Abstract: A problem is to provide a planar lightwave circuit optical device capable of facilitating mounting of connection to a printed circuit board and realizing downsizing of a device chip. A planar lightwave circuit optical device of the present invention is characterized by mounting an electrical connector (FPC connector) by means of soldering on an electrode pad of an electrical wire connected to an electrical drive unit (such as a heater) in a device formed by using a planar lightwave circuit (PLC).

Abstract: According to the present disclosure, it is possible to realize an optical communication system in which a relay-type PSA and homodyne detection are efficiently combined using a single phase synchronization mechanism. Intensity noise and phase noise can be suppressed to a very low level, and accurate transmission of signals with increased multiplicity is enabled. By utilizing the features of the PSA to extract the phase of a single carrier using the sum frequency light of the signal light and its phase-conjugated light, the number of pilot carriers can be reduced compared to the configuration of the conventional optical communication system, and it is possible to suppress unnecessary nonlinear noise.

Abstract: A highly-efficient ridge waveguide includes a base substrate of a single-crystal and a core substrate made of a nonlinear optical medium, the base substrate and the core substrate being directly bonded, and includes a thin film layer formed on a surface of the core substrate on the upper side of a periodically polarization-reversed structure, and becomes a wavelength conversion element. A direct bonding method through thermal diffusion is applied to bonding. The core substrate has a ridge structure formed in a light propagating direction and a reversed structure formed by processing this. A surface of the core substrate is ground and a thin film layer is formed on the ground surface. A core formed by digging a core layer of the core substrate in an unbonded state is provided on an upper surface of an undercladding layer of the base substrate in a bonded state. Two side surfaces of the core are in contact with an air layer.

Abstract: An optical module capable of suppressing deterioration of an adhesive layer and having a resistance to high-power light even when high-energy light propagates is configured by connecting an optical fiber to a PLC. The optical fiber is provided with an etching face at a recessed area where a cladding region on its side face is partially removed over a length L in a light propagation direction from an input/output end connected to the PLC, and the PLC is also provided with an etching face at a recessed area where a cladding layer is partially removed over the length L in the light propagation direction from an input/output end connected to the optical fiber. The adhesive layer made of a UV cured resin is interposed between the etching faces to bond and fix the etching faces to each other, and a core of the optical fiber and a core layer of the PLC form a directional coupler for linearly dispersing energy density.

Abstract: With a wavelength conversion device based on a nonlinear optical effect, when arrayed waveguides including an intended nonlinear waveguide are fabricated, unwanted slab waveguides are inevitably formed. The slab waveguides can cause an erroneous measurement in the selection of a waveguide having desired characteristics from the arrayed waveguides. The erroneous measurement can lead to redoing steps for fabricating the wavelength conversion device and a decrease in the yield and inhibit the evaluation of the characteristics in selection of the waveguide and the subsequent fabrication of the wavelength conversion device from being efficiently performed. A wavelength conversion device according to the present invention includes a plurality of waveguides formed on a substrate, and a plurality of slab waveguides that are arranged substantially in parallel with and spaced apart from the plurality of waveguides, and a guided light attenuator is formed in each of the slab waveguides.

Abstract: A wavelength conversion device that restrains output power of light that has a wavelength converted from reducing due to a pyroelectric effect when a temperature of a wavelength conversion element including a ferroelectric substrate is changed is a wavelength conversion device that includes, in a casing, the wavelength conversion element, a temperature control element that controls a temperature of the wavelength conversion element, a static elimination mechanism and a surface potential measurement mechanism, and eliminates static electricity by driving the static elimination mechanism when the surface potential measurement mechanism detects a change in surface potential of the wavelength conversion element.

Abstract: To manufacture an optical waveguide including a substrate, a lower cladding layer formed on the substrate, a core layer formed on the lower cladding layer, a sinking prevention layer formed to cover the core layer and the lower cladding layer, and an upper cladding layer formed on the sinking prevention layer, in which the sinking prevention layer is composed of a material having a higher melting point than that of a material composing the lower cladding layer.

Abstract: An optical signal processing device includes: a light source which generates a fundamental wave light; an optical modulator which modulates the fundamental wave light, and generates a fundamental wave light having a plurality of carriers synchronized in phase; an optical filter which passes through required components among the plurality of carriers; a first second-order nonlinear optical element on which a light which passes through the optical filter is incident, and which generates a second harmonic of the fundamental wave light; and a second second-order nonlinear optical element on which a signal light and the second harmonic are incident, the second second-order nonlinear optical element performing nondegenerate parametric amplification, wherein the second second-order nonlinear optical element has an output unit for picking up a wavelength converted light corresponding to difference in frequency between the signal light and the second harmonic or an amplified light of the signal light.

Abstract: There is provided an optical waveguide chip. In the optical waveguide chip, an optical waveguide circuit includes a substrate, a lower clad layer laminated on the substrate, a core layer that is laminated on the lower clad layer and corresponds to a propagation path of an optical signal, and an upper clad layer laminated on the core layer; the upper and lower clad layers in a region that does not correspond to the propagation path of the optical signal are removed across to an edge of the chip; the region from which the upper and lower clad layers have been removed is filled with a light absorbing material; and a height of the filled light absorbing material is higher than a height of an uppermost surface of the upper clad layer.

Abstract: A wavelength conversion optical element using a nonlinear optical effect of a device structure in which wavelength conversion efficiency rises as targeted when the length of a waveguide is increased is provided. The element adopts a waveguide structure using lithium niobate of a second-order nonlinear optical material. Wavelength conversion regions are formed to correspond to two linear waveguides extending in parallel to each other on a plane of the planar structure and correspond to the lengths of the two linear waveguides. One end side of the linear waveguide is an incident side of excitation light and one end side of the linear waveguide is an emission side of wavelength converted light. The linear waveguides excluding the incident side and the emission side are joined by a bent waveguide.

Abstract: Provided is a wavelength conversion element capable of achieving highly efficient wavelength conversion, without relying on a method of applying electric fields. A wavelength conversion element is formed of a second-order nonlinear optical crystal and has a z-axis, running along a direction of spontaneous polarization, within a substrate plane. The wavelength conversion element includes a waveguide in which, when a plurality of circles having their centers on a straight line parallel to the z-axis and having the same radius are depicted so that circumferences of the plurality of circles contact each other, semicircular waveguides corresponding to one semicircles of the circumferences with the straight line as a boundary, are alternately connected.

Abstract: A wavelength conversion apparatus using a nonlinear optical medium having a periodically poled structure is operated at an optimal temperature in a stable manner. The wavelength conversion apparatus includes a wavelength converter using a nonlinear optical medium and a controller for controlling temperature of the wavelength converter. The wavelength conversion apparatus further includes a first optical branch coupler for branching part of output light from the wavelength converter, and first and second wavelength separation filters for separating and outputting, from part of the output light, each of two light components generated by parametric fluorescence in the wavelength converter. The controller controls the temperature of the wavelength converter on the basis of difference in light intensity of the two light components.

Abstract: The present invention provides a configuration of a novel optical transmitter which outputs stable PDM signals. The novel optical transmitter generates phase conjugate light using a single second-order non-linear optical element included in a phase conjugate light generator with a looped configuration. A relative phase of main signal light with respect to excitation light and phase conjugate light of the main signal light stabilizes between two polarized components, and a PDM signal including a pair of a polarization-multiplexed signal and phase conjugate light in a stable phase state can be generated and transmitted. The present invention can provide an optical transmitter that generates a PDM signal in which a variation in a phase between quadrature polarized waves is suppressed. By stabilizing quality of a PDM transmission signal on a side of the optical transmitter, a phase sensitive amplifier in a polarization diversity configuration can be operated in a stable manner.

Abstract: A configuration of an excitation light generation device for providing an excitation light having a good SN ratio to a PSA is disclosed. Further, a configuration of a relay amplifier of the PSA including the excitation light generation device is also shown. The following disclosure includes the excitation light generation device, an optical amplification device including the excitation light generation device, and an optical transmission system. More specifically, the excitation light generation device for maintaining the SN ratio of the excitation light in a high state by utilizing an optical sensitive amplification function with respect to the excitation light generated by an optical phase lock loop is disclosed. The excitation light generation device of the present disclosure generates a local oscillation excitation light using the OPLL and having a sufficiently high SN ratio, which makes an inherent low noise operation of the PSA possible even to a signal light having a high SN ratio.

Abstract: There is provided an optical wavelength suppressed in sinking of the core layer into the underlying cladding layer in the heat treatment of the manufacturing process, thereby enabling the reduction of the loss of the visible light waveguide, and suppressed in variations in the substrate plane in the optical waveguide shape. The optical waveguide includes: a substrate, an underlying cladding layer formed on the substrate, an etching stopping layer formed on the underlying cladding layer, a core layer formed on the etching stopping layer, and an overlying cladding layer formed on the core layer and the etching stopping layer. The optical waveguide is characterized in that the etching stopping layer includes a material having a smaller etching rate than that of a material forming the core layer, and having a higher softening point than that of the material forming the core layer.

Abstract: A heartbeat detection device including a time difference value calculation unit to calculate a time difference value from a sampling data string of an electrocardiographic waveform of a living body, an index value calculation unit to calculate an index value for heartbeat detection based on the time difference value, a threshold setting unit to determine whether a peak of the index value exceeding a threshold can be detected, to calculate, a threshold candidate based on an average value of the predetermined number of the most recent peaks among these peaks. A threshold candidate is set as a new threshold when the threshold candidate has a value equal to or less than a threshold limit value. A heartbeat time determination unit sets the sampling time of the peak as the heartbeat time when the peak of the index value exceeding the threshold is detected.

Abstract: An end portion structure of a transmission line of the present invention is a structure in which a protective film with a thickness of 0.5 ?m to 3.0 ?m is formed on the end surface of the transmission line in place of an end cap formed in an end portion of a transmission line in the related art, and no adhesive is used in a portion through which light passes. The protective film on the end surface works to suppress a bulge of the core. The thickness of the protective film is significantly thinner than the end cap, and thus waveguides facing each other can be brought close to each other. It is possible to reduce the connection loss between two fibers or waveguides facing each other to be 0.5 dB or less. Since no adhesive is used, there is no loss increase caused by adhesive deterioration.

Abstract: To provide an optical connector that can prevent degradation of end faces of cores using a simple structure. The optical connector is adapted to connect single-mode optical fibers for visible light with a wavelength of less than or equal to 650 nm to ultraviolet light, specifically, connect the optical fibers by allowing ferrules having fixed thereto the respective optical fibers to be inserted into a sleeve and allowing the ferrules to butt against each other, in which a film of nitride, oxide, or fluoride is formed on an end face of each of the optical fibers and the ferrules.

Abstract: A dependency of a characteristic of an optical circuit on an optical signal intensity occurring due to input of a high intensity optical signal is reduced in a waveguide type optical interferometer circuit. The waveguide type optical interferometer circuit is a waveguide type optical interferometer circuit formed in one plane, and includes an input waveguide, an optical branching unit, an optical coupling unit, an output waveguide, and optical waveguides having different lengths from each other and being interposed between the optical branching unit and the optical coupling unit. A light intensity compensating region is formed on an optical path extending from the optical branching unit to the optical coupling unit, and the light intensity compensating region is formed by using a light intensity compensating material having a light intensity coefficient different from a light intensity coefficient of an optical distance relative to an incident light intensity in the optical path.

Abstract: There is provided a respiration estimation method. The respiration estimation method includes a first step (S107) of estimating a breathing rate of a subject based on each of a time-series signal of first data relating to a cardiac function of the subject and a time-series signal of second data relating to an acceleration by a respiratory motion of the subject, a second step (S108) of estimating a breathing rate obtained by filtering noise using a Kalman filter for each of the breathing rate estimated based on the first data and the breathing rate estimated based on the second data, and a third step (S109) of executing weighted averaging processing for the plurality of estimated values of the breathing rates obtained in the second step.