching section 171a, the modulation optical waveguide 151a branches into two branch waveguides 172a and 173a. The two branch waveguides 172a and 173a extend parallel to each other in the X direction and are connected to the optical multiplexing section 174a, which serves as the optical output section of the optical modulation unit 170a. The two branch waveguides 172a and 173a merge at the optical multiplexing section 174a.

[0043] The optical modulation unit 170a controls the voltage supplied to the electrode 200 to apply an electric field to the branched waveguides 172a and 173a. The application of the electric field changes the refractive index of the branched waveguides 172a and 173a, respectively, and modulates the phase of the light based on this change in refractive index. The optical modulation unit 170a uses the interference effect to adjust the amplitude of the light after it is combined by the optical multiplexer 174a and outputs light of the desired intensity.

[0044] One end of the modulation optical waveguide 175a is connected to the optical output section of the optical modulation section 170a. The other end of the modulation optical waveguide 175a is connected to the optical input section of the optical multiplexing section 180. The modulation optical waveguide 175a constitutes the second optical waveguide of the present invention.

[0045] The optical multiplexer 180 has a multi-input, single-output structure comprising at least two optical inputs and one optical output, and is configured to combine two or more optical input signals into a single optical output signal. In the optical device 10A shown in Figures 1 and 2, the optical multiplexer 180 has a three-input, single-output structure and is configured to combine the light input from the modulation optical waveguide 175a, modulation optical waveguide 175b, and modulation optical waveguide 175c. However, the optical multiplexer 180 is not limited to this configuration, and for example, multiple optical multiplexers with a two-input, single-output structure may be connected in stages.

[0046] The optical multiplexer 180 is not particularly limited as long as it combines light propagating through the optical waveguide, and for example, an MMI coupler (multimode interferometer coupler), a Y branch (Y-type waveguide), a directional coupler, etc., can be used.

[0047] One end of the output optical waveguide 181 is connected to the optical output section of the optical multiplexer 180. The output optical waveguide 181 is bent approximately vertically at the bending section 182. The other end of the output optical waveguide 181 is connected to the optical output port 191 located on the fourth end face 14. The optical output port 191 is an optical output port that outputs the light combined by the optical multiplexer 180, and the light output from the optical output port 191 is emitted to the outside.

[0048] The optical waveguide for propagating laser light emitted from the visible light laser light source 301b will now be described. An optical input port 110b is located on the first end face 11. The optical input port 110b is the optical input port for the laser light emitted from the visible light laser light source 301b. The laser light emitted from the visible light laser light source 301b is incident on the optical input port 110b.

[0049] An input optical waveguide 111b is connected to the optical input port 110b. One end of the input optical waveguide 111b is connected to the optical input port 110b. The other end of the input optical waveguide 111b is connected to the optical input section of the optical branching unit 120b.

[0050] The optical branching unit 120b has a one-input, two-output structure with one optical input and two optical output sections, and is configured to split a single optical input signal into two optical output signals. The optical branching unit 120b is not particularly limited as long as it separates the light propagating through the optical waveguide, and for example, an MMI coupler (multimode interferometer coupler), a Y branch (Y-type waveguide), a directional coupler, etc., can be used.

[0051] One optical output of the optical branching section 120b is connected to one end of the monitoring optical waveguide 130b. The monitoring optical waveguide 130b bends midway and extends in the Y direction, and extends in the X direction near the third end face 13. The other end of the monitoring optical waveguide 130b is connected to the monitor port 131b located on the second end face 12. The monitor port 131b is a monitor light output port used when monitoring the laser light emitted from the visible light laser light source 301b. In this specification, the light output from the optical branching section 120b to the monitoring optical waveguide 130b is sometimes referred to as monitor light.

[0052] A tapered section 135b, which changes the waveguide width, is located in the middle of the monitoring optical waveguide 130b. The tapered section 135b will be described later with reference to Figure 6. In addition, a crossing waveguide 160a is located in the monitoring optical waveguide 130b, which intersects with the modulation optical waveguide 140a.

[0053] The other optical output section of the optical branching section 120b is connected to one end of the modulation optical waveguide 140b. The other end of the modulation optical waveguide 140b is connected to the optical input section of the higher-order mode filter 150b. In this specification, the light output from the optical branching section 120b to the modulation optical waveguide 140b is sometimes referred to as display light. The display light output from the optical branching section 120b is green light, and after modulation by the optical modulation section 170b, it is combined with display light of other wavelengths and used, for example, as image projection light for XR glasses.

[0054] The modulation optical waveguide 140b has a crossing waveguide 160c that intersects with the monitoring optical waveguide 130c. The crossing waveguide 160c will be described later with reference to Figure 7.

[0055] The higher-order mode filter 150b comprises an optical input section and an optical output section, and is configured to remove higher-order modes from the optical input section, so that only single-mode light is output from the optical output section. The higher-order mode filter 150b will be described later with reference to Figure 9.

[0056] The optical output section of the higher-order mode filter 150b is connected to one end of the modulation optical waveguide 151b. The other end of the modulation optical waveguide 151b is connected to the optical input section of the optical modulation section 170b. The modulation optical waveguides 140b and 151b constitute the first optical waveguide of the present invention. In the present invention, the optical branching section 120b and the optical modulation section 170b are connected via the first optical waveguide, and the optical branching section 120b is positioned before the optical modulation section 170b.

[0057] The optical modulation unit 170b is configured to modulate the light input to the optical input unit and output the modulated light from the optical output unit. For example, a Mach-Zehnder type optical waveguide having the structure of a Mach-Zehnder interferometer can be used for the optical modulation unit 170b.

[0058] As shown in Figure 2, the other end of the modulation optical waveguide 151b is connected to the optical branching section 171b, which serves as the optical input section of the optical modulation unit 170b. At the optical branching section 171b, the modulation optical waveguide 151b branches into two branch waveguides 172b and 173b. The two branch waveguides 172b and 173b extend parallel to each other in the X direction and are connected to the optical multiplexing section 174b, which serves as the optical output section of the optical modulation unit 170a. The two branch waveguides 172b and 173b merge at the optical multiplexing section 174b.

[0059] The optical modulation unit 170b controls the voltage supplied to the electrode 200 to apply an electric field to the branched waveguides 172b and 173b. The application of the electric field changes the refractive index of the branched waveguides 172b and 173b, respectively, and modulates the phase of the light based on this change in refractive index. The optical modulation unit 170b uses the interference effect to adjust the amplitude of the light after multiplexing by the optical multiplexer 174b and outputs light of the desired intensity.

[0060] One end of the modulation optical waveguide 175b is connected to the optical output section of the optical modulation section 170b. The other end of the modulation optical waveguide 175b is connected to the optical input section of the optical multiplexer 180. The modulation optical waveguide 175b constitutes the second optical waveguide of the present invention.

[0061] As described above, the optical multiplexer 180 combines the light input from the modulation optical waveguides 175a, 175b, and 175c. The light combined by the optical multiplexer 180 is emitted to the outside through the output optical waveguide 181 and the optical output port 191.

[0062] The optical waveguide for propagating laser light emitted from the visible light laser source 301c will now be described. An optical input port 110c is located on the first end face 11. The optical input port 110c is the optical input port for the laser light emitted from the visible light laser source 301c. The laser light emitted from the visible light laser source 301c is incident on the optical input port 110c.

[0063] An input optical waveguide 111c is connected to the optical input port 110c. One end of the input optical waveguide 111c is connected to the optical input port 110c. The other end of the input optical waveguide 111c is connected to the optical input section of the optical branching unit 120c.

[0064] The optical branching unit 120c has a one-input, two-output structure with one optical input and two optical output sections, and is configured to split a single optical input signal into two optical output signals. The optical branching unit 120c is not particularly limited as long as it separates the light propagating through the optical waveguide, and for example, an MMI coupler (multimode interferometer coupler), a Y branch (Y-type waveguide), a directional coupler, etc., can be used.

[0065] One optical output of the optical branching section 120c is connected to one end of the monitoring optical waveguide 130c. The monitoring optical waveguide 130c bends midway and extends in the Y direction, and extends in the X direction near the third end face 13. The other end of the monitoring optical waveguide 130c is connected to the monitor port 131c located on the second end face 12. The monitor port 131c is a monitor light output port used when monitoring the laser light emitted from the visible light laser light source 301c. In this specification, the light output from the optical branching section 120c to the monitoring optical waveguide 130c is sometimes referred to as monitor light.

[0066] A tapered section 135c is positioned in the middle of the monitoring optical waveguide 130c to change the waveguide width. The tapered section 135c will be described later with reference to Figure 6. In addition, the monitoring optical waveguide 130c is equipped with a crossing waveguide 160c that intersects with the modulation optical waveguide 140b, and a crossing waveguide 160b that intersects with the modulation optical waveguide 140a.

[0067] The other optical output section of the optical branching section 120c is connected to one end of the modulation optical waveguide 140c. The other end of the modulation optical waveguide 140c is connected to the optical input section of the higher-order mode filter 150c. In this specification, the light output from the optical branching section 120c to the modulation optical waveguide 140c is sometimes referred to as display light. The display light output from the optical branching section 120c is blue light, and after modulation by the optical modulation section 170c, it is combined with display light of other wavelengths and used, for example, as image projection light for XR glasses.

[0068] The higher-order mode filter 150c comprises an optical input section and an optical output section. It is configured to remove higher-order modes from the light input to the optical input section, and output only single-mode light from the optical output section. The higher-order mode filter 150c will be described later with reference to Figure 9.

[0069] The optical output section of the higher-order mode filter 150c is connected to one end of the modulation optical waveguide 151c. The other end of the modulation optical waveguide 151c is connected to the optical input section of the optical modulation section 170c. The modulation optical waveguide 140c and the modulation optical waveguide 151c constitute the first optical waveguide of the present invention. In the present invention, the optical branching section 120c and the optical modulation section 170c are connected via the first optical waveguide, and the optical branching section 120c is positioned before the optical modulation section 170c.

[0070] The optical modulation unit 170c is configured to modulate the light input to the optical input unit and output the modulated light from the optical output unit. For example, a Mach-Zehnder type optical waveguide having the structure of a Mach-Zehnder interferometer can be used for the optical modulation unit 170c.

[0071] As shown in Figure 2, the other end of the modulation optical waveguide 151c is connected to the optical branching section 171c, which serves as the optical input section of the optical modulation unit 170c. At the optical branching section 171c, the modulation optical waveguide 151c branches into two branch waveguides 172c and 173c. The two branch waveguides 172c and 173c extend parallel to each other in the X direction and are connected to the optical multiplexing section 174c, which serves as the optical output section of the optical modulation unit 170c. At the optical multiplexing section 174c, the two branch waveguides 172c and 173c merge into the modulation optical waveguide 151c.

[0072] The optical modulation unit 170c controls the voltage supplied to the electrode 200 to apply an electric field to the branched waveguides 172c and 173c. The application of the electric field changes the refractive index of the branched waveguides 172c and 173c, respectively, and modulates the phase of the light based on this change in refractive index. The optical modulation unit 170c uses the interference effect to adjust the amplitude of the light after multiplexing by the optical multiplexer 174c and outputs light of the desired intensity.

[0073] One end of the modulation optical waveguide 175c is connected to the optical output section of the optical modulation section 170c. The other end of the modulation optical waveguide 175c is connected to the optical input section of the optical multiplexer 180. The modulation optical waveguide 175c constitutes the second optical waveguide of the present invention.

[0074] As described above, the optical multiplexer 180 combines the light input from the modulation optical waveguides 175a, 175b, and 175c. The light combined by the optical multiplexer 180 is emitted to the outside through the output optical waveguide 181 and the optical output port 191.

[0075] In Figures 1 and 2, the optical input ports 110a, 110b, and 110c are arranged at equal intervals along the Y direction on the first end face 11, but these intervals do not necessarily have to be equal. Also, some of the optical input ports 110a, 110b, and 110c may be arranged on different end faces of the optical device 10A.

[0076] In Figures 1 and 2, the monitoring optical waveguides 130a, 130b, and 130c extend near the third end face 13, but they may also extend near the fourth end face 14. Furthermore, the monitor ports 131a, 131b, and 131c may be located on the third end face 13 or the fourth end face 14. Additionally, parts of the monitor ports 131a, 131b, and 131c may be located on different end faces of the optical device 10A. In Figures 1 and 2, the optical output port 191 is located on the fourth end face 14, but it may be located on other end faces (e.g., the second end face 12), as shown in the derivative examples described later.

[0077] <Cross-sectional structure of optical devices> The cross-sectional structure of the optical device 10A will be described with reference to Figures 3 to 5. Figure 3 is a cross-sectional view along line AA in Figure 1. Figure 4 is a cross-sectional view along line BB in Figure 1. Figure 5 is a cross-sectional view along line CC in Figure 1.

[0078] As shown in Figures 3 to 5, the optical device 10A includes a substrate 101, an optical functional layer 102, and a protective layer 106. The optical functional layer 102 is composed of, for example, an optical waveguide layer 103, a first buffer layer 104, and a second buffer layer 105. The optical device 10A has a multilayer structure in which the optical waveguide layer 103, the first buffer layer 104, the second buffer layer 105, and the protective layer 106 are stacked in this order on the substrate 101.

[0079] As shown in Figures 3 and 5, the electrode 200 and pad portion 201 are positioned between the second buffer layer 105 and the protective layer 106. Figure 3 shows the drive electrode 200S and the reference electrode 200G as the electrode 200.

[0080] The substrate 101 is a component that ensures the physical stability and durability of the entire optical device 10A. From the viewpoint of confining light in the optical waveguide formed in the optical functional layer 102 and improving optical propagation efficiency, it is preferable to use a material for the substrate 101 that has a lower refractive index than the material of the optical waveguide layer 103. As the substrate 101, for example, a substrate made of a material containing aluminum oxide (sapphire substrate), a Si substrate, a thermal silicon oxide substrate, etc., can be used.

[0081] The optical waveguide layer 103 functions as a waveguide core film that forms an optical waveguide. The optical waveguide layer 103 is a ferroelectric thin film made of a crystal represented by the chemical formula ABX3. The material of the optical waveguide layer 103 can be a material that exhibits an electro-optic effect. Examples of materials that exhibit an electro-optic effect include oxide ferroelectrics such as lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and barium titanate (BaTiO3). An optical device 10A using lithium niobate for the optical waveguide layer 103 is sometimes called an LN optical device, and an optical modulator on which an LN optical device is mounted is sometimes called an LN optical modulator.

[0082] When a sapphire single crystal substrate or a silicon single crystal substrate is used as the substrate 101, the lithium niobate film constituting the optical waveguide layer 103 can be formed as an epitaxial film on the upper surface of the substrate 101. The crystal orientation of the substrate 101 is not particularly limited, but since it serves as the base for the optical waveguide layer 103, it is preferable that it has the same symmetry as the optical waveguide layer 103. Specifically, the lithium niobate film has triple symmetry, and when a c-axis oriented lithium niobate film is used as the optical waveguide layer 103, it is preferable to use a c-plane substrate 101 if it is a sapphire single crystal substrate, or a (111)-plane substrate 101 if it is a silicon single crystal substrate.

[0083] An epitaxial film is a film in which crystals grow based on the crystal orientation of the underlying substrate 101, and are oriented to a specific crystal orientation that matches the crystal structure of the substrate 101. Whether the optical waveguide layer 103 is an epitaxial film relative to the substrate 101 can be proven, for example, by performing peak intensity and pole analysis at the orientation position in 2θ-θ X-ray diffraction.

[0084] Specifically, when measurements are performed by 2θ-θX-ray diffraction, the peak intensities of all planes other than the target plane must be 10% or less, preferably 5% or less, of the maximum peak intensity of the target plane. For example, in the case of an epitaxial film made of a c-axis oriented lithium niobate film, the peak intensities of planes other than the (00L) plane are 10% or less, preferably 5% or less, of the maximum peak intensity of the (00L) plane. Here, (00L) is a general designation for equivalent planes such as (001) and (002).

[0085] Furthermore, pole analysis requires the observation of poles. Confirming peak intensity at a specific orientation position only evaluates crystal orientation in one direction. Therefore, even if it can be confirmed that the peak intensity is below a predetermined value, if the crystal orientation is not aligned in the plane, the X-ray intensity will not increase at a specific angular position, and poles will not be observed. Since LiNbO3 has a trigonal crystal structure, there are three poles in LiNbO3(014) in a single crystal.

[0086] In the case of lithium niobate films, it is known that epitaxial growth occurs in a so-called twinned state, where crystals rotated 180° around the c-axis are symmetrically bonded. In this case, since three poles are symmetrically bonded in pairs, six poles are observed. Furthermore, when a lithium niobate film is formed on a (100)-plane silicon single crystal substrate, the substrate is symmetrical four times, so 4 × 3 = 12 poles are observed. In this invention, lithium niobate films grown epitaxially in a twinned state are also included in the definition of epitaxial films.

[0087] The composition of lithium niobate is Li x NbA y O zThe values ​​are as follows: x is 0.5 to 1.2, preferably 0.9 to 1.05. y is 0 to 0.5. z is 1.5 to 4.0, preferably 2.5 to 3.5. Element A is an element other than Li, Nb, or O. Examples of element A include K, Na, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Zn, Sc, Ce, etc., and a combination of two or more of these elements is also acceptable.

[0088] The optical waveguide layer 103 is not limited to one formed by epitaxial growth, but may also be a thin film bonded to the upper surface of the substrate 101.

[0089] The optical waveguide layer 103 is composed of a slab layer 103a having a predetermined thickness and a ridge portion 103b protruding from the upper surface of the slab layer 103a. As shown in Figures 3 and 4, the ridge portion 103b is positioned where the optical waveguide is formed. The ridge portion 103b confines light inside and forms an optical waveguide through which the light propagates. The ridge portion 103b shown in Figure 3 forms branched waveguides 172c and 173c. The ridge portion 103b shown in Figure 4 forms a monitor optical waveguide 130c. In the cross-section of Figure 5, the ridge portion 103b is not provided, and the optical waveguide layer 103 is composed of a slab layer 103a having a predetermined thickness.

[0090] The ridge portion 103b may be a protruding portion formed by etching the optical waveguide layer 103, or it may be formed by attaching the same material as the slab layer 103a to the upper surface of the slab layer 103a. The shape of the ridge portion 103b is not particularly limited, but in this case it is formed to have a rectangular cross-section.

[0091] By reducing the distance between adjacent ridge portions 103b, the electric field efficiency applied to the optical waveguide formed by the ridge portions 103b can be improved.

[0092] Instead of forming an optical waveguide with the ridge portion 103b, an optical waveguide may be formed by creating a region with a high refractive index within the optical waveguide layer 103. For example, a region with a locally high refractive index may be created within the optical waveguide layer 103 by a Ti diffusion method or a proton exchange method, and this region may be used as an optical waveguide.

[0093] As shown in Figures 3 to 5, the first buffer layer 104 is positioned on the upper surface of the slab layer 103a of the optical waveguide layer 103. Near the formation locations of the ridge portions 103b, the first buffer layer 104 is filled between adjacent ridge portions 103b and is provided to cover the upper surface of the slab layer 103a and the sides of the ridge portions 103b.

[0094] As shown in Figures 3 to 5, the second buffer layer 105 is positioned on the upper surface of the first buffer layer 104. Near the formation location of the ridge portion 103b, the second buffer layer 105 is provided to cover the upper surface of the first buffer layer 104 and the upper surface of the ridge portion 103b.

[0095] The first buffer layer 104 and the second buffer layer 105 are made of a dielectric material with a lower refractive index than the optical waveguide layer 103. The first buffer layer 104 and the second buffer layer 105 have the role of preventing visible light propagating through the optical waveguide layer 103 from being absorbed by the electrode 200.

[0096] For example, silicon dioxide (SiO2), aluminum oxide (Al2O3), lanthanum oxide (La2O3), or composites of these oxides can be used as materials for the first buffer layer 104 and the second buffer layer 105. Examples of the oxide composites include LaAlSiInO. The materials for the first buffer layer 104 and the second buffer layer 105 may be different. In this preferred embodiment, silicon dioxide is used as the material for the first buffer layer 104 and LaAlSiInO is used as the material for the second buffer layer 105. Alternatively, the materials for the first buffer layer 104 and the second buffer layer 105 may be the same, or the first buffer layer 104 and the second buffer layer 105 may be arranged in an integrated state.

[0097] As shown in Figures 3 and 5, the electrode 200 and pad portion 201 are arranged on the upper surface of the second buffer layer 105. In this embodiment, a configuration using a Z-cut lithium niobate film as the optical waveguide layer 103 is shown as an example. In this case, since the electro-optic effect is strongly expressed in the Z direction, it is preferable to arrange the electrode 200 directly above the ridge portion 103b that forms the optical waveguide, as shown in Figure 3. However, an X-cut lithium niobate film may also be used as the optical waveguide layer 103. In this case, since the electro-optic effect is strongly expressed in the Y direction, it is preferable to arrange the electrode 200 to the side of the ridge portion 103b that forms the optical waveguide.

[0098] As shown in Figures 3 and 4, the protective layer 106 is positioned to cover the upper surface of the second buffer layer 105 and the upper surface of the electrode 200. The protective layer 106 protects the upper surface of the second buffer layer 105 and the upper surface of the electrode 200, and in particular prevents damage to the electrode 200. For example, silicon oxide (SiO2) or silicon nitride (SiN) can be used as the material for the protective layer 106. The material of the protective layer 106 may be the same as or different from that of the first buffer layer 104 or the second buffer layer 105.

[0099] The protective layer 106 covers the entire upper surface of the optical device 10A, including the upper surface of the second buffer layer 105 and the upper surface of the electrode 200. However, as shown in Figure 5, a portion of the pad portion 201 is not covered by the protective layer 106, and the upper surface 201a of the pad portion 201 is exposed to the outside. Through this exposed upper surface 201a, the pad portion 201 can be electrically connected to an external power supply circuit, etc. Specifically, the protective layer 106 covers the entire side surface and a portion of the upper surface 201a of the pad portion 201, while being cut away at the upper surface 201a of the pad portion 201. As a result, a gap is formed between the ends 106a of the protective layer 106, and the upper surface 201a of the pad portion 201 is exposed to the outside through this gap. Alternatively, a metal layer may be formed on the upper part of the pad portion 201. This can improve the strength of the physical connection with the external power supply circuit.

[0100] The height of the slab layer 103a (height H1 in Figures 3 to 5) is not particularly limited, but is preferably 0.1 μm to 0.3 μm, and is set to 0.15 μm as an example. The ridge portion 103b is preferably set to an appropriate size, as if it is too small, light will not propagate properly, and if it is too large, the propagating light will be multimode. The height from the bottom surface of the slab layer 103a to the top surface of the ridge portion 103b (height H2 in Figures 3 to 5) is preferably 0.5 μm to 1.5 μm, and is set to 0.7 μm as an example. The shape of the ridge portion 103b is not particularly limited, but can be a trapezoid with a base angle θ (angle θ in Figures 3 and 4) of 70° to 90°.

[0101] The height of the second buffer layer 105 (height H3 in Figures 3 to 5) is not particularly limited, but can be set to approximately the same height as the above height H2, and as an example, it is set to 0.7 μm. The height of the electrode 200 and pad portion 201 (height H4 in Figures 3 and 5) is not particularly limited, but is preferably 0.1 μm to 5.0 μm, and as an example, it is set to 2.0 μm. The height of the protective layer 106 (height H5 in Figures 3 to 5) is not particularly limited, but is preferably 0.5 μm to 0.7 μm.

[0102] The distance between the centers of adjacent ridge portions 103b (width W1 in Figure 3) is not particularly limited, but is preferably 2.0 μm to 12 μm, and is set to 4.0 μm as an example. The width of the electrode 200 is not particularly limited, but the width of the drive electrode 200S (width W2 in Figure 3) is preferably 1.0 to 4.0 μm, and is set to 3.0 μm as an example.

[0103] The distance between adjacent electrodes 200 is not particularly limited, but the distance between the sides of adjacent electrodes 200 (width W4 in Figure 3) is preferably 1.0 μm to 10 μm, and is set to 2.0 μm as an example. The upper surface 201a of the pad portion 201 may be exposed to the outside as an electrical connection terminal, and the distance between the end 106a of the protective layer 106 and the side surface of the pad portion 201 (width W5 in Figure 5) is set to 10 μm as an example.

[0104] The width of the ridge portion 103b corresponds to the width of the optical waveguide. In this embodiment, the width of the ridge portion 103b that forms the monitoring optical waveguides 130a, 130b, and 130c is set to be at least greater than the width of the ridge portion 103b that forms the optical waveguides 170a, 170b, and 170c.

[0105] Figure 3 shows cross-sections of ridges 103b1 and 103b2, which form the branch waveguides 172c and 173c of the optical modulation section 170c, as ridges 103b. The width WA of the upper surface of ridges 103b (see Figure 3) is preferably 1.0 μm or less, and is set to 0.8 μm as an example. The widths of the ridges 103b that form the branch waveguides 172a and 173a of the optical modulation section 170a, and the widths of the ridges 103b that form the branch waveguides 172b and 173b of the optical modulation section 170b are set similarly.

[0106] Figure 4 shows a cross-section of the ridge portion 103b3, which forms the monitoring optical waveguide 130c, as the ridge portion 103b. The width WB of the upper surface of the ridge portion 103b3 (see Figure 4) is preferably 2.0 μm or more, and is set to 3.0 μm as an example. The width of the ridge portions 103b that form the monitoring optical waveguides 130a and 130b is set similarly.

[0107] The following describes a specific example of the waveguide width of the optical device 10A in this embodiment, with reference to Figure 2.

[0108] The waveguide widths of the input optical waveguides 111a, 111b, and 111c connected to the optical input ports 110a, 110b, and 110c are set to the width WA (e.g., 0.8 μm) shown in Figure 3. At the optical branching sections 120a, 120b, and 120c, the optical waveguides branch into monitoring optical waveguides 130a, 130b, and 130c, and modulation optical waveguides 140a, 140b, and 140c.

[0109] In the monitoring optical waveguides 130a, 130b, and 130c, the waveguide width is changed at the tapered section 135a. The width of the optical waveguide from the optical branching sections 120a, 120b, and 120c to the tapered sections 135a, 135b, and 135c is set to the width WA (e.g., 0.8 μm) shown in Figure 3. In the tapered sections 135a, 135b, and 135c, the waveguide width increases in the direction of optical propagation. The width of the optical waveguide from the tapered sections 135a, 135b, and 135c to the monitor ports 131a, 131b, and 131c is set to the width WB (e.g., 3.0 μm) shown in Figure 4.

[0110] As described later, the monitoring optical waveguides 130a, 130b, and 130c may be configured such that the waveguide width changes in the crossing waveguides 160a, 160b, and 160c. In the crossing waveguides 160a, 160b, and 160c, the waveguide width of the monitoring optical waveguides 130a, 130b, and 130c is set to be greater than or equal to the width WB (e.g., 3.0 μm) shown in Figure 4.

[0111] The waveguide widths of the modulation optical waveguides 140a, 140b, 140c and subsequent waveguides are set to the width WA (e.g., 0.8 μm) shown in Figure 3. More specifically, the waveguide widths of the modulation optical waveguides 140a, 140b, 140c are set to the width WA (e.g., 0.8 μm) shown in Figure 3. The waveguide widths of the modulation optical waveguides 151a, 151b, 151c are set to the width WA (e.g., 0.8 μm) shown in Figure 3. The waveguide widths of the branched waveguides 172a, 173a, 172b, 173b, 172c, 173c are set to the width WA (e.g., 0.8 μm) shown in Figure 3. The waveguide widths of the modulation optical waveguides 175a, 175b, 175c are set to the width WA (e.g., 0.8 μm) shown in Figure 3. The waveguide width of the output optical waveguide 181 is set to the width WA (e.g., 0.8 μm) shown in Figure 3.

[0112] As will be described later, the modulation optical waveguides 140a, 140b, and 140c are configured such that the waveguide width changes in the crossing waveguides 160a, 160b, and 160c. In the crossing waveguides 160a, 160b, and 160c, the waveguide width of the modulation optical waveguides 140a, 140b, and 140c is set to be larger than the width WA (e.g., 0.8 μm) shown in Figure 3.

[0113] In this way, by expanding the waveguide width of the monitor optical waveguides 130a, 130b, and 130c with tapered sections 135a, 135b, and 135c to allow for multimode propagation of light waves, propagation losses due to scattering and absorption can be reduced, and the amount of light propagation can be increased. As a result, the output light intensity of the monitor ports 131a, 131b, and 131c can be increased.

[0114] <Tapered section> The tapered sections 135a, 135b, and 135c will be described with reference to Figure 6. Figure 6 is a schematic plan view of the tapered section 135a shown in Figures 1 and 2.

[0115] As shown in Figure 6, the tapered section 135a is positioned in the middle of the monitoring optical waveguide 130a and is configured to change the waveguide width of the monitoring optical waveguide 130a. The tapered section 135a has a narrow end 135a1 located on the optical branching section 120a side, a wide end 135a2 located on the monitor port 131a side, and a widening section 135a3 positioned between the narrow end 135a1 and the wide end 135a2.

[0116] The width of the narrow end 135a1 is the same as the width WA (e.g., 0.8 μm) of the optical waveguide from the optical branching section 120a to the tapered section 135a. The width of the wide end 135a2 is the same as the width WB (e.g., 3.0 μm) of the waveguide from the tapered section 135a to the monitor port 131a. The width of the widening section 135a3 increases smoothly from the narrow end 135a1 to the wide end 135a2. With this configuration, the tapered section 135a smoothly expands the width of the monitor optical waveguide 130a in the direction of monitor light propagation.

[0117] The tapered portion 135a can be placed at any position in the monitoring optical waveguide 130a, but it is preferable to place it near the optical branching portion 120a. The length L1 (see Figure 6) between the optical branching portion 120a and the narrow end portion 135a1 is preferably, for example, 50 μm to 500 μm. By placing the tapered portion 135a near the optical branching portion 120a, the waveguide width can be increased in most areas of the monitoring optical waveguide 130a.

[0118] The length L2 of the widened portion 135a3 (see Figure 6) is preferably set to an appropriate distance considering the reduction of propagation loss and the efficiency of the manufacturing process. The length L2 of the widened portion 135a3 is not particularly limited, but is preferably 50 μm to 150 μm, and is set to 100 μm as an example.

[0119] Here, the structure of the tapered section 135a was illustrated and explained in Figure 6, but the tapered sections 135b and 135c have a similar structure.

[0120] By widening the waveguide width of the monitor optical waveguides 130a, 130b, and 130c with tapered sections 135a, 135b, and 135c, the monitor light propagating through the monitor optical waveguides 130a, 130b, and 130c becomes multimode. This reduces the propagation loss of the monitor light in the monitor optical waveguides 130a, 130b, and 130c, allowing sufficient light intensity of monitor light to be emitted from the monitor ports 131a, 131b, and 131c.

[0121] <cross waveguide> The crossing waveguides 160a, 160b, and 160c will be described with reference to Figures 7 and 8. Figure 7 is a schematic plan view of the crossing waveguide 160c in Figures 1 and 2. Figure 8 is a schematic plan view of the connected crossing waveguides 160a, 160b, and 160c in Figures 1 and 2.

[0122] In the optical device 10A of this embodiment, the monitoring optical waveguides 130a, 130b, and 130c extend in the Y direction midway and reach the vicinity of the third end face 13. This configuration results in intersections between the monitoring optical waveguide 130b and the modulation optical waveguide 140a, between the monitoring optical waveguide 130c and the modulation optical waveguide 140a, and between the monitoring optical waveguide 130c and the modulation optical waveguide 140b.

[0123] At each intersection, propagation loss due to scattering and other factors increases, which may result in a decrease in the output light intensity of monitor ports 131a, 131b, 131c and optical output port 191. Hereafter, such loss may be referred to as "crossover loss."

[0124] In the optical device 10A of this embodiment, cross waveguides 160a, 160b, and 160c are arranged at each intersection, taking into consideration the crossing losses that may occur at each intersection.

[0125] The crossing waveguide 160c shown in Figure 7 will now be described. As shown in Figure 7, the crossing waveguide 160c is located at the intersection of the monitoring optical waveguide 130c and the modulation optical waveguide 140b, and is configured to change the waveguide width of the monitoring optical waveguide 130c and the modulation optical waveguide 140b. At the intersection, it is preferable to cross the monitoring optical waveguide 130c and the modulation optical waveguide 140b approximately perpendicularly in order to reduce the effect of crossing loss.

[0126] The cross waveguide 160c has four tapered sections 161c, 162c, 163c, and 164c and a cross intersection section 165c.

[0127] The tapered portion 161c constitutes part of the optical waveguide that propagates the display light. The tapered portion 161c is positioned on the optical branching portion 120b side with respect to the intersection. The tapered portion 161c has a narrow end 161c1 located on the optical branching portion 120b side, a wide end 161c2 located on the optical modulation portion 170b side, and a widening portion 161c3 positioned between the narrow end 161c1 and the wide end 161c2.

[0128] The width of the narrow end 161c1 is the same as the width WA (e.g., 0.8 μm) of the modulation optical waveguide 140b. The width WC of the wide end 161c2 is set to be larger than the width WA of the narrow end 161c1. The width WC of the wide end 161c2 is preferably 2.0 μm to 5.0 μm, and is set to 3.6 μm as an example.

[0129] The width of the widened section 161c3 increases smoothly from the narrow end 161c1 to the wide end 161c2. This configuration allows the tapered section 161c to smoothly expand the width of the modulation optical waveguide 140b in the direction of light propagation.

[0130] The tapered portion 162c constitutes part of the optical waveguide that propagates the display light. The tapered portion 162c is positioned on the optical modulation section 170b side with respect to the intersection. The tapered portion 162c has a wide end 162c1 located on the optical branching section 120b side, a narrow end 162c2 located on the optical modulation section 170b side, and a narrowed portion 162c3 positioned between the wide end 162c1 and the narrow end 162c2.

[0131] The width of the wide end 162c1 is the same as the width WC of the wide end 161c2. The width of the narrow end 162c2 is the same as the width WA (e.g., 0.8 μm) of the modulation optical waveguide 140b. The width of the tapered section 162c3 smoothly decreases from the wide end 162c1 to the narrow end 162c2. With this configuration, the tapered section 162c smoothly reduces the width of the modulation optical waveguide 140b in the direction of propagation of the displayed light.

[0132] The length L3 of the widening section 161c3 (see Figure 7) and the length L4 of the narrowing section 162c3 (see Figure 7) may be the same or different. The length L3 of the widening section 161c3 and the length L4 of the narrowing section 162c3 are not particularly limited, but are preferably 50 μm to 150 μm, and as an example, both length L3 and length L4 are set to 100 μm.

[0133] The tapered portion 163c constitutes part of the optical waveguide that propagates the monitor light. The tapered portion 163c is positioned on the optical branching portion 120c side with respect to the intersection. The tapered portion 163c has a narrow end 163c1 located on the optical branching portion 120c side, a wide end 163c2 located on the monitor port 131c side, and a widening portion 163c3 positioned between the narrow end 163c1 and the wide end 163c2.

[0134] The width of the narrow end 163c1 is the same as the width WB (e.g., 3.0 μm) of the monitoring optical waveguide 130c. The width WC of the wide end 163c2 is set to be greater than or equal to the width WB of the narrow end 163c1. The width WC of the wide end 163c2 is preferably 3.0 μm to 5.0 μm, and is set to 3.6 μm as an example.

[0135] The width of the widened section 163c3 increases smoothly from the narrow end 163c1 to the wide end 163c2. This configuration allows the tapered section 163c to smoothly expand the width of the monitoring optical waveguide 130c in the direction of monitoring light propagation.

[0136] The tapered portion 164c constitutes part of the optical waveguide that propagates the monitor light. The tapered portion 164c is positioned on the monitor port 131c side with respect to the intersection. The tapered portion 164c has a wide end 164c1 located on the optical branching portion 120c side, a narrow end 164c2 located on the monitor port 131c side, and a narrowed portion 164c3 positioned between the wide end 164c1 and the narrow end 164c2.

[0137] The width of the wide end 164c1 is the same as the width WC of the wide end 163c2. The width of the narrow end 164c2 is the same as the width WB (e.g., 3.0 μm) of the monitoring optical waveguide 130c. The width of the tapered section 164c3 smoothly decreases from the wide end 164c1 to the narrow end 164c2. With this configuration, the tapered section 164c smoothly reduces the width of the monitoring optical waveguide 130b in the direction of monitoring light propagation.

[0138] The length L5 of the widening section 163c3 (see Figure 7) and the length L6 of the narrowing section 164c3 (see Figure 7) may be the same or different. The length L5 of the widening section 163c3 and the length L6 of the narrowing section 164c3 are not particularly limited, but are preferably 50 μm to 150 μm, and as an example, both lengths L5 and L6 are set to 100 μm.

[0139] The cross-shaped intersection 165c is formed in a cross shape and constitutes the intersection center of the monitoring optical waveguide 130c and the modulation optical waveguide 140b. The cross-shaped intersection 165c connects the wide end 161c2 of the tapered section 161c and the wide end 162c1 of the tapered section 162c. The cross-shaped intersection 165c connects the wide end 163c2 of the tapered section 163c and the wide end 164c1 of the tapered section 164c.

[0140] The crossing waveguide 160c is configured to expand the waveguide width of the monitor light and the display light at the intersection of the monitor optical waveguide 130c and the modulation optical waveguide 140b. The monitor light and display light pass through the crossing waveguide 160c in a multimode state. This reduces crossover loss and increases the amount of light propagation, thereby increasing the output light intensity of the monitor port 131c and the optical output port 191.

[0141] Here, the configuration of the cross waveguide 160c was explained with reference to Figure 7, but the cross waveguides 160a and 160b can be configured in a similar manner.

[0142] Furthermore, if multiple crossing waveguides are arranged in the same optical waveguide, a portion of the tapered section may be omitted and the crossing waveguides may be connected to each other. In this embodiment, as shown in Figure 8, the crossing waveguide 160a and the crossing waveguide 160b are connected to each other.

[0143] The cross waveguide 160a is located at the intersection of the monitoring optical waveguide 130b and the modulation optical waveguide 140a. As shown in Figure 8, the cross waveguide 160a has three tapered sections 161a, 163a, and 164a and a cross intersection section 165a.

[0144] The cross waveguide 160b is located at the intersection of the monitoring optical waveguide 130c and the modulation optical waveguide 140a. As shown in Figure 8, the cross waveguide 160b has three tapered sections 162b, 163b, and 164b and a cross intersection section 165b.

[0145] The cross waveguide 160a does not have a tapered section on the optical modulation section 170a side of the intersection. The cross waveguide 160b does not have a tapered section on the optical branching section 120a side of the intersection. Instead, the cross intersection 165a of the cross waveguide 160a and the cross intersection 165b of the cross waveguide 160b are connected by a connecting section 166. The width WD of the connecting section 166 is preferably, for example, 2.0 μm to 5.0 μm, and is set to 3.6 μm as an example.

[0146] When multiple intersecting waveguides are arranged on the same optical waveguide, the tapered sections between the intersecting waveguides may be omitted and they may be connected by a connecting section 166. This shortens the waveguide length of the tapered section, thereby reducing optical loss due to propagation.

[0147] <Higher-order mode filter> The higher-order mode filters 150a, 150b, and 150c will be explained with reference to Figure 9. Figure 9 is a schematic plan view of the higher-order mode filter 150a in Figures 1 and 2. Here, the configuration of the higher-order mode filter 150a is illustrated and explained in Figure 9, but the higher-order mode filters 150b and 150c have a similar configuration.

[0148] The higher-order mode filter 150a is positioned between the cross waveguide 160b and the optical modulation section 170a.

[0149] In the modulation optical waveguide 140a, the display light after passing through the cross waveguides 160a and 160b is multimode. Furthermore, depending on the mounting precision of the visible light laser sources 301a, 301b, and 301c, the light may become multimode upon incidence. To improve the modulation efficiency of the optical modulation unit 170a, it is necessary to remove the higher-order modes of the display light and convert it to single-mode.

[0150] The higher-order mode filter 150a is configured to remove higher-order modes from the display light and convert it to single-mode light. More specifically, the higher-order mode filter 150a has a curved waveguide 150a1 formed in a semi-circular arc shape in plan view, and curved sections 150a2 and 150a3 that connect the curved waveguide 150a1 to the modulation optical waveguides 140a and 151a. The curved sections 150a2 and 150a3 are structured to curve the optical waveguide by 90°. The semi-circular curved waveguide 150a1 is connected between the curved sections 150a2 and 150a3.

[0151] Higher-order modes of light are susceptible to loss due to their structural characteristics when passing through a curved optical waveguide. By passing multimode light through a curved optical waveguide, it is possible to selectively pass only specific modes and convert them to single modes. The higher-order mode filter 150a is configured to remove higher-order modes from the display light using the curved waveguide 150a1 and convert it to single modes.

[0152] In order to remove the multimode of the display light that has passed through the curved waveguide 150a1 and convert it to a single mode, it is preferable to appropriately set the shape of the curved waveguide 150a1.

[0153] The width WE of the curved waveguide 150a1 is preferably 0.4 μm to 0.8 μm, and is set to, for example, 0.6 μm.

[0154] The curvature (radius of curvature R) of the curved waveguide 150a1 is preferably set individually according to the wavelength of the display light (for example, the three primary colors of red, green, and blue). The radius of curvature R refers to the distance from the center of the semicircular arc to the center of the optical waveguide. When the display light is red light (wavelength 637 nm), the radius of curvature R of the curved waveguide 150a1 is preferably 40 μm to 80 μm, for example, set to 60 μm. When the display light is green light (wavelength 520 nm), the radius of curvature R of the curved waveguide 150a1 is preferably 60 μm to 100 μm, for example, set to 80 μm. When the display light is blue light (wavelength 455 nm), the radius of curvature R of the curved waveguide 150a1 is preferably 100 μm to 140 μm, for example, set to 120 μm.

[0155] In this embodiment, the higher-order mode filter 150a is configured to remove higher-order modes of red light, the higher-order mode filter 150b is configured to remove higher-order modes of green light, and the higher-order mode filter 150c is configured to remove higher-order modes of blue light.

[0156] By effectively removing higher-order modes contained in the display light of each wavelength using higher-order mode filters 150a, 150b, and 150c, and converting the display light modulated by the optical modulation units 170a, 170b, and 170c into single-mode light, the modulation efficiency of the optical modulation units 170a, 170b, and 170c can be improved.

[0157] <Manufacturing method for light source modules> The manufacturing method for the light source module 1A will be described.

[0158] When manufacturing the light source module 1A, first, the optical device 10A is fabricated and prepared. The optical device 10A can be fabricated by known methods after designing the optical waveguide pattern described above. Specifically, a substrate 101 processed to a predetermined thickness is prepared, and the optical functional layer 102, electrodes 200, and protective layer 106 are laminated on the substrate 101. For example, when forming a lithium niobate film as an epitaxial film on a single crystal substrate made of sapphire or the like, the epitaxial film is formed by sputtering or CVD in accordance with the crystal orientation of the single crystal substrate. The ridge portion 103b can be formed by dry etching after creating a pattern (mask) on the lithium niobate film using photolithography, for example.

[0159] Next, the relative positions of the visible light laser sources 301a, 301b, and 301c with respect to the optical device 10A are adjusted and fixed by active alignment.

[0160] Figure 10 is a diagram illustrating the active alignment performed in the manufacturing process of the light source module 1A in this embodiment. Figure 10 schematically shows the state in which active alignment of the visible light laser light source 301a is being performed.

[0161] When performing active alignment of the visible light laser light source 301a, the visible light laser light source 301a is placed near the optical input port 110a, and the optical detection device 310 is placed near the monitor port 131a. The optical detection device 310 is a device that detects the amount of light (light intensity), and for example, a photodetector that outputs an electrical signal corresponding to the amount of light received can be used. The output light amount of the monitor port 131a is detected using the optical detection device 310.

[0162] Visible light incident from the optical input port 110a propagates through the input optical waveguide 111a, the optical branching section 120a, and the monitoring optical waveguide 130a, and is emitted as monitor light from the monitor port 131a. In the optical device 10A, the optical branching section 120a is positioned before the optical modulation section 170a.

[0163] If the monitor light is configured to pass through the optical modulation section 170a, the initial phase difference between the branched waveguides 172a and 173a in the optical modulation section 170a may prevent the acquisition of sufficient monitor light. In this case, it is necessary to apply a voltage to the optical modulation section 170a to adjust the phase of the light propagating through the branched waveguides 172a and 173a.

[0164] In contrast, in the optical device 10A of this embodiment, the visible light separated by the optical branching unit 120a is emitted as monitor light from the monitor port 131a without passing through the optical modulation unit 170a. Therefore, in this embodiment, there is no need to supply power to the optical device 10A to perform phase adjustment in the optical modulation unit 170a, and sufficient light intensity of monitor light can be emitted from the monitor port 131a.

[0165] The visible light emitted from the visible light laser light source 301a is incident on the optical input port 110a, and the light emitted from the monitor port 131a is incident on the optical detection device 310. The optical detection device 310 detects the output light intensity of the monitor port 131a and outputs the detection result. Based on the detection result of the optical detection device 310, the relative position of the visible light laser light source 301a with respect to the optical device 10A is adjusted so that the output light intensity of the monitor port 131a is above a certain level, ideally at its maximum. Here, the relative position refers to the xyz coordinate position of the visible light laser light source 301a with respect to the optical device 10A, and the orientation of the visible light laser light source 301a (angle of incidence of visible light on the optical device 10A).

[0166] Figure 11 is a diagram illustrating the concept of active alignment performed in this embodiment. Figure 11 shows the vicinity of the optical input port 110a of the first end face 11.

[0167] As shown in Figure 11, visible light emitted from the visible light laser source 301a is directed towards the vicinity of the optical input port 110a. The visible light has an illumination range (spot S) with a certain spread. The optical axis of the visible light, which is laser light, is located at the center of the spot S. Typically, the output light intensity of the monitor port 131a is maximized by aligning the center position CE of the optical input port 110a with the optical axis of the visible light.

[0168] In active alignment, the output light intensity of the monitor port 131a detected by the optical detection device 310 is detected in real time, and the relative position of the visible light laser light source 301a with respect to the optical device 10A is determined so that the output light intensity is maximized. For example, the position in which the output light intensity of the monitor port 131a is maximized is determined by moving the visible light laser light source 301a in the Y and Z directions while keeping the emitting surface of the visible light laser light source 301a and the first end surface 11 facing each other at a constant distance.

[0169] When the output light intensity of the monitor port 131a is at its maximum, the optical axis of the visible light emitted from the visible light laser source 301a coincides with the center position of the optical input port 110a. In this state, the visible light laser source 301a is fixed to the optical device 10A. For example, the subcarrier 302a on which the visible light laser source 301a is mounted is joined to the substrate 101 of the optical device 10A.

[0170] In this way, active alignment using monitor light optimizes the incidence efficiency of visible light into the optical input port 110a. Furthermore, precise positioning of the visible light laser light source 301a can be performed, improving the overall operating efficiency and optical performance of the optical device 10A.

[0171] This section describes active alignment for visible light laser light source 301a, but active alignment can be performed in the same manner for visible light laser light sources 301b and 301c.

[0172] <Anti-reflective device> The visible light emitted from the visible light laser light sources 301a, 301b, and 301c is split by the optical branching sections 120a, 120b, and 120c, and simultaneously emitted from the monitor ports 131a, 131b, 131c and the optical output port 191.

[0173] Monitor light is required when performing active alignment, but it is not necessary when using the display light emitted from optical output port 191. However, even when monitor light is not required, monitor light will still be emitted from monitor ports 131a, 131b, and 131c.

[0174] Figure 12 illustrates the configuration in which the anti-reflective device 320 is placed near the monitor ports 131a, 131b, and 131c of the light source module 1A in this embodiment. As shown in Figure 12, by placing the anti-reflective device 320 near the monitor ports 131a, 131b, and 131c, leakage of monitor light can be prevented when using the display light. This suppresses visual flicker caused by leakage of monitor light and prevents interference with the display light.

[0175] The anti-reflective device 320 has the function of attenuating or scattering unwanted monitor light emitted from the monitor ports 131a, 131b, and 131c. As the anti-reflective device 320, for example, a light attenuation device such as silicon material or an ND filter, or a light scattering device such as a diffuser plate or a textured material can be used.

[0176] The anti-reflective device 320 may be positioned so as to be in contact with the second end face 12, or it may be positioned at a certain distance away from the second end face 12.

[0177] The anti-reflective device 320 may be detachably mounted to the monitor ports 131a, 131b, and 131c. When monitor light is not required, the monitor ports 131a, 131b, and 131c are covered by the anti-reflective device 320. When monitor light is required, the anti-reflective device 320 is removed from the monitor ports 131a, 131b, and 131c.

[0178] <Optical System> The optical system 500 in this embodiment will now be described. Figure 13 is a conceptual diagram of the optical system 500 in this embodiment.

[0179] The optical system 500 constitutes an image display device that displays information that can be visually recognized as images (still images and moving images). The optical system 500 can be implemented in, for example, glasses-type terminals such as XR glasses 600.

[0180] The optical system 500 shown in Figure 13 includes a light source module 510, an optical system 520, a laser driver 530, an optical scanning mirror driver 540, and a video controller 550 that controls these drivers.

[0181] The optical system 500 can be equipped with the light source module 1A in this embodiment as the light source module 510. The light source module 510 is installed, for example, on the frame 601 of the XR glasses 600.

[0182] The optical system 520 optically processes the emitted light LE from the light source module 510. The emitted light LE is visible light (display light) emitted from the optical output port 191 of the light source module 1A in this embodiment.

[0183] The optical system 520 includes, for example, a collimator lens 521, a slit 522, an ND filter 523, and a light scanning mirror 524. The optical system 520 shown in Figure 13 is an example, and other configurations are possible. The light source module 510 and the light scanning mirror 524 constitute the optical engine of the present invention.

[0184] For example, a MEMS mirror can be used as the optical scanning mirror 524. To project a two-dimensional image, it is preferable to use a two-axis MEMS mirror as the optical scanning mirror 524, which vibrates to reflect laser light by changing angles in the horizontal and vertical directions.

[0185] In the XR glasses 600 shown in Figure 13, a light source module 510 attached to the frame 601 emits light LE. The emitted light LE is reflected by the optical scanning mirror 524 and then reflected again by the lens 602 of the XR glasses 600. The light reflected by the lens 602 enters the human eyeball and forms an image on the retina. This allows the image to be visually recognized.

[0186] [Derivative example of the first embodiment] Figure 14 is a schematic plan view of the light source module 1A in a derivative example of the first embodiment. Figure 15 is a schematic plan view showing the light source module 1A of Figure 14 with the electrodes 200 and pad portion 201 removed.

[0187] As shown in Figures 14 and 15, the optical output port 191 may be located on the second end face 12. The output optical waveguide 181 connected to the optical multiplexer 180 extends linearly in the X direction and is connected to the optical output port 191 provided on the second end face 12. By locating the optical output port 191 on the second end face 12, which is located on the opposite side of the optical incident surface (first end face 11), the flexibility of mounting the light source module 1A can be increased.

[0188] [Second Embodiment] A second embodiment of the present invention will now be described. Figure 16 is a schematic plan view of the light source module 1B in this embodiment. Figure 17 is a schematic plan view showing the light source module 1B of Figure 16 with the electrodes 200 and pad portion 201 removed. In the second embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and their descriptions are omitted as appropriate.

[0189] The light source module 1B in the second embodiment has an optical device 10B. The optical device 10B differs from the optical device 10A in the first embodiment in that the Mach-Zehnder type optical waveguides constituting the optical modulation sections 170a, 170b, and 170c are constructed using folded optical waveguides. Furthermore, the electrodes 200 of the optical device 10B have a shape that is compatible with the folded optical waveguides.

[0190] As shown in Figures 16 and 17, the branched waveguides 172a and 173a constituting the optical modulation section 170a have folded sections 176 and 177 that reverse the direction of optical propagation. The branched waveguides 172a and 173a are curved in a U-shape at the two folded sections 176 and 177. In the parts excluding the folded sections 176 and 177, the branched waveguides 172a and 173a are straight and extend parallel to the Y direction. Similarly, the branched waveguides 172b and 173b constituting the optical modulation section 170b, and the branched waveguides 172c and 173c constituting the optical modulation section 170c are also curved in a U-shape at the folded sections 176 and 177.

[0191] By employing folded optical waveguides in the optical modulation sections 170a, 170b, and 170c, the length of the optical device 10B in the optical incidence direction (length in the X direction) of the optical input ports 110a, 110b, and 110c can be shortened. As a result, the entire optical device 10B can be miniaturized.

[0192] Furthermore, the monitoring optical waveguides 130a, 130b, and 130c are connected to the monitoring ports 131a, 131b, and 131c located on the second end face 12, and extend in the direction of optical incidence (X direction) of the optical input ports 110a, 110b, and 110c. By shortening the length of the optical device 10B in the X direction, the monitoring optical waveguides 130a, 130b, and 130c can be shortened, thereby reducing the propagation loss of the monitoring light.

[0193] Furthermore, by employing folded optical waveguides, sufficient length can be secured for the branch waveguides 172a, 173a, 172b, 173b, 172c, and 173c to which the electric field is applied. As a result, the drive voltage required for modulation of the display light can be reduced, and the overall power consumption of the optical device 10B can be reduced.

[0194] [Derivative example of the second embodiment] Figure 18 is a schematic plan view of the light source module 1B in a derivative example of the second embodiment. Figure 19 is a schematic plan view showing the light source module 1B of Figure 18 with the electrodes 200 and pad portion 201 removed.

[0195] As shown in Figures 18 and 19, the optical output port 191 may be located on the second end face 12. The output optical waveguide 181 connected to the optical multiplexer 180 extends linearly in the X direction and is connected to the optical output port 191 located on the second end face 12. By locating the optical output port 191 on the second end face 12, which is located on the opposite side of the light incident surface (first end face 11), the flexibility of mounting the light source module 1B can be increased.

[0196] In the second embodiment, the light source module 1B is capable of performing active alignment, similar to the first embodiment. Similarly, it is also possible to include an anti-reflective device 320 and to integrate the light source module 1B into the optical system 500.

[0197] [Third Embodiment] A third embodiment of the present invention will now be described. Figure 20 is a schematic plan view of the light source module 1C in this embodiment. Figure 21 is a schematic plan view showing the light source module 1C of Figure 20 with the electrodes 200 and pad portion 201 removed. In the third embodiment, the same reference numerals are used for components that are the same as in the first and second embodiments, and their descriptions are omitted as appropriate.

[0198] The light source module 1C in the third embodiment has an optical device 10C. The optical device 10C differs from the optical device 10A in the first embodiment in that the modulation optical waveguides 151a, 151b, and 151c are bent substantially vertically at the bent portions 152a, 152b, and 152c.

[0199] As shown in Figures 20 and 21, the modulation optical waveguide 151a is bent approximately perpendicularly at the bent section 152a located between the higher-order mode filter 150a and the optical modulation section 170a. The branch waveguides 172a and 173a constituting the optical modulation section 170a extend in the Y direction. Similarly, the modulation optical waveguide 151b is bent approximately perpendicularly at the bent section 152b located between the higher-order mode filter 150b and the optical modulation section 170b. The branch waveguides 172b and 173b constituting the optical modulation section 170b extend in the Y direction. Similarly, the modulation optical waveguide 151c is bent approximately perpendicularly at the bent section 152c located between the higher-order mode filter 150c and the optical modulation section 170c. The branch waveguides 172c and 173c constituting the optical modulation section 170c extend in the Y direction.

[0200] The output optical waveguide 181 connected to the optical multiplexer 180 extends linearly in the Y direction and is connected to the optical output port 191 located on the fourth end face 14.

[0201] In this embodiment, by increasing the length of the optical device 10C in the Y direction, sufficient length can be ensured for the branch waveguides 172a, 173a, 172b, 173b, 172c, and 173c to modulate light. On the other hand, the length of the optical device 10C in the X direction can be shortened.

[0202] The monitoring optical waveguides 130a, 130b, and 130c are connected to the monitoring ports 131a, 131b, and 131c located on the second end face 12 and extend in the direction of optical incidence (X direction) of the optical input ports 110a, 110b, and 110c. By shortening the length of the optical device 10B in the X direction, the monitoring optical waveguides 130a, 130b, and 130c can be shortened, thereby reducing the propagation loss of the monitoring light.

[0203] In the third embodiment, the light source module 1C is capable of performing active alignment, similar to the first embodiment. Similarly, it is also possible to include an anti-reflective device 320 and to integrate the light source module 1C into the optical system 500.

[0204] [Fourth Embodiment] A fourth embodiment of the present invention will now be described. Figure 22 is a schematic plan view of the light source module 1D in this embodiment. Figure 23 is a schematic plan view showing the light source module 1D of Figure 22 with the electrodes 200 and pad portion 201 removed. In the fourth embodiment, the same reference numerals are used for components that are the same as in the third embodiment, and their descriptions are omitted as appropriate.

[0205] The light source module 1D in the fourth embodiment has an optical device 10D. The optical device 10D differs from the optical device 10C in the third embodiment in that the Mach-Zehnder type optical waveguides constituting the optical modulation sections 170a, 170b, and 170c are constructed using folded optical waveguides. In the optical device 10D, the modulation optical waveguides 140a, 140b, and 140c are bent approximately vertically at the bending sections 141a, 141b, and 141c, but they may also be bent at the modulation optical waveguides 151a, 151b, and 151c, similar to the optical device 10C. Furthermore, the electrodes 200 of the optical device 10D have a shape that is compatible with folded optical waveguides.

[0206] As shown in Figures 22 and 23, the branched waveguides 172a and 173a constituting the optical modulation section 170a have folded sections 176 and 177 that reverse the direction of optical propagation. The branched waveguides 172a and 173a are curved in a U-shape at the two folded sections 176 and 177. In the parts excluding the folded sections 176 and 177, the branched waveguides 172a and 173a are straight and extend parallel to the Y direction. Similarly, the branched waveguides 172b and 173b constituting the optical modulation section 170b, and the branched waveguides 172c and 173c constituting the optical modulation section 170c are also curved in a U-shape at the folded sections 176 and 177.

[0207] By employing folded optical waveguides in the optical modulation sections 170a, 170b, and 170c, the length of the optical device 10D in the optical incidence direction (length in the X direction) of the optical input ports 110a, 110b, and 110c can be shortened. As a result, the entire optical device 10D can be further miniaturized.

[0208] Furthermore, the monitoring optical waveguides 130a, 130b, and 130c are connected to the monitoring ports 131a, 131b, and 131c located on the second end face 12, and extend in the direction of optical incidence (X direction) of the optical input ports 110a, 110b, and 110c. By shortening the length of the optical device 10D in the X direction, the monitoring optical waveguides 130a, 130b, and 130c can be shortened, thereby reducing the propagation loss of the monitoring light.

[0209] Furthermore, by employing folded optical waveguides, sufficient length can be secured for the branch waveguides 172a, 173a, 172b, 173b, 172c, and 173c to which the electric field is applied. As a result, the drive voltage required for modulation of the display light can be reduced, and the overall power consumption of the optical device 10D can be reduced.

[0210] In the fourth embodiment, the light source module 1D is capable of active alignment, similar to the first embodiment. Similarly, it is also possible to include an anti-reflective device 320 and to integrate the light source module 1D into the optical system 500.

[0211] Although various embodiments of the present invention have been described, the present invention is not limited to these embodiments. Various modifications and changes are possible without departing from the spirit of the present invention, and the embodiments can be combined as appropriate.

[0212] As described above, the present invention has the effect of stably obtaining sufficient monitor light from the monitor port, and is useful in optical device technologies in general that utilize visible light, and especially in XR glasses that project image display light. [Explanation of Symbols]

[0213] 1A, 1B, 1C, 1D, 510 Light Source Modules 10A, 10B, 10C, 10D, Optical devices 11 First end surface 12 Second end face 13 Third end face 14 4th end face 101 circuit board 102 Optical functional layer 103 Optical waveguide layer 103a Slab layer 103b, 103b1, 103b2, 103b3 Ridge section 104 First Buffer Layer 105 Second Buffer Layer 106 Protective layer 106a End 110a, 110b, 110c optical input ports 111a, 111b, 111c input optical waveguide 120a, 120b, 120c, 171a, 171b, 171c Optical branching section 130a, 130b, 130c Optical waveguides for monitoring 131a, 131b, 131c Monitor Ports 135a, 135b, 135c, 161a, 161c, 162b, 162c, 163a, 163b, 163c, 164a, 164b, 164c Tapered section 135a1, 161c1, 162c2, 163c1, 164c2 narrow end 135a2, 161c2, 162c1, 163c2, 164c1 Wide end 135a3, 161c3, 163c3 Widening section 140a, 140b, 140c, 151a, 151b, 151c, 175a, 175b, 175c Optical waveguide for modulation 141a, 141b, 141c, 152a, 152b, 152c, 182 Bend section 150a, 150b, 150c higher-order mode filters 150a1 Curved waveguide 150a2, 150a3 curved section 160a, 160b, 160c Cross Waveguides 162c3, 164c3 Reduced width part 165a, 165b, 165c Cross intersection 166 Connection section 170a, 170b, 170c Optical Modulation Section 172a, 172b, 172c, 173a, 173b, 173c Branch Waveguides 174a, 174b, 174c, 180 Optical multiplexing section 176, 177 Folded section 181 Output optical waveguide 191 Optical output ports 200 electrodes 200G reference electrode 200S drive electrode 201 Pad section 201a Top side 301a, 301b, 301c Visible light laser light source 302a, 302b, 302c subcarriers 303a, 303b, 303c joints 310 Optical detection device 320 Anti-reflective devices 500 Optical Systems 520 Optical system 521 Collimator Lens 522 Slit 523 ND filter 524 Optical Scanning Mirror 530 Laser Driver 540 Optical Scanning Mirror Driver 550 Video Controller 600 XR Glasses 601 frame 602 Lens LE output light

Claims

1. An optical device comprising a substrate and an optical functional layer formed on the main surface of the substrate, The aforementioned optical functional layer is Each of the multiple visible light laser light sources has an optical input port into which the visible light emitted from each visible light laser light source can be input, An input optical waveguide connected to each optical input port, An optical branching unit having an input section connected to each optical input port and two output sections, A monitoring optical waveguide connected to one of the output sections of each optical branching section, A monitor port connected to each monitor's optical waveguide and emitting monitor light to the outside, A first optical waveguide connected to the other output section of each optical branching section, An optical modulation unit connected to each first optical waveguide, A second optical waveguide connected to each optical modulation section, An optical multiplexer connected to each second optical waveguide, The output optical waveguide connected to the optical multiplexer, An optical output port connected to the output optical waveguide and which emits the combined light from the optical multiplexer to the outside, An optical device characterized by comprising the following features.

2. The optical device according to claim 1, characterized in that the width of the monitoring optical waveguide is wider than the width of the optical waveguide constituting the optical modulation section.

3. The optical device according to claim 2, characterized by comprising a tapered portion that expands the width of the optical waveguide for monitoring.

4. The optical device according to claim 1, characterized in that it is provided with a crossing waveguide at the intersection of the monitoring optical waveguide and the first optical waveguide.

5. The optical device according to claim 4, characterized in that the crossing waveguide has a cross-shaped intersection located at the center of the intersection and a tapered portion that expands the width of the monitoring optical waveguide or the first optical waveguide toward the cross-shaped intersection.

6. The optical device according to claim 4, characterized in that a higher-order mode filter is provided between the cross waveguide and the optical modulation section to remove higher-order mode light.

7. The optical device according to claim 6, characterized in that the higher-order mode filter has a curved waveguide that curves with a predetermined curvature.

8. A protective layer is provided on the upper surface of the aforementioned optical functional layer, The optical device according to claim 1, characterized in that a portion of the pad portion electrically connected to the electrode of the optical modulation portion is exposed to the outside without being covered by the protective layer.

9. The optical device according to claim 1, characterized in that the optical waveguide constituting the optical modulation section has a folded portion that reverses the direction of optical propagation.

10. The optical device according to claim 1, characterized in that at least a portion of the optical waveguide constituting the optical modulation section is formed in a direction perpendicular to the optical incidence direction of the optical input port.

11. An optical device according to any one of claims 1 to 10, The plurality of visible light laser light sources, A light source module characterized by comprising the following features.

12. A method for manufacturing a light source module according to claim 11, The visible light emitted from the visible light laser light source is incident on the optical input port. The light emitted from the monitor port is directed into the optical detection device. Based on the detection results of the optical detection device, the relative position of the visible light laser light source with respect to the optical device is adjusted. A method for manufacturing a light source module, characterized by fixing the visible light laser light source to the optical device at a position where the optical axis of the visible light emitted from the visible light laser light source coincides with the center position of the optical input port.

13. The light source module according to claim 11, A light scanning mirror that reflects light emitted from the light source module at a different angle to display an image, An optical engine characterized by having the following features.

14. XR glasses characterized by being equipped with the optical engine described in claim 13.

Images