Abstract: Provided is an indium phosphide substrate, a semiconductor epitaxial wafer, a method for producing an indium phosphide single-crystal ingot and a method for producing indium phosphide substrate capable of suppressing concave defects. An indium phosphide substrate has a diameter of 100 mm or less, and at least one of surfaces has zero concave defects detected in the topography channel, by irradiating a laser beam of 405 nm wavelength with S-polarized light on the surface.

Abstract: A prediction device that predicts time for a reducing agent accommodated in a container mounted on a work vehicle to freeze includes a remaining amount information acquisition unit configured to acquire remaining amount information indicating a remaining amount of the reducing agent in the container, a wall surface temperature acquisition unit configured to acquire a detection result of a wall surface temperature of the container, a reducing agent temperature acquisition unit configured to acquire a detection result of a temperature of the reducing agent, and a time calculation unit configured to calculate the time for the reducing agent to freeze based on the wall surface temperature, the reducing agent temperature, and the remaining amount information.

Abstract: An optical device includes an input waveguide and an output waveguide. The optical device includes an interference region that includes an input unit optically coupled with the input waveguide, that includes an output unit optically coupled with the output waveguide, and that has a larger waveguide width than a waveguide width of the input waveguide and a waveguide width of the output waveguide. Further, the optical device includes an unnecessary light waveguide that is included in the output unit in the interference region and that is arranged parallel to the output waveguide. The unnecessary light waveguide is a single-mode waveguide that includes a rib portion and a slab portion with a smaller thickness than a thickness of the rib portion, and that guides only a fundamental mode of light.

Abstract: An optical device includes a transition unit in which a first waveguide and a second waveguide are disposed in an overlapped manner such that a magnitude relationship of an effective refractive index between the vertical modes propagating the first waveguide and the vertical modes propagating the second waveguide is inverted at the positions of input and output. The transition unit allows, at the input, the second waveguide to be a single mode waveguide and allows, at the output, the second waveguide to be a multi-mode waveguide through which TM0 light in the maximum vertical mode and light in a higher-order mode propagate. The optical device includes a removing unit that allows the second waveguide to be a single mode waveguide through which the TM0 light propagates by removing the light in the higher-order mode from the light received from the transition unit.

Abstract: An optical waveguide device includes a pair of waveguides. One of the waveguides includes a first core formed in a conversion region and a third core formed in an exit region. The other of waveguides includes a second core formed in the conversion region and a fourth core formed in the exit region. Cross-sectional areas of the first and second cores are different from each other at an input end. Distributions of a refractive index of the first and second cores are respectively asymmetric in a perpendicular direction. A quantitative relation provided at the input end between an effective refractive index of an odd mode of TE0 and an effective refractive index of an even mode of TM0 is opposite to the quantitative relation provided at the output end. Cross-sectional areas of the third and fourth cores are different from each other at an output end.

Abstract: An optical 90-degree hybrid includes two splitters, two combiners and four arm waveguides that connect output ports of the splitters and input ports of the combiners. Each of the splitters, the arm waveguides, and the combiners is a part of an optical waveguide. The optical waveguide is configured so that the phase error generated in the splitters due to wavelength change is suppressed by the phase error generated in the arm waveguides due to the wavelength change. The optical waveguide is further configured so that the phase error generated in the splitters due to deviation of a structure parameter from a certain value (e.g., design value) is suppressed by the phase error generated in the arm waveguides due to the deviation.

Abstract: An optical waveguide device includes first and second waveguides formed parallel to each other. The first waveguide includes a first rib and a first slab. The first slab is formed in a region between the first rib and the second waveguide. The second waveguide includes a second rib, a second slab and a third slab. The second rib is provided between the second slab and the third slab. The first and second slabs are integrally formed. At one end of the optical waveguide device, a first effective refractive index that indicates an effective refractive index of a TEi mode in the first waveguide is higher than a second effective refractive index that indicates an effective refractive index of a TEj mode in the second waveguide. At another end, the first effective refractive index is lower than the second effective refractive index.

Abstract: A waveguide element includes a first waveguide and a second waveguide. The first waveguide includes a first main rib and a first slab that has a smaller thickness than that of the first main rib and in which a slab mode of light propagates. The second waveguide includes a second main rib that is optically coupled with the first main rib and in which the light propagates, a second slab that has a smaller thickness than that of the second main rib, that is optically coupled with the first slab, and in which the slab mode propagates, and a side rib that has a larger thickness than that of the second slab. The slab mode that propagates through the second slab transitions to the side rib in accordance with travel of the light that propagates in the first main rib and the second main rib.

Abstract: A tap coupler includes a mode generation unit, a separation unit, and an output unit. The mode generation unit generates, in accordance with a discontinuous portion disposed on a travelling path of signal light that is propagating, a first mode of the signal light and a second mode that is different from the first mode. The separation unit separates, when the first mode and the second mode are input from the mode generation unit, the first mode and the second mode. The output unit outputs branch light in accordance with a transition of the second mode received from the separation unit.

Abstract: An optical device has a first photonic waveguide provided on a substrate, a second photonic waveguide provided on the substrate and extending side by side with the first photonic waveguide, and a looped waveguide continuously connecting the first photonic waveguide and the second photonic waveguide on the substrate, wherein a width of at least one of the first photonic waveguide or the second photonic waveguide varies continuously along an optical axis, between a first position located at a side opposite to the looped waveguide and a second position connected to the looped waveguide, and wherein cross sections of the first photonic waveguide and the second photonic waveguide are congruent at the second position, and are incongruent at the first position.

Abstract: An optical waveguide device that is implemented between a slot waveguide and a rectangular waveguide includes: a tapered portion and a separation portion. The tapered portion includes first and second cores that are respectively coupled to cores of the slot waveguide and formed in parallel each other. The separation portion includes third and fourth cores that are respectively coupled to the first and second cores. Cross-sectional areas of the first and second cores are substantially equal each other at an input end. The cross-sectional area of the first core is larger than that of the second core at an output end. A shape of a cross section of the first core changes continuously between the input end and the output end in the tapered portion. A spacing between the third core and the fourth core is continuously extended in the separation portion.

Abstract: A prediction device that predicts time for a reducing agent accommodated in a container mounted on a work vehicle to freeze includes a remaining amount information acquisition unit configured to acquire remaining amount information indicating a remaining amount of the reducing agent in the container, a wall surface temperature acquisition unit configured to acquire a detection result of a wall surface temperature of the container, a reducing agent temperature acquisition unit configured to acquire a detection result of a temperature of the reducing agent, and a time calculation unit configured to calculate the time for the reducing agent to freeze based on the wall surface temperature, the reducing agent temperature, and the remaining amount information.

Abstract: An optical waveguide device includes a pair of waveguides. One of the waveguides includes a first core formed in a conversion region and a third core formed in an exit region. The other of waveguides includes a second core formed in the conversion region and a fourth core formed in the exit region. Cross-sectional areas of the first and second cores are different from each other at an input end. Distributions of a refractive index of the first and second cores are respectively asymmetric in a perpendicular direction. A quantitative relation provided at the input end between an effective refractive index of an odd mode of TE0 and an effective refractive index of an even mode of TM0 is opposite to the quantitative relation provided at the output end. Cross-sectional areas of the third and fourth cores are different from each other at an output end.

Abstract: An optical waveguide device includes first and second waveguides formed parallel to each other. The first waveguide includes a first rib and a first slab. The first slab is formed in a region between the first rib and the second waveguide. The second waveguide includes a second rib, a second slab and a third slab. The second rib is provided between the second slab and the third slab. The first and second slabs are integrally formed. At one end of the optical waveguide device, a first effective refractive index that indicates an effective refractive index of a TEi mode in the first waveguide is higher than a second effective refractive index that indicates an effective refractive index of a TEj mode in the second waveguide. At another end, the first effective refractive index is lower than the second effective refractive index.

Abstract: A 90-degree optical hybrid includes two optical splitters that respectively split inputted light into two beams, two optical combiners that respectively combine two beams of inputted light and thereby output two beams of interfering light respectively, and four arm waveguides that input light splitted by any of the two optical splitters into any of the two optical combiners. Each of the four arm waveguides has a bend waveguide arranged at its center and a plurality of optical waveguides including a tapered waveguide having a width that decreases toward the bend waveguide. Both ends of each of the plurality of optical waveguides are respectively in contact with a end surface of any one of the two optical splitter, the two optical combiners, the bend waveguide and the other of the plurality of optical waveguides, and each of the plurality of waveguides is the tapered waveguide or a linear waveguide.

Abstract: An optical circuit device includes a first to fourth optical couplers, wherein the first optical coupler splits a first input light into a first output beam and a second output beam with a 90-degree phase difference therebetween, and the second optical coupler splits a second input light into a third output beam and a fourth output beam with a 180-degree phase difference therebetween. The third optical coupler combines one of the first and second output beams and one of the third and fourth output beams, and outputs a first optical signal and a second optical signal having a 180-degree phase shift from each other. The fourth optical coupler combines the other of the first and second output beams and the other of the third and fourth output beams, and outputs a third optical signal and a fourth optical signal having a 180-degree phase shift from each other.

Abstract: An optical waveguide device that is implemented between a slot waveguide and a rectangular waveguide includes: a tapered portion and a separation portion. The tapered portion includes first and second cores that are respectively coupled to cores of the slot waveguide and formed in parallel each other. The separation portion includes third and fourth cores that are respectively coupled to the first and second cores. Cross-sectional areas of the first and second cores are substantially equal each other at an input end. The cross-sectional area of the first core is larger than that of the second core at an output end. A shape of a cross section of the first core changes continuously between the input end and the output end in the tapered portion. A spacing between the third core and the fourth core is continuously extended in the separation portion.

Abstract: A 90-degree optical hybrid includes two optical splitters that respectively split inputted light into two beams, two optical combiners that respectively combine two beams of inputted light and thereby output two beams of interfering light respectively, and four arm waveguides that input light splitted by any of the two optical splitters into any of the two optical combiners. Each of the four arm waveguides has a bend waveguide arranged at its center and a plurality of optical waveguides including a tapered waveguide having a width that decreases toward the bend waveguide. Both ends of each of the plurality of optical waveguides are respectively in contact with a end surface of any one of the two optical splitter, the two optical combiners, the bend waveguide and the other of the plurality of optical waveguides, and each of the plurality of waveguides is the tapered waveguide or a linear waveguide.

Abstract: An optical circuit device includes a first to fourth optical couplers, wherein the first optical coupler splits a first input light into a first output beam and a second output beam with a 90-degree phase: difference therebetween, and the second optical coupler splits a second input light into a third output beam and a fourth output beam with a 180-degree phase difference therebetween. The third optical coupler combines one of the first and second output beams and one of the third and fourth output beams, and outputs a first optical signal and a second optical signal having a 180-degree phase shift from each other. The fourth optical coupler combines the other of the first and second output beams and the other of the third and fourth output beams, and outputs a third optical signal and a fourth optical signal having a 180-degree phase shift from each other.

Abstract: An optical device has a first photonic waveguide provided on a substrate, a second photonic waveguide provided on the substrate and extending side by side with the first photonic waveguide, and a looped waveguide continuously connecting the first photonic waveguide and the second photonic waveguide on the substrate, wherein a width of at least one of the first photonic waveguide or the second photonic waveguide varies continuously along an optical axis, between a first position located at a side opposite to the looped waveguide and a second position connected to the looped waveguide, and wherein cross sections of the first photonic waveguide and the second photonic waveguide are congruent at the second position, and are incongruent at the first position.