Abstract: An optical semiconductor device includes a first optical device formed on a silicon substrate having a first surface, and a second optical device including a compound semiconductor, mounted on the first optical device, and having a second surface facing the first surface. The first optical device includes a first protrusion that protrudes toward the second surface, and a portion of the second surface makes contact with the first protrusion. In a plan view, the first protrusion is located on an inner side of an outer edge of the second optical device.

Abstract: An optical device includes a generator, a light emitter, a modulator, an optical amplifier, a current source, a storage, and a controller. The generator generates an electric signal of a multilevel amplitude modulation method. The light emitter emits laser light. The modulator modulates the laser light using the electric signal and outputs an optical signal. The optical amplifier optically amplifies the modulated optical signal according to a drive current. The current source adjusts the drive current to be supplied to the optical amplifier. The storage previously stores an information with respect to input-output characteristics of the optical signal in the optical amplifier relative to drive current value of the drive current. The controller acquires, from the storage, the input-output characteristics corresponding to the drive current value of the drive current supplied to the optical amplifier and controls the electric signal based on the acquired input-output characteristics.

Abstract: A device includes an emitter that emits transmission light with P polarization, a receiver that receives reception light, a transmission port that outputs the transmission light, a reception port that inputs the reception light, and an adjuster that polarizes the reception light received to S polarization. The device includes a filter that outputs the transmission light with P polarization received from the emitter by allowing the transmission light to propagate through inside a propagation path, and that outputs the reception light with S polarization received from the adjuster by allowing the reception light to propagate through inside the path. The device includes a polarizer that is arranged between the filter and the emitter and between the filter and the receiver, outputs the transmission light with P polarization received from the emitter to the filter, and outputs the reception light with S polarization received from the filter to the receiver.

Abstract: An optical device has a waveguide circuit, a transmitter that transmits transmitted light to the waveguide circuit, and a receiver that receives received light from the waveguide circuit. The waveguide circuit has an optical waveguide, a wavelength combiner and splitter, and a mode filter. The optical waveguide includes a first port where the transmitted light output from the transmitter is input to and a second port where the transmitted light is output from, guides the transmitted light, and guides the received light input from the second port. The wavelength combiner and splitter is arranged in the optical waveguide between the first port and the second port. The mode filter removes a higher-order mode of the received light input by use of the wavelength combiner and splitter and includes a third port that outputs the received light having the higher-order mode removed from the received light, to the receiver.

Abstract: An optical detector includes a photodetector that converts signal light into an electric signal, and a mode filter. The photodetector includes a first port to which signal light of a first mode is input, and a second port to which signal light of a second mode is input. The mode filter includes a third port connected to the first port, and a fourth port connected to the second port. The mode filter passes the signal light of the first mode towards the first port to be output from the third port, passe the signal light of the second mode towards the second port to be output from the fourth port, removes the signal light of the second mode from the first port input from the third port, and removes the signal light of the first mode from the second port input from the fourth port.

Abstract: A wavelength tunable laser device includes: a first mirror; a second mirror; an optical amplifier provided between the first mirror and the second mirror; a wavelength tunable filter provided between the first mirror and the second mirror; and an optical waveguide coupling the optical amplifier and the wavelength tunable filter. The optical waveguide includes a first waveguide formed with a first width and a second waveguide formed with a second width wider than the first width.

Abstract: An optical modulator includes a first coupler that splits signal light into two beams of light, a first waveguide that is connected to one output of the first coupler, a second waveguide that is connected to another output of the first coupler, and a second coupler that couples signal light coming from the first waveguide and the second waveguide and outputs coupled light. The first waveguide includes a first input-side arm waveguide, a first output-side arm waveguide, and a first folded waveguide. The second waveguide includes a second input-side arm waveguide, a second output-side arm waveguide, and a second folded waveguide. The first and second input-side arm waveguides and the first and second output-side arm waveguides are waveguides that include a material with high EO characteristics. The first and second folded waveguides are waveguides that include a material (SiN) with a low refractive index.

Abstract: A photodetector has a substrate, a light input layer formed as a first semiconductor over the substrate, the first semiconductor being transparent to a wavelength being used, and a light absorption layer formed as a second semiconductor on the light input layer, the second semiconductor having a bandgap smaller than that of the first semiconductor. The light absorption layer has a first region doped with a first conductivity-type impurity, a second region doped with a second conductive-type impurity different from the first conductive-type impurity, and an undoped region between the first region and the second region. The first region, the undoped region and the second region are arranged in a direction parallel to the substrate. The light absorption layer has a region having an effective refractive index higher than the rest of the light absorption layer between the first region and the second region.

Abstract: An optical device includes a photonic integrated circuit chip and a resin member. The photonic integrated circuit chip has a first surface on which an optical circuit and first electrical wiring are formed. The resin member makes contact with at least part of the photonic integrated circuit chip. A dam structure is formed along an outer circumference of the first surface. At least part of the optical circuit is formed using a different material that is different from a material of the photonic integrated circuit chip. The resin member seals the photonic integrated circuit chip without sealing an area on an inner side with respect to the dam structure of the first surface. Second electrical wiring is formed on a surface of the resin member. The second electrical wiring is electrically connected to the first electrical wiring.

Abstract: A control device has an attenuator, a monitor that measures a peripheral temperature around the attenuator, and a controller. The controller stores a first function approximating a relation between amounts of attenuation and driving current values at a standard temperature, and a second function for calculating a temperature correction factor that corrects a driving current value between the peripheral temperature and the standard temperature. The controller calculates, by the first function, a driving current value at the standard temperature, and calculates, by the second function, a temperature correction factor. Based on the driving current value at the standard temperature and calculated by the first function and the temperature correction factor calculated by the second function, the controller calculates a driving current value for obtaining the set amount of attenuation at the peripheral temperature. The controller controls driving of the attenuator based on the driving current value calculated.

Abstract: An optical integrated circuit module includes an optical integrated circuit element that includes as optical waveguide that is made by using an organic electro-optical material, and a cover that seals, as vacuum sealing, at least the optical waveguide that is disposed on the optical integrated circuit element. In addition, the optical integrated circuit module includes an oxygen getter that is provided in an inner part of the cover and that absorbs oxygen contained in the inner part of the cover.

Abstract: An optical device includes a substrate, a tapered waveguide that is arranged in a first layer on the substrate and that has a waveguide width that gradually increases from input to output, a rib waveguide that is arranged in a second layer on the substrate, where the second layer is different from the first layer, and overlaps with the tapered waveguide in a plane direction. The rib waveguide includes a rib that has a core width that gradually increases from the input to the output, and slabs that are arranged on both sides of the rib and that have slab widths that gradually increase from the input to the output.

Abstract: An optical device includes a substrate, an optical waveguide, and a first chip and a second chip each of which is mounted on the substrate, includes a material having an electro-optical effect that is higher than that of the substrate, and includes a crystal axis in which the strongest electro-optical effect is exerted. The first chip includes a first electrode that is arranged in the vicinity of an input side first waveguide, and that applies an electric field flowing in the same direction as an orientation of the crystal axis of the first chip to the input side first waveguide. The second chip includes a second electrode that is arranged in the vicinity of an output side first waveguide, and that applies an electric field flowing in the same direction as an orientation of the crystal axis of the second chip to the output side first waveguide.

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 device includes a first coupler, a second coupler, and a monitor. The first coupler includes a first input port, a first bar port, and a first cross port, and largely taps signal light on a short wavelength side from the first input port to the first bar port. The second coupler includes a second input port, a second bar port, and a second cross port, and largely taps signal light on a long wavelength side from the second input port to the second cross port. The monitor is connected to one of the first bar port and the second cross port, and monitors signal light that is output from one of the first bar port and the second cross port.

Abstract: An optical device includes a channel waveguide that has a waveguide width that increases in a tapered manner, and a rib waveguide that is connected to a side at which the waveguide width of the channel waveguide is increased and that includes a rib portion and slab portions. The rib waveguide includes a tapered waveguide in which a rib width of the rib portion increases in a tapered manner with distance from a part at a side at which the channel waveguide is connected.

Abstract: An optical integrated device includes a first chip having a step portion, and a second chip that is mounted on the step portion, and that is optically connected to the first chip. The first chip includes an optical waveguide including a material having a high electro-optic effect compared to a material of the second chip. The optical integrated device includes a first inclined surface that is formed on a wall surface on a side on which the optical waveguide and the second chip are optically connected in the step portion, and a second inclined surface that is formed on an end surface of the second chip on a side on which it is mounted within the step portion, and that abuts on the first inclined surface facing the first inclined surface.

Abstract: An optical device includes a rib optical waveguide including N parallel waveguides connected to outputs of a split coupler of 1 input×N outputs, and a first electrode and a second electrode that are connected to the rib optical waveguide. The rib optical waveguide includes a non-conductive slab region formed between the waveguides, a P-doped region and an N-doped region. The P-doped region is formed in a first slab region outside one of outermost waveguides of the N waveguides and is connected to the first electrode. The N-doped region is formed in a second slab region outside the other one of the outermost waveguides of the N waveguides and is connected to the second electrode.

Abstract: An optical module includes an optical transmitter that outputs transmission light to a transmission path port by using an optical signal, and an optical receiver that receives reception light received from the transmission path port by using the optical signal. The optical module includes an optical fiber that is a single mode optical fiber (SMF), that connects the optical transmitter and the optical receiver to the transmission path port, and through which the optical signal propagates. The wavelength of the optical signal is equal to or less than a cutoff wavelength of the optical fiber. The optical module incudes a holding mechanism that holds a bending shape of the optical fiber having a predetermined radius of curvature and through which only a basic mode included in the optical signal propagates.

Abstract: A disclosed semiconductor photodetector includes a first semiconductor layer having a first refractive index and a first band gap; a second semiconductor layer formed on the first semiconductor layer, the second semiconductor layer having a second refractive index and a second band gap; a first electrode; and a second electrode. The second refractive index is greater than the first refractive index, and the second band gap is smaller than the first band gap. The first semiconductor layer includes a p-type first region, an n-type second region, and a non-conductive third region between the first region and the second region. The second semiconductor layer includes a p-type fourth region in ohmic contact with the first electrode, an n-type fifth region in ohmic contact with the second electrode, and a non-conductive sixth region between the fourth region and the fifth region.