Electro-optical element, light source module, optical engine, and XR glasses

Abstract

Provided is an electro-optical element capable of forming a light source module in which the ratio of the intensity of output light to the intensity of light emitted from a light source to an optical waveguide is high. An electro-optical element (100) is provided with a substrate and an optical functional layer formed on the main surface of the substrate, and the optical functional layer has: a light incidence side optical waveguide (21) that guides light emitted from a light source; an optical branching unit (51) that branches the light incidence side optical waveguide (21) into two optical waveguides (21a, 21b) for light modulation; a Mach-Zehnder type light modulation unit (40) that modulates the light guided by the two light modulation optical waveguides (21a, 21b); an optical multiplexing / branching unit (52) for branching two optical modulation optical waveguides (21c, 21d), which guide the modulated light modulated by the Mach-Zehnder optical modulation unit (40), into one monitoring optical waveguide (3) and a plurality of optical output-side optical waveguides (21e, 21f); and an optical multiplexing unit (53) that causes the plurality of light output-side optical waveguides (21e, 21f) to become one light output optical waveguide (22).

Description

Technical Field

[0001] The invention relates to an electro-optical element, a light source module, an optical engine and XR glasses. Background Art

[0002] Currently, glasses-type terminals are being studied in technologies such as VR (Virtual Reality) and AR (Augmented Reality). In recent years, retinal scanning displays that enable users to recognize images by forming an image on the user's retina by two-dimensionally scanned light have attracted much attention as glasses-type terminals.

[0003] Generally, in a retinal scanning display, three colors of visible light emitted from a light source are combined on one optical axis. The combined three colors of visible light are transmitted to the image display unit. The image display unit performs a two-dimensional scan on the transmitted light and makes it incident on the user's pupil. The incident light forms an image on the user's retina, and the user recognizes the image. In this case, the retina is the screen that displays the image.

[0004] As XR glasses such as retinal scanning displays, there are XR glasses with a light source module, which has a light source and an electro-optical element that receives light emitted from the light source. As the light source, LEDs (Light Emitting Diodes) and LDs (Laser Diodes) that emit light of wavelengths corresponding to various colors of R (red), G (green), and B (blue) are used. As the electro-optical element, there is an element with an optical waveguide composed of lithium niobate (LiNbO3).

[0005] Patent document 1 describes an optical modulator having a substrate having an electro-optical effect, and the optical modulator includes a first optical waveguide for incident first light, a second optical waveguide for incident second light with a wavelength longer than that of the first light, and a third optical waveguide for incident third light with a wavelength longer than that of the second light.

[0006] Patent Document 2 describes an optical waveguide element, which includes: a substrate having an electro-optical effect; an optical waveguide formed on the substrate; and a light receiving element disposed on the substrate to monitor an optical wave propagating in the optical waveguide or an optical wave radiated from the optical waveguide. The optical waveguide element described in Patent Document 2 includes a monitoring optical waveguide extending from the optical waveguide to the light receiving element.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent No. 6728596

[0010] Patent Document 2: Japanese Patent Application Publication No. 2021-162642 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The amount of light emitted from a light source such as an LD (laser diode) varies according to temperature. Therefore, in a light source module having a light source such as an LD and an electro-optical element into which light emitted from the light source is incident, the intensity (amount of light) of the output light emitted from the electro-optical element varies according to temperature. In addition, when the electro-optical element of the light source module has an optical waveguide composed of lithium niobate (LiNbO3), the modulation waveform changes (DC drift) as the application time of a DC (direct current) voltage that changes the refractive index of the optical waveguide passes.

[0013] Therefore, in conventional light source modules, a multimode interferometer (MMI) is used to branch modulated light modulated by an electro-optical element into two types: monitor light and output light, and a photodetector is used to detect temperature-induced light intensity variation and / or DC drift of the monitor light.

[0014] Then, based on the detection result of the monitor light, the control unit controls the current supplied to the light source or controls the DC (direct current) voltage that changes the refractive index of the optical waveguide, thereby performing feedback control to control the variation of the modulated light emitted from the electro-optical element.

[0015] Therefore, in the existing light source module, in order to perform feedback control, the light of 1 / 2 intensity of the modulated light emitted from the electro-optical element is used as the monitoring light. Therefore, in the existing light source module, it is required that the ratio of the output light relative to the light incident from the light source to the light waveguide is low, and the ratio of the output light is increased.

[0016] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electro-optical element capable of forming a light source module having a high ratio of the intensity of output light to the intensity of light incident from a light source to a light waveguide.

[0017] Another object of the present invention is to provide a light source module including the electro-optical element of the present invention and having a high ratio of the intensity of output light to the intensity of light incident from a light source to a light waveguide.

[0018] Another object of the present invention is to provide an optical engine and XR glasses equipped with a light source module having a high ratio of the intensity of output light to the intensity of light incident from the light source to the optical waveguide.

[0019] Technical solutions to solve problems

[0020] One aspect of the present invention provides an electro-optical element, which includes a substrate and an optical functional layer formed on a main surface of the substrate, wherein the optical functional layer has: a light incident side optical waveguide that guides light emitted from a light source; an optical branching portion that branches the light incident side optical waveguide into two optical waveguides for light modulation; a Mach-Zehnder type optical modulation portion that modulates the light guided in the two optical waveguides for light modulation; an optical combining branching portion that branches the two optical waveguides for light modulation into one monitoring optical waveguide and a plurality of optical output side optical waveguides, the two optical waveguides for light modulation guiding modulated light modulated by the Mach-Zehnder type optical modulation portion; and an optical combining portion that converts the plurality of optical output side optical waveguides into one optical output waveguide.

[0021] Effects of the Invention

[0022] The electro-optical element of the present invention has an optical functional layer, which has: an optical wave combining and branching section that branches two optical waveguides for light modulation into one optical waveguide for monitoring and a plurality of optical waveguides on the light output side, the two optical waveguides for light modulation guiding the modulated light modulated by the Mach-Zehnder type optical modulation section; and an optical wave combining section that makes the plurality of optical waveguides on the light output side become one optical waveguide for light output. Therefore, in the electro-optical element of the present invention, only 1 / (the number of optical waveguides on the light output side + 1) of the modulated light emitted from the electro-optical element is used as monitoring light. Therefore, in the light source module having the electro-optical element of the present invention and a light source, the amount of light used as monitoring light is small, and the ratio of the intensity of the output light to the intensity of the light incident from the light source to the optical waveguide is high.

[0023] The light source module of the present invention comprises the electro-optical element and the light source of the present invention. In addition, the optical engine and the XR glasses of the present invention are equipped with the light source module of the present invention. Therefore, the light source module, the optical engine and the XR glasses of the present invention can efficiently utilize the light emitted from the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic plan view showing the electro-optical element according to the first embodiment.

[0025] Figure 2 Cut off with X-X' Figure 1 A schematic cross-sectional view of the electro-optical element shown.

[0026] Figure 3 It is a schematic plan view showing an electro-optical element according to a second embodiment.

[0027] Figure 4 It is a schematic plan view showing an electro-optical element according to a third embodiment.

[0028] Figure 5 It is used for Figure 1The schematic plan view for explaining the light source module according to the fourth embodiment of the electro-optical element 100 according to the first embodiment is shown.

[0029] Figure 6 It is used for Figure 3 The schematic plan view for explaining the light source module according to the fifth embodiment of the electro-optical element 200 according to the second embodiment is shown.

[0030] Figure 7 It is used for Figure 4 The schematic plan view for explaining the light source module according to the sixth embodiment of the electro-optical element 300 according to the third embodiment is shown.

[0031] Figure 8 This is a conceptual diagram for explaining an example of the XR glasses of the present invention.

[0032] Fig. 9 It means in Figure 8 A conceptual diagram of a situation in which an image is projected directly onto the retina using light emitted from a light source module in XR glasses.

[0033] Fig. 10A 1 is a plan view of the optical multiplexing and branching section 52 and the optical waveguide connected thereto, in which a simulation of Experimental Example 1 was performed.

[0034] Fig. 10B yes Fig. 10A Cross-sectional view of line A-A'.

[0035] Fig. 10C yes Fig. 10A Cross-sectional view of line BB'. DETAILED DESCRIPTION

[0036] In order to solve the above-mentioned problems and provide an electro-optical element of a light source module capable of forming an output light intensity with a high ratio to the intensity of light incident from the light source to the light waveguide, the inventors of the present invention have repeatedly conducted in-depth research on an optical waveguide branching section that branches an optical modulation optical waveguide for guiding modulated light modulated by a Mach-Zehnder type optical modulation section into an optical waveguide for monitoring.

[0037] As a result, it was found that in the optical wave combining and branching section of the electro-optical element, the two optical modulation waveguides for guiding the modulated light modulated by the Mach-Zehnder optical modulation section are branched into three or more optical waveguides and only one monitoring optical waveguide is set, and the others are set as optical output side optical waveguides, which led to the present invention.

[0038] In the electro-optical element having such an optical multiplexing and branching section, only 1 / (the number of optical waveguides on the optical output side+1) of the modulated light emitted from the electro-optical element is used as monitoring light. Therefore, the amount of light used as monitoring light is small, the ratio of the intensity of the output light to the intensity of the light incident from the light source to the optical waveguide is high, and the light emitted from the light source can be efficiently used.

[0039] The present invention includes the following aspects.

[0040] [1] An electro-optical element comprising:

[0041] substrate; and

[0042] A light functional layer formed on the main surface of the substrate,

[0043] The optical functional layer has:

[0044] A light incident side optical waveguide that guides light emitted from the light source;

[0045] an optical branching section that branches the light incident side optical waveguide into two optical waveguides for light modulation;

[0046] A Mach-Zehnder type optical modulation unit that modulates light guided through two optical waveguides for light modulation;

[0047] an optical wave combining and branching unit that branches two optical waveguides for light modulation into one optical waveguide for monitoring and a plurality of optical waveguides for light output, wherein the two optical waveguides for light modulation guide modulated light modulated by the Mach-Zehnder optical modulation unit; and

[0048] The optical combining section combines the plurality of light output side optical waveguides into one light output optical waveguide.

[0049] [2] The electro-optical element according to [1], wherein

[0050] The light incident side optical waveguide, the light modulation optical waveguide, the monitoring optical waveguide, the light output side optical waveguide, and the light output optical waveguide are all made of lithium niobate.

[0051] [3] The electro-optical element according to [1], wherein

[0052] The optical branching unit, the optical combining branching unit, and the optical combining unit are all multi-mode interferometers.

[0053] [4] The electro-optical element according to [1], wherein

[0054] The number of the plurality of light output side optical waveguides is two.

[0055] [5] The electro-optical element according to [1], comprising:

[0056] a photodetector for detecting a change in the amount of the monitoring light guided through the monitoring optical waveguide;

[0057] A control unit corrects the intensity of the light guided through the light modulation optical waveguide in accordance with a detection result of the monitor light by the photodetector.

[0058] [6] The electro-optical element according to [1], wherein

[0059] The optical function layer further includes a light input port for inputting light emitted from the light source to the light incident side optical waveguide, and the light incident side optical waveguide guides the light input from the light input port.

[0060] [7] The electro-optical element according to [5], wherein

[0061] The optical functional layer further comprises: bias electrodes, which are respectively provided on the two optical waveguides for light modulation, the two optical waveguides for light modulation being arranged between the optical branching section and the Mach-Zehnder optical modulation section,

[0062] The DC voltage applied from the bias electrode to the light modulation optical waveguide is controlled by the control unit.

[0063] [8] The electro-optical element according to [1], wherein

[0064] The optical functional layer has three optical modulation parts.

[0065] The optical modulation unit includes the light incident side optical waveguide, the optical branching unit, the Mach-Zehnder optical modulation unit, the optical multiplexing branching unit, and the optical multiplexing unit.

[0066] The light incident side optical waveguide of each optical modulator guides lights of different wavelengths.

[0067] [9] A light source module comprising:

[0068] light source; and

[0069] The electro-optical element according to any one of [1] to [8].

[0070]

[10] A light source module comprising

[0071] light source; and

[0072] [5] The electro-optical element,

[0073] The current supplied to the light source is controlled by the control unit.

[0074]

[11] An optical engine equipped with the light source module described in [9].

[0075]

[12] A pair of XR glasses equipped with the light source module described in [9].

[0076] Hereinafter, the electro-optical element, light source module, optical engine and XR glasses of the present embodiment will be described in detail with reference to the drawings as appropriate. In the drawings used in the following description, in order to make the features of the present invention easy to understand, the features are sometimes partially enlarged for convenience. Therefore, the dimensional ratios of the various components are sometimes different from the actual ones. The materials, dimensions, etc. illustrated in the following description are only examples, and the present invention is not limited thereto, and can be appropriately changed and implemented within the scope of achieving the effects of the present invention.

[0077] 〔Electro-optical elements〕

[0078] [First embodiment]

[0079] Figure 1 It is a schematic plan view showing the electro-optical element according to the first embodiment. Figure 2 Cut off with X-X' Figure 1 A schematic cross-sectional view of the electro-optical element shown.

[0080] like Figure 2 As shown, Figure 1 The electro-optical element 100 shown in FIG. 1 includes a substrate 10 and an optical functional layer 20 formed on a main surface 10a of the substrate 10. Figure 2 As shown, the optical function layer 20 is composed of an optical waveguide core film 24 and an optical waveguide cladding (buffer) film 25 formed on the optical waveguide core film 24 so as to cover the optical waveguide core film 24 .

[0081] like Figure 1 As shown, the optical functional layer 20 has an optical input port 2a, an optical waveguide 21 on the light incident side, an optical branching portion 51, optical waveguides 21a, 21b, 21c, 21d for optical modulation, a Mach-Zehnder type optical modulation portion 40, an optical combining and branching portion 52, a monitoring optical waveguide 3, a monitoring light output port 2c, optical waveguides 21e, 21f on the light output side, an optical combining portion 53, an optical waveguide 22 for light output, and a light output port 2b.

[0082] The electro-optical element 100 of this embodiment has a substantially rectangular shape when viewed from above. Figure 1As shown, the electro-optical element 100 has four sides, namely, a first side surface 100A and a third side surface 100C along the short sides of the rectangle, and a second side surface 100B and a fourth side surface 100D along the long sides. In the electro-optical element 100 of this embodiment, the light input port 2a is provided on the first side surface 100A, and the light output port 2b is provided on the third side surface 100C. In addition, in the electro-optical element 100 of this embodiment, the monitoring light output port 2c is provided on the second side surface 100B.

[0083] In the electro-optical element 100 of the present embodiment, the positions where the light input port 2a, the light output port 2b, and the monitor light output port 2c are provided are not limited to Figure 1 For example, in the present embodiment, the monitoring light output port 2c is provided on the second side surface 100B as an example, but the monitoring light output port 2c may be provided on any of the first side surface 100A, the third side surface 100C, and the fourth side surface 100D without any particular limitation. In addition, when the monitoring light output port 2c is provided on the fourth side surface 100D, the monitoring light waveguide 3 may intersect with other light waveguides such as the light output side light waveguides 21e and 21f in a plan view, for example.

[0084] In addition, the optical input port 2a, the optical output port 2b, and the monitoring optical output port 2c may also use structures such as grating couplers or reflectors to input and output to the upper surface of the electro-optical element 100. In this case, the optical input port 2a, the optical output port 2b, and the monitoring optical output port 2c do not need to be provided on the first side surface 100A, the third side surface 100C, and the fourth side surface 100D, but may be provided anywhere on the upper surface of the electro-optical element 100.

[0085] In addition, in this embodiment, as the electro-optical element 100, an element having a substantially rectangular shape when viewed from above is taken as an example for explanation, but the planar shape of the electro-optical element 100 is not limited to a substantially rectangular shape, and can be appropriately determined according to the purpose of the electro-optical element 100, etc., and can also be any planar shape.

[0086] The light input port 2 a inputs light emitted from the light source into the light incident side optical waveguide 21 , and is provided on the first side surface 100A.

[0087] The light incident side optical waveguide 21 guides light emitted from the light source and input from the light input port 2 a .

[0088] The optical branching unit 51 branches one light incident side optical waveguide 21 into two optical modulation optical waveguides 21a and 21b. As the optical branching unit 51, a known device can be used, and a multi-mode interferometer (MMI) is preferable.

[0089] The Mach-Zehnder optical modulation unit 40 modulates the light guided through the two optical waveguides 21a and 21b for light modulation. As the Mach-Zehnder optical modulation unit 40, a known structure can be used. Figure 1 As shown in the figure, the Mach-Zehnder optical modulator 40 is provided with electrodes 26 and 27 for applying a modulation voltage to the Mach-Zehnder optical modulator 40. One end of the electrode 26 is connected to a power source (not shown), and the other end is connected to a terminal resistor 28. In addition, one end of the electrode 27 is connected to a power source (not shown), and the other end is connected to the terminal resistor 28. As the electrodes 26 and 27, for example, an electrode composed of an Au film, an electrode composed of a stacked film of a Ti film and an Au film, etc. can be used.

[0090] The optical multiplexing and branching section 52 couples two optical modulation optical waveguides 21c and 21d for guiding modulated light modulated by the Mach-Zehnder optical modulation section 40, and branches into one monitoring optical waveguide 3 and a plurality of optical output side optical waveguides 21e and 21f. If there are two optical output side optical waveguides 21e and 21f, the length of the optical multiplexing section 53 can be shortened, which is preferred.

[0091] In this embodiment, the case where there are two light output side optical waveguides 21e and 21f is described as an example, but the number of light output side optical waveguides may be multiple, and may be 3 or more. When there are 3 or more light output side optical waveguides, the amount of light used as monitor light in the modulated light emitted from the electro-optical element 100 can be further reduced.

[0092] As the optical multiplexing and branching unit 52 , a known device can be used, and a multi-mode interferometer (MMI) is preferable.

[0093] The optical combiner 53 couples a plurality of (two in this embodiment) optical output side waveguides 21e and 21f to form a single optical output waveguide 22. As the optical combiner 53, a known device can be used, and a multi-mode interferometer (MMI) is preferred.

[0094] In the present embodiment, it is preferred that at least one of the optical branching section 51, the optical multiplexing branching section 52, and the optical multiplexing section 53 is a multimode interferometer, and more preferably all of them are multimode interferometers. The multimode interferometer (MMI) can prevent the increase of the coupling length, for example, compared with the case where a directional coupler is provided instead of a multimode interferometer. Therefore, in the case where at least one of the optical branching section 51, the optical multiplexing branching section 52, and the optical multiplexing section 53 is a multimode interferometer, it is possible to take into account both the improvement of the degree of freedom and the miniaturization in the design of the electro-optical element 100. In addition, by selecting at least one of the optical branching section 51, the optical multiplexing branching section 52, and the optical multiplexing section 53 as a multimode interferometer, the loss of light caused by the manufacturing deviation of the electro-optical element 100 is reduced.

[0095] The electro-optical element 100 of the present embodiment preferably has a photodetector (not shown) for detecting changes in the amount of light of the monitoring light guided in the monitoring optical waveguide 3, and a control unit (not shown) for correcting the intensity of the light guided in the optical waveguides 21a, 21b, 21c, and 21d for optical modulation in accordance with the detection result of the monitoring light using the photodetector.

[0096] As the photodetector, for example, a well-known photodiode or the like can be used.

[0097] The control unit corrects the intensity of the light guided in the optical waveguides 21a, 21b, 21c, and 21d for light modulation in accordance with the detection result of the monitoring light using the light detector. For example, the control unit may control the current supplied to the light source (not shown) and / or the DC (direct current) voltage supplied to the electrodes 26 and 27 for applying the modulation voltage to the Mach-Zehnder type optical modulation unit 40 based on the detection result of the monitoring light.

[0098] In this embodiment, Figure 1 The light incident side optical waveguide 21, the light modulation optical waveguides 21a, 21b, 21c, 21d, the monitoring optical waveguide 3, the light output side optical waveguides 21e, 21f, and the light output optical waveguide 22 are all made of Figure 2 The optical waveguides are preferably formed of the optical waveguide core film 24 shown in FIG. Each of these optical waveguides has a ridge-like (convex) shape protruding from the first surface 24a of the optical waveguide core film 24 (see FIG. Figure 2 The cross-sectional shapes of the monitoring optical waveguide 3 and the optical output side optical waveguides 21e and 21f are shown in FIG. Figure 2 As shown, the first surface 24 a of the optical waveguide core film 24 is the upper surface of the portion (flat plate portion) other than the ridge shape of the optical waveguide core film 24 .

[0099] Figure 1 The cross-sectional shape of the light incident side optical waveguide 21, the optical modulation optical waveguides 21a, 21b, 21c, 21d, the monitoring optical waveguide 3, the light output side optical waveguides 21e, 21f, and the light output optical waveguide 22 shown can be any shape capable of guiding light, preferably a ridge-shaped shape, and can be set to, for example, a roughly rectangular, roughly trapezoidal, roughly triangular, roughly semicircular, or the like.

[0100] In the case where the cross-sectional shape of the optical waveguides (the light incident side optical waveguide 21, the light modulation optical waveguides 21a, 21b, 21c, 21d, the monitoring optical waveguide 3, the light output side optical waveguides 21e, 21f, the light output optical waveguide 22) of the electro-optical element 100 of the present embodiment is a ridge-shaped shape, the width ( Figure 2 The Wa in the figure can be set to be, for example, 0.2 μm or more and 5.0 μm or less, and the height ( Figure 2 The protrusion height (H) from the first surface 24a in the embodiment can be set to, for example, 0.1 μm or more and 1.0 μm or less.

[0101] The film thickness of the optical waveguide core film 24 of the electro-optical element 100 of the present embodiment can be set to, for example, 0.5 μm or more and 2 μm or less. The film thickness of the optical waveguide core film 24 refers to the film thickness of the portion (flat plate portion) of the optical waveguide core film 24 that is not in a ridge shape. The film thickness of the optical waveguide core film 24 can be appropriately determined according to the wavelength of light guided in the optical waveguide, the cross-sectional shape of the optical waveguide of the electro-optical element 100, and the like.

[0102] exist Figure 1 In the electro-optical element 100 shown, as Figure 2 The substrate 10 shown can use a known substrate, and can be appropriately determined according to the material of the optical functional layer 20. When the optical waveguide core film 24 of the optical functional layer 20 formed in contact with the main surface 10a of the substrate 10 and forming the optical waveguide is an epitaxial film composed of a lithium niobate (LiNbO3) film, a known single crystal substrate capable of growing an epitaxial film composed of a lithium niobate (LiNbO3) film is used as the substrate 10. In this case, the substrate 10 preferably has a lower refractive index than lithium niobate, and for example, a sapphire single crystal substrate, a silicon single crystal substrate, etc. can be used.

[0103] In the electro-optical element 100 of the present embodiment, a sapphire single crystal substrate is particularly preferably used as the substrate 10. The sapphire single crystal substrate has a lower refractive index than a lithium niobate (LiNbO3) film. Therefore, in the case where the optical waveguide core film 24 is an epitaxial film composed of a lithium niobate film, the substrate 10 can function as a cladding in the optical waveguide composed of the optical waveguide core film 24. Therefore, in the case where the substrate 10 is a sapphire single crystal substrate and the optical waveguide core film 24 is an epitaxial film composed of a lithium niobate film, a cladding is not separately provided between the substrate 10 and the optical waveguide core film 24, and the optical waveguide core film 24 can be suitably used as an optical waveguide.

[0104] The epitaxial film composed of lithium niobate (LiNbO3) film is easily formed into a c-axis oriented epitaxial film with respect to a single crystal substrate of various crystal orientations. Therefore, in the electro-optical element 100 of the present embodiment, when the optical waveguide core film 24 is composed of a c-axis oriented epitaxial film, i.e., a lithium niobate film, the crystal orientation of the substrate 10 is not particularly limited.

[0105] In addition, when the optical waveguide core film 24 is composed of a c-axis oriented epitaxial film, that is, a lithium niobate film, it has a three-dimensional symmetry. Therefore, it is desirable that the crystal orientation of the main surface 10a of the substrate 10 has the same symmetry as the optical waveguide core film 24. Therefore, when a sapphire single crystal substrate is used as the substrate 10, the main surface 10a is preferably a c-plane. In addition, when a silicon single crystal substrate is used as the substrate 10, the main surface 10a is preferably a (111) plane.

[0106] As the optical waveguide core film 24, a known optical waveguide core film can be used. As the optical waveguide core film 24, a c-axis oriented epitaxial film, i.e., a lithium niobate film is preferably used. The lithium niobate film forming the optical waveguide core film 24 has lithium niobate (LiNbO3) as a main component. Since lithium niobate has a large electro-optical constant, it is suitable as a material for an optical waveguide.

[0107] The composition of the lithium niobate film forming the optical waveguide core film 24 is, for example, a general formula of Li x Nb y O z (A in the formula is an element other than Li, Nb and O. x is 0.5 to 1.2, y is 0 to 0.5, and z is 1.5 to 4.)

[0108] A in the formula represents an element other than Li, Nb, and O. Examples of the element represented by A include K, Na, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Zn, Sc, and Ce. The element represented by A may be only one or two or more.

[0109] In the formula, x is 0.5 to 1.2, preferably 0.9 to 1.05.

[0110] In the formula, y is 0 to 0.5.

[0111] In the formula, z is 1.5 to 4, preferably 2.5 to 3.5.

[0112] When the optical waveguide core film 24 is composed of a c-axis oriented epitaxial film, i.e., a lithium niobate film, and the substrate 10 is composed of a single crystal substrate, the crystal orientation of the lithium niobate film on which the optical waveguide core film 24 is formed is aligned with respect to the crystal orientation of the substrate 10 as a base. More specifically, when the film surface of the lithium niobate film on which the optical waveguide core film 24 is formed is set as an XY plane and the film thickness direction is set as a Z axis, the crystals of the single crystal substrate on which the substrate 10 is formed and the crystals of the epitaxial film on which the optical waveguide core film 24 is formed are aligned in the X-axis, Y-axis, and Z-axis directions.

[0113] That the optical waveguide core film 24 is a c-axis oriented epitaxial film can be confirmed by, for example, the following two points: first, confirmation of the peak intensity of the orientation position by 2θ-θ X-ray diffraction; and second, confirmation of the pole by pole measurement.

[0114] Specifically, in order to prove that the optical waveguide core film 24 is a c-axis oriented epitaxial film, as a first condition, when performing measurement based on 2θ-θ X-ray diffraction, all peak intensities other than the target plane need to be less than 10% of the maximum peak intensity of the target plane, preferably less than 5%. In the c-axis oriented epitaxial film formed with the optical waveguide core film 24, the peak intensity other than the (00L) plane is less than 10% of the maximum peak intensity of the (00L) plane, preferably less than 5%. (00L) is a general term for equivalent planes such as (001) or (002).

[0115] In the above-mentioned conditions for confirming the peak intensity of the orientation position based on 2θ-θ X-ray diffraction, only the orientation in one direction is indicated. Therefore, even if the above-mentioned first condition is met, when the crystal orientation in the plane is not uniform, the intensity of the X-ray at a specific angle position will not increase, and no pole can be seen.

[0116] Therefore, in order to prove that the optical waveguide core film 24 is an epitaxial film with c-axis orientation, it is necessary to observe a pole in the pole measurement as the second condition.

[0117] Since LiNbO3 has a trigonal crystal structure, the number of poles of LiNbO3(014) in a single crystal becomes three. When a lithium niobate film is epitaxially grown, it is known that epitaxial growth is performed in a state of so-called twin crystals in which the crystals are symmetrically coupled by 180° rotated around the c-axis. In this case, since the three poles are symmetrically coupled in two lines, the number of poles becomes six.

[0118] In the electro-optical element 100 of the present embodiment, when a sapphire single crystal substrate whose main surface 10a is the c-plane is used as the substrate 10, for example, the c-axis of the lithium niobate film on which the optical waveguide core film 24 is formed is preferably offset by 5° or less, and more preferably coincident (0°) with the c-axis of the substrate 10. If the offset of the c-axis of the optical waveguide core film 24 and the substrate 10 is 5° or less, there will be no practical problems caused by the offset of the c-axis of the optical waveguide core film 24 and the substrate 10 in the characteristics of the electro-optical element 100.

[0119] In the electro-optical element 100 of the present embodiment, a known optical waveguide cladding (buffer) film 25 can be used as the optical waveguide cladding (buffer) film 25 formed on the optical waveguide core film 24. As the cladding (buffer) film 25, for example, a SiO2 film or the like can be used.

[0120] The electro-optical element 100 of the present embodiment includes an optical functional layer 20, the optical functional layer 20 having an optical multiplexing branching section 52 that branches two optical waveguides 21c and 21d for light modulation that guide modulated light modulated by a Mach-Zehnder type optical modulation section 40 into one optical waveguide 3 for monitoring and two optical waveguides 21e and 21f on the light output side, and an optical multiplexing section 53 that converts the two optical waveguides 21e and 21f on the light output side into one optical waveguide 22 for light output. Therefore, in the electro-optical element 100 of the present embodiment, only 1 / (the number of optical waveguides 21e and 21f on the light output side (2) + 1) of the modulated light emitted from the electro-optical element 100 is used as monitor light. Thus, the electro-optical element 100 of the present embodiment can form a light source module in which the amount of light used as monitor light in the modulated light emitted from the electro-optical element 100 is small, and the ratio of the intensity of the output light to the intensity of the light incident from the light source to the optical waveguide is high.

[0121] Furthermore, the electro-optical element 100 of the present embodiment includes a photodetector (not shown) for detecting a change in the light amount of the monitoring light guided in the monitoring optical waveguide 3, and a control unit (not shown) for correcting the intensity of the light guided in the optical waveguides 21a, 21b, 21c, and 21d for light modulation in accordance with the detection result of the monitoring light by the photodetector. In the electro-optical element 100 of the present embodiment, the control unit can perform feedback control such as controlling the current supplied to the light source (not shown) and / or controlling the DC (direct current) voltage supplied to the electrodes 26 and 27 for applying the modulation voltage to the Mach-Zehnder type optical modulation unit 40, based on the detection result of the monitoring light by the photodetector. Therefore, according to the electro-optical element 100 of the present embodiment, it is possible to emit stable modulated light in which the change due to temperature and / or DC drift is suppressed.

[0122] [Second embodiment]

[0123] Figure 3 FIG. 2 is a schematic plan view showing an electro-optical element according to a second embodiment. Figure 3 In the electro-optical element 200 of the second embodiment shown in FIG. Figure 1 and Figure 2 The same reference numerals are used for the components common to the electro-optical element 100 of the first embodiment, and description thereof may be omitted.

[0124] Figure 3 The electro-optical element 200 of the second embodiment shown in FIG. Figure 1 and Figure 2The electro-optical element 100 of the first embodiment shown is different in that two optical waveguides 21a and 21b for light modulation disposed between the light branching section 51 and the Mach-Zehnder optical modulation section 40 are provided with DC (direct current) bias electrodes 31 and 32, respectively, and the DC voltage applied to the optical waveguides 21a and 21b for light modulation from the bias electrodes 31 and 32 is controlled by the control section. As the bias electrodes 31 and 32, for example, bias electrodes composed of Au films, bias electrodes composed of a stacked film of Ti films and Au films, etc. can be used.

[0125] The control unit corrects the intensity of the light guided through the light modulation optical waveguides 21a, 21b, 21c, and 21d, and controls the DC voltage applied to the light modulation optical waveguides 21a and 21b from the bias electrodes 31 and 32, based on the detection result of the monitor light by the photodetector (not shown) that detects the light amount variation of the monitor light guided through the monitor optical waveguide 3. The control unit may control the current supplied to the light source (not shown), and / or the DC (direct current) voltage supplied to the electrodes 26 and 27 that apply the modulation voltage to the Mach-Zehnder type optical modulation unit 40, and control the DC voltage applied to the light modulation optical waveguides 21a and 21b from the DC (direct current) bias electrodes 31 and 32.

[0126] exist Figure 3 In the electro-optical element 200 of the second embodiment shown in FIG. Figure 1 and Figure 2 Similarly, the electro-optical element 100 of the first embodiment shown uses only 1 / (the number of light waveguides 21e and 21f on the light output side (2) + 1) of the modulated light emitted from the electro-optical element 200 as monitor light. Thus, the electro-optical element 200 of the second embodiment can also form a light source module in which the amount of light used as monitor light among the modulated light emitted from the electro-optical element 200 is small and the ratio of the intensity of the output light to the intensity of the light incident from the light source to the light waveguide is high.

[0127] in addition, Figure 3 The electro-optical element 200 of the second embodiment shown has a photodetector (not shown) for detecting changes in the amount of light of the monitoring light guided in the monitoring optical waveguide 3, and a control unit (not shown) for correcting the intensity of the light guided in the optical waveguides 21a, 21b, 21c, and 21d for optical modulation in accordance with the detection result of the monitoring light using the photodetector. DC (direct current) bias electrodes 31 and 32 are respectively provided on the two optical waveguides 21a and 21b for optical modulation arranged between the optical branching unit 51 and the Mach-Zehnder optical modulation unit 40.

[0128] Therefore, in Figure 3In the electro-optical element 200 shown, the control unit can perform feedback control of controlling the DC voltage applied to the light modulation optical waveguides 21a and 21b from the DC (direct current) bias electrodes 31 and 32 according to the detection result of the monitor light of the photodetector. Therefore, according to the electro-optical element 200 of this embodiment, by modulating the light guided in the light modulation optical waveguides 21a and 21b before reaching the Mach-Zehnder type light modulation unit 40, stable modulated light with suppressed fluctuations due to temperature and / or DC drift can be emitted.

[0129] Moreover, in Figure 3 In the electro-optical element 200 shown, feedback control can be performed by the control unit, and the feedback control controls the current supplied to the light source (not shown) and / or controls the DC (direct current) voltage supplied to the electrodes 26 and 27 for applying the modulation voltage to the Mach-Zehnder type light modulation unit 40, and controls the DC voltage applied to the light modulation optical waveguides 21a and 21b from the DC (direct current) bias electrodes 31 and 32. As a result, stable modulated light in which the variation due to temperature and / or DC drift is more effectively suppressed can be emitted from the electro-optical element 200 of this embodiment.

[0130] [Third Embodiment]

[0131] Figure 4 FIG. 1 is a schematic plan view showing an electro-optical element according to a third embodiment. Figure 4 In the electro-optical element 300 of the third embodiment shown in FIG. Figure 1 and Figure 2 The same reference numerals are used for the components common to the electro-optical element 100 of the first embodiment, and description thereof may be omitted.

[0132] Figure 3 The electro-optical element 300 of the third embodiment shown in FIG. Figure 1 and Figure 2 The electro-optical element 100 of the first embodiment shown is different in that the optical functional layer 20 has three light modulation units 20R, 20G, and 20B.

[0133] The electro-optical element 300 of the third embodiment has each optical modulator 20R, 20G, and 20B which respectively have an optical input port 2a, a light incident side optical waveguide 21, an optical branching portion 51, optical waveguides 21a, 21b, 21c, and 21d for optical modulation, a Mach-Zehnder type optical modulator 40, an optical combining and branching portion 52, a monitoring optical waveguide 3, a monitoring optical output port 2c, optical waveguides 21e and 21f on the light output side, an optical combining portion 53, an optical waveguide 22 for optical output, and an optical output port 2b.

[0134] The light incident side optical waveguides 21 of the light modulators 20R, 20G, and 20B guide lights of different wavelengths emitted from the light source and input from the light input port 2 a .

[0135] Specifically, the light-incident-side optical waveguide 21 of the optical modulator 20R guides red light having a peak wavelength of, for example, 610 nm to 750 nm. The light-incident-side optical waveguide 21 of the optical modulator 20G guides green light having a peak wavelength of, for example, 500 nm to 560 nm. The light-incident-side optical waveguide 21 of the optical modulator 20B guides blue light having a peak wavelength of, for example, 435 nm to 480 nm.

[0136] When the light incident side optical waveguides 21 of the light modulators 20R, 20G, 20B in the electro-optical element 300 of the third embodiment guide red light, green light, and blue light respectively, it can be preferably used for XR glasses capable of displaying full-color images, for example.

[0137] In each of the optical modulators 20R, 20G, and 20B of the electro-optical element 300 of the present embodiment, the positions of the optical input port 2a, the optical output port 2b, and the monitoring optical output port 2c are not limited to Figure 4 For example, in the present embodiment, the monitoring light output port 2c is provided on the second side surface 100B in all the light modulators 20R, 20G, and 20B, but the monitoring light output port 2c in each of the light modulators 20R, 20G, and 20B may be provided on any of the first side surface 100A, the third side surface 100C, and the fourth side surface 100D, respectively, without any particular limitation. For example, only the monitoring light output port 2c in the light modulator 20G, or only the monitoring light output port 2c in the light modulator 20B may be provided on the third side surface 100C or the fourth side surface 100D.

[0138] In addition, the optical input port 2a, the optical output port 2b, and the monitoring optical output port 2c may also use structures such as grating couplers or reflectors to input and output to the upper surface of the electro-optical element 300. In this case, the optical input port 2a, the optical output port 2b, and the monitoring optical output port 2c do not need to be provided on the first side surface 100A, the third side surface 100C, and the fourth side surface 100D, and may be provided anywhere on the upper surface of the electro-optical element 300.

[0139] In addition, the monitoring optical waveguide 3 in each optical modulation unit 20R, 20G, 20B of the electro-optical element 300 may intersect with the optical waveguides of other optical modulation units in a plan view (for example, see Figure 4 The monitoring optical waveguide 3 of the optical modulation units 20G and 20B).

[0140] In each of the optical modulators 20R, 20G, 20B of the electro-optical element 300 of this embodiment, electrodes 26, 27 for applying a modulation voltage to the Mach-Zehnder optical modulator 40 are connected to a power supply (not shown) at one end and to a terminal resistor (not shown) at the other end.

[0141] Figure 4 The light modulators 20R, 20G, and 20B in the electro-optical device 300 of the third embodiment are Figure 1 and Figure 2 As in the electro-optical element 100 of the first embodiment shown, only 1 / (the number of light waveguides 21e, 21f on the light output side (2) + 1) of the modulated light emitted from each optical modulator 20R, 20G, 20B is used as monitor light. Therefore, in the electro-optical element 300 of the third embodiment, the amount of light used as monitor light among the modulated light emitted from each optical modulator 20R, 20G, 20B is small, and the ratio of the intensity of the output light to the intensity of the light incident from the light source to the optical waveguide is high.

[0142] [Other examples]

[0143] The electro-optical element of the present invention is not limited to the electro-optical elements of the first to third embodiments described above, and can be implemented with appropriate changes within the scope of the gist thereof.

[0144] For example, Figure 4 The light modulators 20R, 20G, and 20B of the electro-optical element 300 of the third embodiment shown in FIG. Figure 3 The electro-optical element 200 of the second embodiment shown in the figure also has DC (direct current) bias electrodes 31 and 32 respectively arranged on two optical waveguides 21a and 21b for light modulation arranged between the optical branching section 51 and the Mach-Zehnder optical modulation section 40, and the DC voltage applied from the bias electrodes 31 and 32 to the optical waveguides 21a and 21b for light modulation is controlled by the control section.

[0145] 〔Light source module〕

[0146] [Fourth Embodiment]

[0147] Figure 5 It is used for Figure 1 The light source module 400 of the fourth embodiment is a schematic plan view for explaining the electro-optical element 100 of the first embodiment. The light source module 400 of the present embodiment includes the electro-optical element 100 of the first embodiment and a light source 30 .

[0148] like Figure 5As shown, the light source 30 emits light that is incident from the light input port 2a of the electro-optical element 100 and is guided in the light incident side optical waveguide 21. As the light source 30, a laser element such as a laser diode (LD) can be used, and various commercially available laser elements that emit light of a specific wavelength such as red light, green light, and blue light can be used.

[0149] Preferably, the light source module 400 of the present embodiment controls the current supplied to the light source 30 by the control unit of the electro-optical element 100 based on the detection result of the light amount variation of the monitoring light guided in the monitoring optical waveguide 3 of the electro-optical element 100. In this case, by controlling the current supplied to the light source 30, the light amount emitted from the light source 30 can be adjusted, and even if the modulated light varies due to temperature and / or DC drift, the intensity (light amount) of the light guided in the light modulation optical waveguides 21a, 21b, 21c, and 21d can be corrected according to the variation.

[0150] In addition, the light source module 400 of this embodiment includes the electro-optical element 100 and the light source 30 of the first embodiment, so the amount of light used as monitoring light is small, and the intensity of the output light is high relative to the intensity of the light incident from the light source 30 to the light incident side optical waveguide 21 via the light input port 2a.

[0151] [Fifth Embodiment]

[0152] Figure 6 It is used for Figure 3 The light source module 500 of the present embodiment includes the electro-optical element 200 of the second embodiment and a light source 30 .

[0153] Figure 6 The light source 30 shown is Figure 5 The electro-optical element 100 of the light source module 400 shown similarly emits light incident from the light input port 2a and guided through the light incident side optical waveguide 21. As the light source 30, a light source similar to the light source 30 of the light source module 400 can be used.

[0154] Preferably, the light source module 500 of the present embodiment controls the current supplied to the light source 30 by the control unit of the electro-optical element 200 based on the detection result of the light amount change of the monitoring light guided in the monitoring optical waveguide 3 of the electro-optical element 200. In this case, by controlling the current supplied to the light source 30, the light amount emitted from the light source 30 can be adjusted, and even if the modulated light changes due to temperature and / or DC drift, the intensity (light amount) of the light guided in the light modulation optical waveguides 21a, 21b, 21c, and 21d can be corrected according to the amount of change.

[0155] In addition, the light source module 500 of this embodiment has the electro-optical element 200 and the light source 30 of the second embodiment, so the amount of light used as monitoring light is small, and the intensity of the output light is high relative to the intensity of the light incident from the light source 30 to the light incident side optical waveguide 21 via the light input port 2a.

[0156] [Sixth Embodiment]

[0157] Figure 7 It is used for Figure 4 The light source module 600 of the sixth embodiment is a schematic plan view for explaining the electro-optical element 300 of the third embodiment. The light source module 600 of the present embodiment includes the electro-optical element 300 of the third embodiment and three light sources 30R, 30G, and 30B.

[0158] like Figure 7 As shown, the three light sources 30R, 30G, and 30B emit lights that are incident from the light input ports 2a of the light modulators 20R, 20G, and 20B of the electro-optical element 300 and guided through the light incident side optical waveguide 21 .

[0159] As the light sources 30R, 30G, and 30B, laser elements such as laser diodes (LD) can be used. As the light source 30R, for example, various commercially available laser elements that emit red light with a peak wavelength of 610 nm to 750 nm can be used. As the light source 30G, for example, various commercially available laser elements that emit green light with a peak wavelength of 500 nm to 560 nm can be used. As the light source 30B, for example, various commercially available laser elements that emit blue light with a peak wavelength of 435 nm to 480 nm can be used.

[0160] In the light source module 600 of the present embodiment, it is preferable that the current supplied to the three light sources 30R, 30G, and 30B is controlled by the control unit of the electro-optical element 300 according to the detection result of the light amount change of the monitoring light guided in the monitoring light waveguide 3 provided in each light modulation unit 20R, 20G, and 20B of the electro-optical element 300. In this case, by controlling the current supplied to the three light sources 30R, 30G, and 30B, the light amount emitted from the three light sources 30R, 30G, and 30B can be adjusted. Therefore, in each light modulation unit 20R, 20G, and 20B, even if the modulated light changes due to temperature and / or DC drift, the intensity of the light guided in the light modulation light waveguide 21a, 21b, 21c, and 21d can be corrected according to the change amount.

[0161] In addition, the light source module 600 of this embodiment has the electro-optical element 300 and light sources 30R, 30G, and 30B of the third embodiment. Therefore, the amount of light used as monitoring light is small, and the intensity of the output light is high relative to the intensity of the light incident from the light sources 30R, 30G, and 30B via the light input port 2a to the light incident side optical waveguide 21.

[0162] [Optical engine and XR glasses]

[0163] Figure 8 This is a conceptual diagram for explaining an example of the XR glasses of the present invention. Fig. 9 It means in Figure 8 A conceptual diagram of a situation in which an image is projected directly onto the retina using laser light emitted from a light source module in XR glasses.

[0164] The XR glasses (glasses) 1000 of this embodiment are glasses-type terminals. XR is a general term for virtual reality (VR: Virtual Reality), augmented reality (AR: Augmented Reality), and mixed reality (Mixed Reality). Fig. 9 The symbol L shown is image display light.

[0165] Figure 8 The XR glasses 1000 of the present embodiment shown are XR glasses in which the light source module 1001 of the above-mentioned embodiment is mounted on an optical engine 5001 provided on a frame 1010 .

[0166] like Figure 8 As shown, the optical engine 5001 includes a light source module 1001, a light scanning mirror 3001, an optical system 2001 connecting the light source module 1001 and the light scanning mirror 3001, a laser driver 1100, a light scanning mirror driver 1200, and a video controller 1300 for controlling these drivers.

[0167] For example, a MEMS mirror can be used as the light scanning mirror 3001. In order to project a 2D image, a biaxial MEMS mirror that vibrates to change the angle in the horizontal direction (X direction) and the vertical direction (Y direction) to reflect laser light is preferably used as the light scanning mirror 3001.

[0168] The optical system 2001 performs optical processing on the laser light emitted from the light source module 1001. As the optical system 2001, for example, an optical system including a collimator lens 2001a, a slit 2001b, and an ND filter 2001c can be used. Figure 8 The optical system 2001 shown is an example, and other structures are also possible.

[0169] exist Figure 8 In the XR glasses 1000 of the present embodiment shown in FIG. Fig. 9 As shown, the laser R irradiated from the light source module 1001 installed on the frame 1010 is reflected by the light scanning reflector 3001, and further reflected by the lens of the XR glasses 1000, enters the human eyeball E as image display light L, and can directly project an image (image) onto the retina M.

[0170] The XR glasses 1000 of this embodiment are equipped with the light source module 1001 of this embodiment, and therefore can efficiently utilize the light emitted from the light source.

[0171] The embodiments of the present invention are described in detail above with reference to the drawings, but the structures of the embodiments and their combinations are merely examples, and additions, omissions, substitutions, and other changes to the structures may be made without departing from the spirit of the present invention.

[0172] Example

[0173] Hereinafter, the present invention will be described in further detail using examples. However, the present invention is not limited to any of the examples shown below.

[0174] (Experimental Example 1)

[0175] Under the following conditions, Figure 1 to Figure 3 The optical multiplexing and branching section 52 included in the electro-optical device of the first to third embodiments shown was simulated. Fimmwave (Photon Design) was used as simulation software.

[0176] Fig. 10A 1 is a plan view of the optical multiplexing and branching section 52 and the optical waveguide connected thereto, in which a simulation of Experimental Example 1 was performed. Fig. 10B yes Fig. 10A Cross-sectional view of line A-A'. Fig. 10C yes Fig. 10A Cross-sectional view of line BB'.

[0177] exist Figure 10A to Figure 10C In, equivalent to Figure 1 to Figure 3 The components of the electro-optical element shown in FIG. Figure 1 to Figure 3 Same symbols.

[0178] In the simulation of Experimental Example 1, Figure 10A to Figure 10CThe light modulating optical waveguides 21c, 21d, the monitoring optical waveguide 3, and the light output side optical waveguides 21e, 21f shown all have the same cross-sectional shape. Specifically, they are composed of an optical waveguide core film 24 having a ridge-like shape, and are set to have a trapezoidal cross-sectional shape with a width of 2 μm at the upper base, a height of 0.7 μm, and an inclination angle of 80° on the side. In addition, the film thickness of the optical waveguide core film 24 (the film thickness of the portion that is not in the ridge-like shape (flat portion)) is set to 0.15 μm. In addition, the interval between the centers of the lower bases of the two optical waveguides 21c, 21d for light modulation, the interval between the centers of the lower bases of the two optical waveguides 21e, 21f on the light output side, and the interval between the centers of the lower bases of the monitoring optical waveguide 3 and the light output side optical waveguide 21e are all set to 4 μm.

[0179] The cross-sectional shape of the optical multiplexing and branching portion 52 is a trapezoidal cross-sectional shape with a height of 0.7 μm and a side surface inclination angle of 80°. Fig. 10A and Fig. 10C The lengths L_MMI and L_MMI_2 of the optical multiplexing and branching portion 52 shown in Table 1 are respectively set to the dimensions shown in Table 1, the width of the upper base of the region of length L_MMI is set to 8 μm, and the width of the upper base of the region of length L_MMI_2 is set to 12 μm.

[0180] Figure 10A to Figure 10C The substrate 10, the optical waveguide core film 24, and the optical waveguide cladding (buffer) film 25 shown are composed of the following materials.

[0181] [Material]

[0182] Substrate 10: Sapphire single crystal substrate

[0183] Optical waveguide core film 24; epitaxial film optical waveguide cladding (buffer) film 25 composed of lithium niobate (LiNbO3) film; SiO2 film

[0184] In the simulation of Experimental Example 1, as shown in Table 1, three types of input light, namely, red light 637nm, green light 520nm, and blue light 455nm, are used respectively, and the ratio of the output light intensity of the optical multiplexing and branching unit 52 to the input light intensity (output light intensity / input light intensity) and the ratio of the monitoring light intensity to the input light intensity (monitoring light intensity / input light intensity) are calculated.

[0185] The input light intensity is the Fig. 10A The output light intensity is the sum of the intensities of the light incident on the optical multiplexing and branching section 52 by the optical waveguides 21c and 21d for light modulation shown in FIG. Fig. 10A The sum of the intensities of the lights emitted from the optical multiplexing and branching section 52 to the light output side optical waveguides 21e and 21f is shown. Fig. 10AThe intensity of light emitted from the optical multiplexing and branching section 52 to the monitoring optical waveguide 3 is shown.

[0186] Table 1

[0187]

[0188] As shown in Table 1, no matter whether the input light is red light 637nm, green light 520nm, or blue light 455nm, it is possible to confirm that the ratio of the output light intensity of the optical multiplexing branching unit 52 to the input light intensity is as high as about 2 / 3, and the ratio of the monitoring light intensity to the input light intensity is as low as about 1 / 3 by using the optical multiplexing branching unit 52 that branches the two optical modulation optical waveguides 21c and 21d into one monitoring optical waveguide 3 and two optical output side optical waveguides 21e and 21f.

[0189] Description of Reference Numerals

[0190] 2a...Optical input port

[0191] 2b...Optical output port

[0192] 2c...Monitoring optical output port

[0193] 3... Optical waveguide for monitoring

[0194] 10…Substrate

[0195] 10a……Main surface

[0196] 20... Light functional layer

[0197] 20R, 20G, 20B... Optical modulation unit

[0198] 21... Light-incident-side optical waveguide

[0199] 21a, 21b, 21c, 21d... Optical waveguide for light modulation

[0200] 21e, 21f... optical waveguide on the light output side

[0201] 22... Optical waveguide for light output

[0202] 24... Optical waveguide core film

[0203] 25... Optical waveguide cladding (buffer) film

[0204] 26, 27...Electrodes

[0205] 28...Terminal resistance

[0206] 30, 30R, 30G, 30B... Light source

[0207] 31, 32...Bias electrode

[0208] 40...Mach-Zehnder optical modulation unit

[0209] 51...Optical branching unit

[0210] 52……Photosynthesis wave branching unit

[0211] 53……Photosynthesis

[0212] 100, 200, 300...Electro-optical components

[0213] 100A... First side

[0214] 100B... Second side

[0215] 100C…side 3

[0216] 100D...Fourth side

[0217] 400, 500, 600, 1001... Light source module

[0218] 1000...XR glasses (glasses)

[0219] 1010...frame

[0220] 1100...Laser Driver

[0221] 1200...Light scanning mirror driver

[0222] 1300... Video Controller

[0223] 2001...Optical Systems

[0224] 2001a……Collimating lens

[0225] 2001b... Slit

[0226] 2001c...ND filter

[0227] 3001...Light scanning mirror

[0228] 5001...Optical Engine

Claims

1. An electro-optical element, wherein: have: substrate; and a light functional layer formed on the main surface of the substrate, The optical functional layer has: A light incident side optical waveguide that guides light emitted from the light source; an optical branching section that branches the light incident side optical waveguide into two optical waveguides for light modulation; A Mach-Zehnder type optical modulation unit that modulates light guided through two optical waveguides for light modulation; an optical multiplexing and branching unit that branches two optical waveguides for light modulation into one optical waveguide for monitoring and a plurality of optical waveguides on the light output side, the two optical waveguides for light modulation guiding modulated light modulated by the Mach-Zehnder optical modulation unit; and The optical combining section combines the plurality of light output side optical waveguides into one light output optical waveguide.

2. The electro-optical element according to claim 1, wherein The light incident side optical waveguide, the light modulation optical waveguide, the monitoring optical waveguide, the light output side optical waveguide, and the light output optical waveguide are all made of lithium niobate. The optical branching unit, the optical combining branching unit, and the optical combining unit are all multi-mode interferometers.

3. The electro-optical element according to claim 1, wherein The number of the plurality of light output side optical waveguides is two.

4. The electro-optical element according to claim 1, wherein have: a photodetector for detecting a change in the amount of the monitor light guided through the monitor optical waveguide; as well as A control unit corrects the intensity of the light guided through the light modulation optical waveguide in accordance with a detection result of the monitor light by the photodetector.

5. The electro-optical element according to claim 1, wherein The optical function layer further has a light input port for inputting light emitted from the light source into the light incident side optical waveguide. The light-incident-side optical waveguide guides light input from the light input port.

6. The electro-optical element according to claim 4, wherein The optical functional layer further comprises: bias electrodes, which are respectively provided on the two optical waveguides for light modulation, the two optical waveguides for light modulation being arranged between the light branching section and the Mach-Zehnder type optical modulation section, The DC voltage applied from the bias electrode to the light modulation optical waveguide is controlled by the control unit.

7. The electro-optical element according to claim 1, wherein The optical functional layer has three optical modulation units, and the optical modulation units include the light incident side optical waveguide, the optical branching unit, the Mach-Zehnder optical modulation unit, the optical multiplexing branching unit, and the optical multiplexing unit. The light incident side optical waveguide of each optical modulation unit guides lights of different wavelengths.

8. A light source module, wherein: have: Light source; and The electro-optical element according to claim 4, The control unit controls the current supplied to the light source.

9. An optical engine, wherein: The light source module according to claim 8 is mounted thereon.

10. An XR glasses, wherein: The light source module according to claim 8 is mounted thereon.

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