Abstract: A core layer of an optical element includes a second conversion portion that converts a polarization mode of light from a TE1 mode to a TE0 mode. The second conversion portion includes: a splitting portion that splits the light in the TE1 mode incident from the first conversion portion into first split light in the TE0 mode and second split light in the TE0 mode which are in opposite phases; a coupling portion that couples the first split light that has propagated through a first branch waveguide and the second split light that has propagated through a second branch waveguide to emit the light in the TE0 mode; and a phase adjustment unit that adjusts a phase difference between the first split light and the second split light. The first branch waveguide and the second branch waveguide are arranged in a second direction.

Abstract: An optical element includes a mode converter that converts a polarization mode of visible light. The mode converter includes a conversion unit that converts a polarization mode of the visible light from a TM0 mode to a TE1 mode, and a splitting unit that splits the visible light in the TE1 mode into a first split light in the TE0 mode and a second split light in the TE0 mode, and adjusts a phase difference between the first split light and the second split light. The splitting unit includes a first branch wave guide through which the first split light propagates and a second branch wave guide through which the second split light propagates. An optical path length of the first split light in the first branch wave guide and an optical path length of the second split light in the second branch wave guide are different from each other.

Abstract: In a first region of a first conversion portion, a length of an upper tapered portion in a third direction continuously increases from a first length at a first end to a second length toward an intermediate position, and a length of a lower tapered portion in the third direction continuously increases from the first length at the first end to a third length, which is longer than the second length, toward the intermediate position. In a second region of the first conversion portion, a length of the upper tapered portion in the third direction continuously increases from the second length at the intermediate position to a fourth length, which is shorter than the third length, toward a second end, and a length of the lower tapered portion in the third direction continuously decreases from the third length at the intermediate position to the fourth length toward the second end.

Abstract: An optical circuit element capable of preventing stray light propagated through a part including a substrate of the optical circuit element from being emitted to the outside is provided. The optical circuit element has a substrate, an optical waveguide layer that is formed on one surface of the substrate, and a protective layer that is overlaid on the optical waveguide layer. The optical waveguide layer has an optical waveguide configured for light to be propagated therethrough. A groove portion, which reaches to a position deeper than the one surface from a surface of the protective layer toward the substrate, is formed. The optical circuit element further includes a light absorption layer that covers at least a bottom surface and a side surface of the groove portion.

Abstract: A method for projecting an image for a head-up display includes: emitting a light by a backlight; passing the light emitted by the backlight through a first light-transmissive member; passing the light transmitted through the first light-transmissive member through a light-diffusion structure; passing the light transmitted through the light-diffusion structure through a display screen; displaying an image on the display screen; and forming a virtual image corresponding to the image displayed on the display screen by reflecting the light transmitted through the display screen, in a target space.

Abstract: A transmission device of the present disclosure is a transmission device that transmits a visible light signal to a receiving device, and includes a laser light source configured to emit visible light, and an optical modulator configured to change intensity of the visible light and generate a visible light signal, in which the optical modulator has an optical waveguide that serves as a transmission path for the visible light, and the optical waveguide is formed of a material containing lithium niobate.

Abstract: An optical system includes a light guide member having an incident surface, a first surface and a light emergent surface; and at least one prism provided on the first surface and configured to reflect light received by the incident surface and travelling inside the light guide member, towards the light emergent surface. The light guide member provides an optical path along which the light that has entered through the incident surface is directly reflected from the prism and allowed to emerge from the light emergent surface. The light guide member also provides another optical path along which the light that has entered through the incident surface is once reflected from the second surface, reflected again from the prism, and then allowed to emerge from the light emergent surface. The optical system is configured to be coupled to a light source, to illuminate a display system which projects a virtual image onto a target space.

Abstract: An electro-optical element includes a substrate, and an optical functional layer formed on a main surface of the substrate, in which the optical functional layer includes an optical-input-side optical waveguide configured to guide light emitted from a light source, an optical branch part configured to branch the optical-input-side optical waveguide into two optical-modulation optical waveguides, a Mach-Zehnder optical modulation part configured to modulate light guided through the two optical-modulation optical waveguides, an optical coupling and branch part configured to branch the two optical-modulation optical waveguides configured to guide modulated light modulated by the Mach-Zehnder optical modulation part into one monitoring optical waveguide and a plurality of optical-output-side optical waveguides, and an optical coupling part configured to make the plurality of optical-output-side optical waveguides as one optical-output optical waveguide.

Abstract: A display device incudes: an image generating device that generates light that indicates an image (image light); a first light guide that includes a first output hologram element from which the image light exits; and a second light guide that includes a second output hologram element from which the image light exits. Each of the first light guide and the second light guide is in a curved shape. The image light emitted from the image generating device enters the first light guide. A portion of the 10 image light that has entered the first light guide enters the second light guide. A light quantity distribution of the image light exiting the first output hologram element is different from a light quantity distribution of the image light exiting the second output hologram element.

Abstract: A projection device includes: a plurality of light sources arranged in a first direction; a spatial modulation element that modulates incident light into image information and emits the image information; a lens that changes an optical path of light emitted from each of the plurality of light sources such that the light emitted from each light source reaches substantially the same region of an incident surface of the spatial modulation element; and a first reflective optical member that deflects the light emitted from the lens toward the spatial modulation element, the first reflective optical member having a shape that reflects light emitted from the lens so as to be incident on an arbitrary point on the incident surface of the spatial modulation element at a predetermined reference incident angle.

Abstract: A transmission device of the present disclosure is a transmission device that transmits a visible light signal to a receiving device, and includes a laser light source configured to emit visible light, and an optical modulator configured to change intensity of the visible light and generate a visible light signal, in which the optical modulator has an optical waveguide that serves as a transmission path for the visible light, and the optical waveguide is formed of a material containing lithium niobate.

Abstract: Provided is a head-up display including a backlight configured to emit light, a light-diffusion member through which the light emitted by the backlight is transmitted, a Fresnel lens through which the light transmitted through the light-diffusion member is transmitted, a display screen through which the light transmitted through the Fresnel lens is transmitted, and a mirror that reflects the light transmitted through the light-diffusion member toward a target space.

Abstract: An electro-optical element of the present disclosure includes a substrate, and an optical function layer. The optical function layer has a light input port, an optical branching part in which a light input side optical waveguide guiding visible light input through the light input port is connected to the one optical waveguide for monitoring and two optical modulation optical waveguides, a Mach-Zehnder optical modulation part configured to modulate visible light guided by the two optical modulation optical waveguides, a 2×1 type optical coupling part configured to couple two beams of visible light modulated by the Mach-Zehnder optical modulation part, a light output side waveguide configured to guide light coupled by the optical coupling part to a light output port, the light output port, and a monitoring light output port.

Abstract: To provide an optical modulation element capable of suppressing electrode loss at a low frequency of 50 GHz or less, and suppressing radiation loss at a high frequency of 50 GHz or more. An optical modulation element comprises: a substrate; and at least one interaction part provided on the substrate. The interaction part includes: first and second optical waveguides formed adjacent to each other on the substrate; and first and second signal electrodes provided so as to oppose the first and second optical waveguides respectively. o ground electrode is provided in a nearby region of the interaction part, and a ground electrode is provided in the vicinity of at least one of an input part and a terminal part electrically connected to each of the first and second signal electrodes.

Abstract: To provide an optical modulation element whereby reduced drive voltage and suppression of DC drift can be obtained at the same time. An optical modulation element includes: a substrate; and an optical waveguide formed of an electrooptic material film formed on the substrate and having a ridge part which is a protruding portion, and a slab part having a smaller film thickness than the ridge part 11r. The optical waveguide includes a first waveguide part having a first ridge width and a first slab film thickness and to which an RF signal is applied, and a second waveguide part having a second ridge width and a second slab film thickness different from the first slab film thickness and to which a DC bias is applied.

Abstract: A projection device includes: a plurality of light sources arranged in a first direction; a spatial modulation element that modulates incident light into image information and emits the image information; a lens that changes an optical path of light emitted from each of the plurality of light sources such that the light emitted from each light source reaches substantially the same region of an incident surface of the spatial modulation element; and a first reflective optical member that deflects the light emitted from the lens toward the spatial modulation element, the first reflective optical member having a shape that reflects light emitted from the lens so as to be incident on an arbitrary point on the incident surface of the spatial modulation element at a predetermined reference incident angle.

Abstract: This optical coupler includes a plurality of light input ports to which a plurality of visible light beams can be input, a light output port capable of coupling all of the plurality of visible light beams and outputting coupled light, an optical coupling portion to which a light-input-side optical waveguide and a light-output-side optical waveguide are connected, and at least one high-order mode removal portion provided to remove a high mode with respect to each of the plurality of visible light beams. The optical coupling portion and each high-order mode removal portion are arranged so that each of the plurality of visible light beams passes through only a high-order mode removal portion for visible light or passes through only the high-order mode removal portion for the visible light and a high-order mode removal portion for visible light having a shorter wavelength than the visible light.

Abstract: A display device includes a light guide plate including a hologram element and a light emitter that emits light to the light guide plate. In addition, the light emitter includes a light source that emits light, and a first optical body including a plurality of first lenses capable of adjusting a contour of the light emitted by the light source. An outline of each of the plurality of first lenses is analogous to a shape of the hologram element.

Abstract: The optical coupler is a multimode interference type optical coupler that couples a plurality of laser lights of different wavelengths. The optical coupler includes an optical coupling main body, two input taper portions which are tapered input ports that are disposed on the input side of the optical coupling main body and of which the width of each becomes narrower as it is away from a connection end with the optical coupling main body, and one output taper portion which is a tapered output port that is disposed on the output side of the optical coupling main body and of which the width becomes narrower as it is away from a connection end with the optical coupling main body.

Abstract: An optical modulator is a Mach-Zehnder-type optical modulator having a substrate and an optical waveguide layer including a lithium niobate film formed on the substrate. The optical waveguide layer includes a plurality of flat portions and n ridge portions arranged between the flat portions to be adjacent, where n is two or more. Each of the n ridge portions includes a main waveguide to which visible light is input, a first multimode interference waveguide through which the main waveguide is branched into a first and a second optical branch waveguide, and a second multimode interference waveguide through which the first and the second optical branch waveguide are coupled to form a coupling waveguide. Visible light beams having different wavelengths are input to the n ridge portions. The first multimode interference waveguide and the second multimode interference waveguide have shorter lengths when input light having a longer wavelength is transmitted.