Abstract: A wavelength demultiplexer includes a photonic circuit and a control circuit that adjusts wavelength characteristics of the photonic circuit. The photonic circuit converts two orthogonal polarized waves contained in the incident light into two same polarized waves, which are supplied to a first optical demultiplexing circuit and a second optical demultiplexing circuit provided in the photonic circuit and having the same configuration. The photonic circuit supplies a total output power of monitor lights extracted from the same positions in the first optical demultiplexing circuit and the second optical demultiplexing circuit to the control circuit. The control circuit controls a first wavelength characteristic of the first optical demultiplexing circuit and a second wavelength characteristic of the second optical demultiplexing circuit based on the total output power of the monitor lights.

Abstract: To provide an optical element that can be more easily aligned with an optical fiber, an optical element includes one grating coupler optically coupled to an optical fiber, a waveguide connected to the grating coupler, a multimode interferometer connected to the waveguide on the opposite side to the grating coupler, and a waveguide inserted between two input/output ports on the branched side of the multimode interferometer.

Abstract: An optical communication component includes three or more couplers, a pair of waveguides, a phase shifter, a detector, and a controller. Each of the couplers multiplexes two input optical signals and two-branch outputs the multiplexed optical signals. Each of the pair of waveguides connects between the couplers and outputs each of the optical signals two-branch output from one of the couplers to another one of the couplers. The phase shifter, included in each of the waveguides, adjusts a phase amount of each of the optical signals passing through the waveguides. The detector detects an amount of power of the optical signal that has been subjected to phase adjustment and that is two-branch output from a most downstream coupler, from among the couplers, located in the traveling direction of the optical signal. The controller controls, based on the detected amount of power, each of the phase shifters.

Abstract: An optical add-drop device includes optical circuits. Each of the optical circuits includes first to third sub optical circuits. Each sub optical circuit includes an input coupler, output coupler, and a phase shifter. In each of the optical circuit, two ports of the output coupler in the first sub optical circuit are respectively coupled to the input coupler in the second sub optical circuit and the input coupler in the third sub optical circuit. The output coupler in the second sub optical circuit in each of the optical circuits is coupled to a drop port or the input coupler in the first sub optical circuit in the adjacent optical circuit. The input coupler in the third sub optical circuit in each of the optical circuits is coupled to an add port or the output coupler in the third sub optical circuit in the adjacent optical circuit.

Abstract: An optical demultiplexer is disclosed that separates light including a plurality of wavelengths into light of respective wavelengths. Unit circuits are cascaded in a tree structure. In optical demultiplexer components having the same structure, a combination of arm length differences in waveguide pairs is the same with respect to the N?1 Asymmetric Mach-Zehnder interferometers in which the phase shifters are arranged, where N equals number of 2×2 couplers. In three of the optical demultiplexer components in at least one of the unit circuits, N is three or more. Each of control circuits controls the phase shifters arranged in a corresponding optical demultiplexer component of a corresponding unit circuit in order to increase or decrease a value of a function having, as an argument, a power value acquired by a monitor from among monitors arranged at four optical waveguides at an output side of the corresponding unit circuit.

Abstract: An optical semiconductor device including an optical waveguide; a light absorbing region coupled to the optical waveguide; a first conductive region and a second conductive region disposed at both sides of the light absorbing region so as to sandwich the light absorbing region; and a conductor coupled to the first conductive region and the second conductive region to let the first conductive region and the second conductive region short-circuit. With this configuration, the optical semiconductor device provides effects that absorption saturation less occurs even if the light intensity increases, so that reflection return light can be reliably suppressed without using an external power source.

Abstract: To provide an optical element that can be more easily aligned with an optical fiber, an optical element includes one grating coupler optically coupled to an optical fiber, a waveguide connected to the grating coupler, a multimode interferometer connected to the waveguide on the opposite side to the grating coupler, and a waveguide inserted between two input/output ports on the branched side of the multimode interferometer.

Abstract: An optical transmitter-receiver includes an optical integrated device in which at least an optical modulator and an optical detector are integrated as optical devices over the same substrate and an insulating layer is provided between the optical modulator and the substrate and between the optical detector and the substrate, and an electronic circuit chip that is connected to the optical integrated device and includes an electronic circuit including a ground wiring line. The optical integrated device includes a shield electrode between the optical modulator and the optical detector, and the shield electrode is provided sandwiching the insulating layer with the substrate to configure a capacitance and is connected to the ground wiring line of the electronic circuit chip.

Abstract: An optical transmission apparatus includes first and second optical waveguides to transmit light of multiple wavelengths; optical couplers on the waveguides, to couple the lights transmitted through the waveguides, so as to output the coupled light to the waveguides; phase shifters provided at preceding stages of part of the optical couplers, to change a phase shift amount of the light transmitted through the first and/or second optical waveguides, wherein the number of optical couplers in the part is greater than or equal to the number of the types of wavelengths; a monitor to monitor the intensity of the light output to the second optical waveguide via the optical coupler at the last stage; and a controller to control the phase shifters by changing the phase shift amount for each of the phase shifters in a direction in which the output of the monitor decreases.

Abstract: An optical device includes a light-emitting element; an electronic circuit chip; a substrate on which the light-emitting element and the electronic circuit chip are mounted; a first electrode formed on a first mounting surface of the light-emitting element on the substrate; and a second electrode formed on a second mounting surface of the electronic circuit chip on the substrate. The first electrode and the second electrode have the same structure.

Abstract: An optical demultiplexer has at least one unit circuit formed by three AMZs having a same arm length difference and cascaded in a tree structure in which two output ports of the 1st AMZ are connected to the 2nd AMZ and the 3rd AMZ, respectively, wherein the unit circuit has first and second monitors connected to the first and second output ports of the 2nd AMZ, and third and fourth monitors connected to the first and second output ports of the 3rd AMZ, a first control circuit controlling the transmissivity of the 1st AMZ so as to increase the monitoring result of the second and fourth monitors, a second control circuit controlling the transmissivity of the 2nd AMZ to decrease the monitoring result of the first monitor, and a third control circuit controlling the transmissivity of the 3rd AMZ to decrease the monitoring result of the third monitor.

Abstract: A semiconductor light-emitting device includes an active layer including quantum dots, a diffraction grating, a low-reflectance film disposed at a light-emitting end of the active layer, and a high-reflectance film disposed at another end of the active layer and having an optical reflectance higher than an optical reflectance of the low-reflectance film.

Abstract: A modulated light source includes a reflective semiconductor optical amplifier including a mirror at a first end of the reflective semiconductor optical amplifier, a modulator configured to modulate a central wavelength, a first mirror configured to reflect light transmitted by the modulator, an optical filter disposed between a second end of the reflective semiconductor optical amplifier and the modulator, and a second mirror configured to reflect part of incoming light and to transmit the other part of the incoming light. The reflective semiconductor optical amplifier, the optical filter, and the second mirror configure a Fabry-Perot laser. The first mirror is configured to feed light emitted from the Fabry-Perot laser back to the Fabry-Perot laser, and the modulated light source is configured to select light corresponding to one of longitudinal modes oscillated by the Fabry-Perot laser, to modulate the selected light, and to output the modulated light.

Abstract: According to one embodiment, a semiconductor light-emitting element includes a ring-shaped light-emitting portion provided on a substrate, a mode-control light waveguide of Si provided on an upper or a lower surface side of the light-emitting portion, and including at least two portions located close to the light-emitting portion, and an output light waveguide of Si provided on the upper or the lower surface side, and including a portion located close to the light-emitting portion. The mode-control light waveguide has a structure for coupling light traveling in one of a clockwise circulating mode and a counterclockwise circulating mode, and feeding back the light in the other of the clockwise circulating mode and the counterclockwise circulating mode.

Abstract: The optical waveguide element has a first optical waveguide core; and a second optical waveguide core. In the optical waveguide element, the first optical waveguide core includes a first coupling portion configured to propagate any one polarized wave of a TE polarized wave and a TM polarized wave of a kth-order mode, the other polarized wave of an hth-order mode, and the other polarized wave of a pth-order mode, and a first Bragg reflector connected to the first coupling portion. The second optical waveguide core includes a second coupling portion.

Abstract: Provided is a wavelength filter including: an optical waveguide core that includes n (n is an integer greater than or equal to 2) number of mode conversion parts and n?1 number of cavity parts that are alternately connected to each other in series; and cladding that surrounds the optical waveguide core. The mode conversion parts convert light having a specific wavelength of a p-order mode (p is an integer satisfying p?0) into light of a q-order mode (q is an integer satisfying q>p) and reflect the light. The cavity parts match phases of the light having the specific wavelength of the p-order mode propagating through the cavity part.

Abstract: An electro-optic device includes a first semiconductor layer including the rib-type waveguide, which includes a rib part and a first slab part, which extends in a first direction from the rib part; a dielectric layer, which is formed on the rib part; a second semiconductor layer, which extends in a second direction, which is opposite to the first direction, from an upper surface of the dielectric layer; a first high-concentration impurity region, which is formed in the first semiconductor layer to be in contact with the first slab part on the first direction side; and a second high-concentration impurity region, which is formed in a region of the second semiconductor layer on the second direction side. The second high-concentration impurity region is formed in a region other than a region overlapping the first semiconductor layer in a lamination direction.

Abstract: The invention relates to an optical fiber mounted photonic integrated circuit device, wherein the tolerance for positioning in terms of the coupling between the single mode optical fibers and the optical waveguides provided on the photonic integrated circuit device is increased. An optical waveguide core group is provided in such a manner where a plurality of optical waveguide cores having a portion that is tapered in the direction of the width within a plane are aligned parallel to each other at intervals that allow for mutual directional coupling and that are narrower than the width of the core of the single mode optical fiber, and the inclined connection end surface of the single mode optical fiber and the upper surface of an end portion of the optical waveguide cores face each other for coupling.

Abstract: An optical wiring module includes an optical wiring substrate on which an optical waveguide having a light input/output part is formed, and a fiber holder mounted on the optical wiring substrate, the fiber holder being configured to hold an optical fiber. The optical wiring substrate includes a hydrophobic film having an opening at a position corresponding to the light input/output part and a first adhesive layer disposed within the opening, and the optical fiber is optically coupled to the light input/output part via the first adhesive layer.

Abstract: An optical device includes an optical waveguide provided on a principal surface of a substrate. The optical waveguide includes a core and a cladding provided around the core. The cladding is configured by a substance having a refractive index smaller than 71.4% of the refractive index of the core. The core has constituent atoms substantially forming a diamond lattice structure. The optical waveguide has a light input/output part through which a light beam is input and/or output. The light input/output part decreases stepwise in thickness towards an output end while tapering down in its width. The core is provided in the light input/output part to have a (111) plane or an equivalent plane to the (111) plane exposed on a face of a riser of the stepwise thickness of the light input/output part.