Abstract: An object of the present disclosure is to provide a power coupling coefficient measurement method and a power coupling coefficient measurement device capable of inexpensively and easily measuring a power coupling coefficient. The power coupling coefficient measurement method according to the present disclosure is a power coupling coefficient measurement method for measuring a power coupling coefficient of a multi-core fiber in order to achieve the aforementioned object, and includes: inputting a test light pulse from one end of the multi-core fiber to any one of cores; receiving backscattered light of the core to which the test light pulse is input or any one of the other cores; measuring an intensity distribution of the backscattered light with respect to a distance from the one end of the multi-core fiber; and calculating the power coupling coefficient from the intensity distribution of the backscattered light.

Abstract: A phase measurement method is presented which causes wavelength-multiplexed pulsed light to be incident on a measurement target optical fiber, produces a scattered light vector obtained by plotting scattered light from the measurement target optical fiber for each wavelength onto a two-dimensional plane having the in-phase component thereof on the horizontal axis and the orthogonal component thereof on the vertical axis, rotates the produced scattered light vector for each wavelength at each place in the measurement target optical fiber to align the directions of the vectors, generates a new vector by calculating the arithmetic average of the vectors having the aligned directions, and calculates the phase by using the values of the in-phase and orthogonal components of the generated new vector.

Abstract: A red-light emitting diode, LED, includes an active layer configured to generate red light, the active layer having first and second faces that are opposite to each other, a first barrier layer located on the first face of the active layer, a second barrier layer located on the second face of the active layer, a hole blocking layer located on the first barrier layer, opposite to the active layer, the hole blocking layer being configured to prevent holes to escape from the active layer, a first electrode located on the second barrier layer, and a second electrode located on the hole blocking layer. A bandgap of the hole blocking layer is larger than a bandgap of the first barrier layer.

Abstract: An object of the present disclosure is to provide a few-mode fiber testing method and a few-mode fiber testing device capable of acquiring a loss and inter-mode crosstalk for each mode at a connection point of a few-mode fiber by measurement only from one end of FUT.

Abstract: An optical fiber measurement system is presented. The optical fiber measurement system includes a light incident circuit which makes a probe light incident on one end of an optical fiber and makes a secondary probe light and a pump light as an optical pulse incident on the other end of the optical fiber; a light receiver which measures a light intensity of arbitrary one propagation mode in the probe light propagating through the optical fiber; and a control calculation device which sets a propagation mode of the probe light, the secondary probe light, and the pump light, an optical frequency difference of the secondary probe light, and an optical frequency difference of the pump light with respect to the light incident circuit, and calculates loss and crosstalk at each point in a longitudinal direction of the optical fiber from the light intensity measured by the light receiver.

Abstract: An object of the present invention is to propose a design method of a minimum value N of the number of multiplexed frequencies that is necessary for measuring an object vibrational frequency according to DAS-P while taking into consideration a trade-off between a measurement distance and an upper limit of a measurable vibrational frequency. When a phase change of an arbitrary section of a measured optical fiber is represented by A×sin(2?fvt), N=4Zfv/? is satisfied when A is smaller than ?/2 but N=2Zfv/(?·Arcsin (?/2A)) is satisfied when A is equal to or larger than ?/2, where fv represents vibrational frequency, t represents time, Z represents a length of the measured optical fiber (a measurement distance), and ? represents the speed of light inside the measured optical fiber.

Abstract: In order to achieve the above object, a signal processing method according to the present disclosure includes: a calculation step of calculating a phase change at each of points on a medium from a phase of a reflected signal generated by a pulse signal transmitted to the medium, at each of predetermined times; a phase connection step of performing phase connection processing, at each of the predetermined times, on the phase change at each of the points calculated in the calculation step; and a correction step of detecting an outlier using a phase change at each of the points at the same time at which the phase connection processing is performed in the phase connection step, and correcting the outlier, at each of the predetermined times.

Abstract: The present disclosure generates an optical spectrogram, representing a temporal change in frequency characteristics, using a plurality of spectral data measured by an OFDR measurement instrument at different times, and filters the optical spectrogram in both a time direction and a frequency direction.

Abstract: The present disclosure relates to a signal processing device that: acquires a signal obtained by repeatedly injecting a plurality of light pulses with different optical frequencies into an optical fiber, and by performing distributed acoustic sensing-phase (DAS-P); calculates a phase change, caused by vibration applied to a section of the optical fiber, using the acquired signal; removes, from the calculated phase change, a component regarding a repetition period of the same optical frequency of the plurality of light pulses; and calculates the vibration applied to the section of the optical fiber, using a phase change obtained by removing the component regarding the period.

Abstract: The present disclosure provides an underground facility position contrast system S, which includes: a scattered light intensity distribution measurement device 1 for measuring, when an earthquake vibration is applied to an optical fiber F laid underground, a change over time in a scattered light intensity distribution in a longitudinal direction of the optical fiber F; and an underground facility position contrast device 2 for measuring a change over time in a distortion response distribution in the longitudinal direction of the optical fiber F based on the change over time in the scattered light intensity distribution in the longitudinal direction of the optical fiber F, estimating an underground facility state of the optical fiber F based on the change over time in the distortion response distribution in the longitudinal direction of the optical fiber F, and associating the underground facility position of the optical fiber F with a longitudinal distance of the optical fiber F.

Abstract: Objects of the present invention are to provide a snow accumulation estimating system and a method for estimating a snow accumulation which enable a snow accumulation to be remotely measured accurately and economically. A snow accumulation estimating system 301 according to the present invention includes: an optical fiber 50 that receives vibration from a random point on snow; a vibration measuring instrument 11 that measures the vibration received by the optical fiber 50 as a distribution in a longitudinal direction of the optical fiber 50; and an analysis processing unit 12 that has, as accumulated data, a relationship between a snow accumulation and the vibration received by the optical fiber 50, compares the distribution measured as measurement data by the vibration measuring instrument 11 with the accumulated data, and estimates a snow accumulation at the random point.

Abstract: An optical semiconductor element includes a substrate and a plurality of cells. Each cell includes an optical layer, a first semiconductor layer, and a second semiconductor layer. The plurality of cells include a first cell and a second cell. The second semiconductor layer of the first cell and the first semiconductor layer of the second cell are electrically connected to each other by a first connection portion of a first wiring portion. The first wiring portion has a first extending portion that extends from the first connection portion so as to surround four side portions of the optical layer of the first cell. The optical layer is an active layer that generates light having a central wavelength of 3 ?m or more and 10 ?m or less or an absorption layer having a maximum sensitivity wavelength of 3 ?m or more and 10 ?m or less.

Abstract: The present disclosure aims to reduce a strain of an observed waveform caused by a difference in proportional constant between responses of different optical frequencies of probe light resulting from vibration in a phase OTDR that uses different optical frequencies.

Abstract: An optical semiconductor element includes: a substrate; and a plurality of cells formed on the substrate, the plurality of cells including a first cell, a second cell, and a third cell. A first electrode electrically connected to a first semiconductor layer of the first cell is arranged on the top surface of the first cell, and a second electrode electrically connected to a second semiconductor layer of the third cell is arranged on the top surface of the second cell. Each of the first electrode and the second electrode has a planned contact region with which solder comes into contact during electrical connection with an external member. When viewed from the thickness direction of the substrate, the area of the second electrode on the top surface of the second cell is smaller than the area of the first electrode on the top surface of the first cell.

Abstract: Provided is a honeycomb-type ceramic positive electrode having a columnar honeycomb structure, having a first end face, a second end face parallel to the first end face, and an outer side face perpendicular to the first end face and the second end face, and also having a plurality of holes extending from the first end face to the second end face. The honeycomb-type ceramic positive electrode is composed of a lithium complex oxide sintered body in which a plurality of primary grains composed of a lithium complex oxide are bonded, and when a central axis of the columnar honeycomb structure parallel to the outer side face or an axis parallel thereto is defined as a z-axis, the plurality of primary grains are oriented in a z-axis direction.

Abstract: Provided is a lithium secondary battery, including: a positive electrode layer including a lithium composite oxide sintered body; a negative electrode layer; a separator interposed between the positive electrode layer and the negative electrode layer; an electrolytic solution impregnated into the positive electrode layer, the negative electrode layer, and the separator; and an exterior body, which has a closed space and is configured to store the positive electrode layer, the negative electrode layer, the separator, and the electrolytic solution in the closed space. This lithium secondary battery has a determination coefficient R2 of 0.8 or more, which is obtained when plots of a square root of the number of days elapsed of up to 180 days and a capacity maintenance ratio (%) in a float charging test are linearly regressed.

Abstract: A reuse support system performs an electrode degradation judgment to judge, based on one or a plurality of kinds of first data diagnosed regarding a ceramic electrode removed from a lithium-ion secondary battery having the ceramic electrode, whether or not a degradation degree of the removed ceramic electrode satisfies a condition for enabling regeneration of the ceramic electrode.

Abstract: A signal processing method executed by a signal processing device, includes performing a phase connection process on a position in a space and a phase value at each of a plurality of times, performing outlier correction of a phase value for each position in the space in a predetermined direction of the space at a predetermined time among the plurality of times based on a result of the phase connection process, and correcting a phase value at a time other than the predetermined time for each of correction target positions among positions in the space.

Abstract: The present disclosure relates to a vibration measuring instrument that repeatedly injects a plurality of light pulses with different optical frequencies into an optical fiber, and performs distributed acoustic sensing-phase (DAS-P). In the vibration measuring instrument, light pulses having a waveform with a spectral side lobe smaller than a side lobe of a rectangular wave are used as the plurality of light pulses.

Abstract: An object of the present invention is to provide a sensing system, a sensing method, and an analyzing device using OFDR in which a sensing range of strain/temperature is less likely to be limited by a frequency sweep width. In the sensing method using OFDR, the sensing system according to the present invention employs sequential update, per measurement by one frequency sweep of the probe light, for setting the reference spectrum to the spectrum of an immediately preceding measurement, by which a spectral shift between an n-th measurement and an (n?1)th measurement is obtained, and the spectral shifts individually obtained between the measurements are integrated.