Abstract: There is provided a waveguide type optical coupler that maintains a constant branching ratio in a wide wavelength region without wavelength dependency and polarization dependency. A waveguide type optical coupler includes a Mach-Zehnder interferometer that includes two arm waveguides between two directional couplers. In the waveguide type optical coupler, waveguide widths of the two waveguides in a coupling portion of the directional coupler are different from each other.

Abstract: A wavelength monitoring apparatus includes a wavelength monitoring circuit. The wavelength monitoring circuit includes: a split circuit that splits an input optical signal into two; an optical delay circuit that applies a delay time difference to the two split optical signals; and a two-input two-output optical multiplexer/demultiplexer circuit that outputs a result of applying multiplexing interference to the optical signals to which the delay time difference has been applied. The wavelength monitoring apparatus further includes photoelectric conversion elements that perform photoelectric conversions on the two optical signals output from the wavelength monitoring circuit so as to output electrical signals.

Abstract: In a waveguide having a given ?, a low-loss waveguide bend is realized while the curvature radius is kept small. In an optical waveguide in which a first waveguide and a second waveguide are connected, a clothoid tapered waveguide bend is inserted between the first waveguide and the second waveguide. In the clothoid tapered waveguide bend, the waveguide width continuously changes from a first waveguide width at a connection point of the first waveguide to a second waveguide width at a connection point of the second waveguide, the curvature radius continuously changes from a first curvature radius at the connection point of the first waveguide to a second curvature radius at the connection point of the second waveguide, the first waveguide width and the second waveguide width are different from each other, and the first curvature radius and the second curvature radius are different from each other.

Abstract: The present invention realizes an optical signal processing device that enables using a thermal oxidation silica film as the under clad of a silica PLC while also increasing the thickness of the under clad and reducing the time required for film growth during manufacturing. The optical signal processing device is formed as a planar optical circuit that includes an optical waveguide formed on a silicon substrate, and has a phase modulation element that employs a thermo-optical effect. A plurality of silica films are provided between a core of the optical waveguide and the silicon substrate, and at least one of the silica films was formed by thermal oxidation.

Abstract: In order to reduce the number of power driving elements, an optical signal processing device includes a control unit, a current generation unit, a connection portion, and an optical signal processing unit, the current generation unit includes one or a plurality of power driving elements s, the optical signal processing unit is an optical waveguide on a substrate, and a plurality of driven elements are connected in parallel to an identical one of the plurality of power driving elements and are driven.

Abstract: An optical phase shifter in which a phase shift amount is kept constant in a wide wavelength region is provided. One aspect is the optical phase shifter constituting of two waveguides of a basic width, and configured so that two lights propagating through each waveguide have a phase difference, including a different type waveguide arranged in at least one of the two waveguides and having a waveguide width different from the basic width, and a configuration of the different type waveguide and a parameter of the two waveguides and different type waveguide are optimized.

Abstract: To provide an optical signal processing device capable of reducing the crosstalk while narrowing the space between switch elements for downsizing, the optical signal processing device includes a plurality of input optical waveguides, a plurality of output optical waveguides, a plurality of optical waveguide elements arranged between the plurality of input optical waveguides and the plurality of output optical waveguides, and a connection optical waveguide. The connection optical waveguide positioned closely to the optical waveguide element is differentiated in propagation constant from the optical waveguide configuring the closely arranged optical waveguide element. The connection optical waveguide positioned closely to the optical waveguide element is a connection optical waveguide having one end or both ends connected to the optical waveguide element, or a connection optical waveguide having both ends not connected to the optical waveguide elements.

Abstract: The positions at which electrode pads are arranged can be made more flexible, and electrical interconnects to be installed can be reduced. In addition, the degree of integration of a chip increases, making it possible to realize a large-scale device (optical switch etc.). In an optical module of the present invention, an interposer (an electrical connection intermediary component with electrode pins attached onto upper and lower faces in an array) is laid over a chip that includes a device configured by using a planar lightwave circuit (PLC) fixed onto a fixing metal plate, and a control substrate for driving the device is laid over the interposer. These components are mechanically fixed by a fixing screw or the like, and the electrode pads of the chip and the control substrate are connected to each other via the interposer.

Abstract: A wavelength monitoring circuit obtains a light output proportional to only an input optical signal, independent of wavelength, by adding a light split circuit to the configuration in the related art, or changing the light split circuit to a light trifurcation circuit. In addition, wavelength monitoring with high accuracy is possible while improving the resistance to noise. The extraction of the light output proportional to only the input optical signal is performed by a light split circuit for input light at the top stage of the wavelength monitoring circuit or a light split circuit for interference in a stage in the middle of the circuit. The changed light split circuit causes the MZI included in the wavelength monitoring circuit to operate in a state of losing the balance of the configuration or the optical signal level, and increases the signal level near the bottom portion of the transmission characteristics.

Abstract: The invention provides a planar optical waveguide circuit capable of preventing part of the input signal light that has not been combined in the waveguide and propagates as leaked light from interfering with the output signal. A planar optical waveguide circuit having an optical waveguide embedded in a cladding layer includes: a plurality of parallel output optical waveguides configured to emit light from a same end face; a groove having a reflective interface formed at an angle of +45 degrees relative to the output optical waveguides and configured to reflect leaked light propagating in the cladding layer; and a groove having a reflective interface formed at an angle of ?45 degrees, the reflective interface formed at an angle of +45 degrees, the output optical waveguide, and the reflective interface formed at ?45 degrees being arranged repeatedly in that order.

Abstract: There is provided an optical signal processing device capable of RC in a complex space using optical intensity and phase information. An optical modulator controlled by an electric signal processing circuit modulates laser light, which is emitted from a laser light source, at a modulation period either or both of the intensity and phase values of the optical electric field. On the other hand, an input signal is also modulated by the optical modulator at a modulation period in the time domain so as to be an input signal. The converted input signal passes through an optical transmission path and enters an optical circulation circuit via an optical coupler. Part of the circulating light is branched into two by an optical coupler, and the branched light is converted into a complex intermediate signal at a coherent optical receiver. This complex intermediate signal demodulated at the coherent optical receiver is computed at an electric signal processing circuit, and thereby the operation as RC can be performed.

Abstract: An optical switch is configured by providing a planar lightwave circuit layer on a top surface of a Si substrate. The circuit layer forms, on the top surface of the substrate, an optical waveguide including an underclad layer, an optical waveguide core, and an overclad layer. The optical waveguide is provided to have a structure configuring a Mach-Zehnder interferometer. A heater is provided at a position just above an arm of the core on the top surface of the clad layer, and power supply electric wires are electrically connected to both ends of the heater. In a local portion including an interface between the clad layer and the top surface of the substrate, trench structure portions as concave grooves are provided.

Abstract: In an optical circuit divided into a plurality of partial circuits, an optical waveguide having a low optical loss at a connection portion is provided. A photomask in which a waveguide pattern of an optical circuit is divided into a plurality of regions and drawn, the photomask including a waveguide pattern for drawing a joint region in which a waveguide width changes as a waveguide goes toward an outer peripheral portion, to connect a plurality of the waveguides divided and drawn to each other, in which the waveguides are connected to each other by overlapping the joint regions of two of the photomasks and performing exposure.

Abstract: In a waveguide having a given ?, a low-loss waveguide bend is realized while the curvature radius is kept small. In an optical waveguide in which a first waveguide and a second waveguide are connected, a clothoid tapered waveguide bend is inserted between the first waveguide and the second waveguide. In the clothoid tapered waveguide bend, the waveguide width continuously changes from a first waveguide width at a connection point of the first waveguide to a second waveguide width at a connection point of the second waveguide, the curvature radius continuously changes from a first curvature radius at the connection point of the first waveguide to a second curvature radius at the connection point of the second waveguide, the first waveguide width and the second waveguide width are different from each other, and the first curvature radius and the second curvature radius are different from each other.

Abstract: A waveguide bend which has low loss while keeping the curvature radius small in a waveguide with a given A is realized. An optical waveguide has a straight waveguide and a waveguide bend connected to each other, and tapered waveguide bends inserted between the straight waveguide and the waveguide bend, a curvature radius of the tapered waveguide bend being equal to a curvature radius of the waveguide bend, a waveguide width of the tapered waveguide bend changing continuously from the waveguide width of the straight waveguide at the connection point to the waveguide width of the waveguide bend. A waveguide width of the waveguide bend is larger than a waveguide width of the straight waveguide at a connection point and the tapered waveguide bend and the straight waveguide are connected with an optical axis of the tapered waveguide bend and an optical axis of the straight waveguide being offset.

Abstract: An optical switch is configured by providing a planar lightwave circuit layer on a top surface of a Si substrate. The circuit layer forms, on the top surface of the substrate, an optical waveguide including an underclad layer, an optical waveguide core, and an overclad layer. The optical waveguide is provided to have a structure configuring a Mach-Zehnder interferometer. A heater is provided at a position just above an arm of the core on the top surface of the clad layer, and power supply electric wires are electrically connected to both ends of the heater. In a local portion including an interface between the clad layer and the top surface of the substrate, trench structure portions as concave grooves are provided.

Abstract: In order to reduce the number of power driving elements, an optical signal processing device includes a control unit, a current generation unit, a connection portion, and an optical signal processing unit, the current generation unit includes one or a plurality of power driving elements s, the optical signal processing unit is an optical waveguide on a substrate, and a plurality of driven elements are connected in parallel to an identical one of the plurality of power driving elements and are driven.

Abstract: An optical signal processing device is described herein for reducing electric wirings in an optical switch or an optical filter realized using an optical waveguide. The optical signal processing device includes an optical waveguide formed on a substrate. In the optical signal processing device, the optical waveguide includes at least one input port and at least one output port, a plurality of driven elements are provided including a phase shifter that produces a phase shift to an optical signal from the input port, each of the driven elements includes at least two control terminals, control wirings are provided to have control signals being time-division synchronized applied between the two control terminals, and the control wiring for accessing the driven element is shared by the plurality of driven elements.

Abstract: The invention provides a planar optical waveguide circuit capable of preventing part of the input signal light that has not been combined in the waveguide and propagates as leaked light from interfering with the output signal. A planar optical waveguide circuit having an optical waveguide embedded in a cladding layer includes: a plurality of parallel output optical waveguides configured to emit light from a same end face; a groove having a reflective interface formed at an angle of +45 degrees relative to the output optical waveguides and configured to reflect leaked light propagating in the cladding layer; and a groove having a reflective interface formed at an angle of ?45 degrees, the reflective interface formed at an angle of +45 degrees, the output optical waveguide, and the reflective interface formed at ?45 degrees being arranged repeatedly in that order.

Abstract: To provide an optical signal processing device capable of reducing the crosstalk while narrowing the space between switch elements for downsizing, the optical signal processing device includes a plurality of input optical waveguides, a plurality of output optical waveguides, a plurality of optical waveguide elements arranged between the plurality of input optical waveguides and the plurality of output optical waveguides, and a connection optical waveguide. The connection optical waveguide positioned closely to the optical waveguide element is differentiated in propagation constant from the optical waveguide configuring the closely arranged optical waveguide element. The connection optical waveguide positioned closely to the optical waveguide element is a connection optical waveguide having one end or both ends connected to the optical waveguide element, or a connection optical waveguide having both ends not connected to the optical waveguide elements.