Abstract: A communication device includes: a MAC unit that processes a main signal including a payload, and determines a communication timing of the main signal; a communication unit that performs, based on the communication timing, at least one of transmission processing for E/O converting the main signal acquired from the MAC unit, and transmitting the main signal to a communication counterpart device, and reception processing for O/E converting the main signal received from the communication counterpart device; a main signal transmission line through which the main signal is transmitted between the MAC unit and the communication unit; and a control information transmission line that is provided separately from the main signal transmission line, and through which communication timing data that is data indicating the communication timing is transmitted from the MAC unit to the communication unit.

Abstract: In general, according to an embodiment, a memory system includes a memory device including a memory cell; and a controller. The controller is configured to: receive first data from the memory cell in a first data reading; receive second data from the memory cell in a second data reading that is different from the first data reading; convert a first value that is based on the first data and the second data, to a second value in accordance with a first relationship; and convert the first value to a third value in accordance with a second relationship that is different from the first relationship.

Abstract: A coherent optical reception device includes a coherent receiver that receives signal light in which an AMCC signal is superimposed on a main signal by phase modulation and outputs a reception signal and a digital signal processor, in which a modulation signal of the AMCC signal superimposed on the main signal is multiplied by a clock, the digital signal processor includes a symbol output, an AMCC signal code sequence demodulator, and a main signal code sequence demodulator, and the AMCC signal code sequence demodulator includes a main signal component remover that removes the main signal included in the reception signal output from the symbol output, and a clock component remover that removes a clock component included in the reception signal from which the main signal has been removed by the main signal component remover.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes first to fourth word lines and first to fourth memory cells. The controller is configured to issue first and second instructions. The controller is further configured to execute a first operation to obtain a first read voltage based on a threshold distribution of the first memory cell, and a second operation to read data from the second memory cell.

Abstract: An optical reception device including: a local light transmission unit configured to generate a plurality of local lights having different wavelengths, select a local light having a wavelength that is close to the wavelength of a received optical signal from among the plurality of generated local lights having different wavelengths, and transmit the selected local light to a coherent receiver; a demultiplexing unit configured to demultiplex a received optical signal and transmit the demultiplexed optical signal to the coherent receiver via a first path; and a wavelength detection unit configured to input the optical signal demultiplexed by the demultiplexing unit via a second path, split the input optical signal into different paths according to wavelengths by using a wavelength multiplexer/demultiplexer, and output, to the local light transmission unit, a control signal for causing the local light transmission unit to output a local light having a frequency that corresponds to a path in which the optical sig

Abstract: An optical communication system configured with a station-side apparatus and a plurality of subscriber-side apparatuses in a bus network topology includes an optical amplification unit installed on a station side, and a drop unit configured to branch an optical signal and excitation light, wherein the optical amplification unit includes an amplifier configured to amplify a downlink signal, and an excitation light output unit configured to output the excitation light for amplifying an uplink signal to a communication path, and the drop unit changes a branching ratio in accordance with a wavelength of the optical signal so that a transmission loss of the excitation light with respect to a trunk fiber is reduced.

Abstract: A coherent optical reception device includes a coherent receiver that receives signal light in which an AMCC signal is superimposed on a main signal, converts the signal light into an analog electric signal, and outputs an in-phase component and a quadrature-phase component of a reception signal for each polarization state, and a polarization combiner that performs polarization combining on the in-phase component and the quadrature-phase component of the reception signal output from the coherent receiver for each polarization state and outputs the reception signal as an AMCC signal identification reception signal that is the reception signal used for identification of the AMCC signal and a main signal identification reception signal that is the reception signal used for identification of the main signal.

Abstract: An optical transmission apparatus includes an optical transmitter that generates an optical signal in an uplink direction by modulating output light of a laser that outputs light of a first frequency with a subcarrier on which transmission data is superimposed, a heterodyne detection unit that receives an optical signal in a downlink direction by heterodyne detection, a control unit that calculates a first intermediate frequency based on the frequency of the downlink signal received by the heterodyne detection and the first frequency of the laser, and controls the first frequency of the laser when there is a difference between the calculated first intermediate frequency and a reference second intermediate frequency by a threshold or more.

Abstract: An optical transmitting device includes a plurality of optical transmitting units that output optical signals with different wavelengths, a multiplexer that wavelength-multiplexes the plurality of the optical signals output from the plurality of optical transmitting units, and an amplifying unit that amplifies the wavelength-multiplexed optical signal, in which the plurality of optical transmitting units include a monitoring control signal application unit that adds a monitoring control signal to a constant current for driving a laser to generate a driving signal and applies the driving signal to the laser, a laser that outputs an optical signal in accordance with the driving signal applied to the monitoring control signal application unit, and a modulator that modulates the optical signal output from the laser with a main signal.

Abstract: There is provided an optical power feeding system including: an optical power feeding unit; and a plurality of drop units configured to be able to receive light from the optical power feeding unit as an input, branch the input light, and output branched light, in which, the optical power feeding unit includes a power-feed light generating unit that outputs power-feed light, and the drop unit includes: an optical splitter that branches the power-feed light into first branch light and second branch light and outputs the second branch light to another drop unit; a photoelectric conversion unit that performs photoelectric conversion of the first branch light; and a branch ratio control unit that is driven by electricity generated by the photoelectric conversion and controls a branch ratio that is a ratio between the first branch light and the second branch light.

Abstract: An optical access system includes an optical transmission device and an optical reception device. In the optical access system, the optical transmission device includes: a signal generation unit that generates a plurality of optical signals by generating monitoring control signals including identical information in predetermined cycles and superimposing the monitoring control signal on a main signal each time generating the monitoring control signal; and a transmission unit that transmits the generated optical signals to the optical reception device.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes first to fourth word lines and first to fourth memory cells. The controller is configured to issue first and second instructions. The controller is further configured to execute a first operation to obtain a first read voltage based on a threshold distribution of the first memory cell, and a second operation to read data from the second memory cell.

Abstract: A branch ratio setting system includes: a branch ratio control unit; and a plurality of drop units configured to be able to receive an optical signal from the branch ratio control unit, and configured to branch and output the received optical signal, and the branch ratio control unit outputs light to the plurality of drop units via an optical fiber to measure characteristics of the optical fiber, and outputs a branch ratio determination signal to each of the plurality of drop units via the optical fiber based on the measured characteristics of the optical fiber, and the drop unit includes an optical splitter connected to the optical fiber and having a variable branch ratio and a branch ratio setting unit that sets the branch ratio of the optical splitter based on the branch ratio determination signal input via the optical fiber.

Abstract: A branch ratio calculation method in an optical communication system constituting a tree-structured network in which a first communication device is used as a root node, a plurality of optical splitters are used as intermediate nodes, and a plurality of second communication devices are used as leaf nodes, the method including a calculation step of calculating branch ratios of the plurality of optical splitters based on a length of a transmission path between the first communication device and the optical fiber in order from a hierarchy of the tree-structured network so that the second communication device receives light transmitted by the first communication device at a target intensity.

Abstract: A communication device includes: a MAC unit that processes a main signal including a payload, and determines a communication timing of the main signal; a communication unit that performs, based on the communication timing, at least one of transmission processing for E/O converting the main signal acquired from the MAC unit, and transmitting the main signal to a communication counterpart device, and reception processing for O/E converting the main signal received from the communication counterpart device; a main signal transmission line through which the main signal is transmitted between the MAC unit and the communication unit; and a control information transmission line that is provided separately from the main signal transmission line, and through which communication timing data that is data indicating the communication timing is transmitted from the MAC unit to the communication unit.

Abstract: An optical amplification estimation method includes by an excitation light output unit connected to a first end of a first optical transmission line, making excitation light incident on the first optical transmission line, by a monitoring unit connected to the same side as the first end of the first optical transmission line, making monitoring light incident on the first optical transmission line, the monitoring light having a wavelength different from a wavelength of the excitation light, by the monitoring unit, measuring intensity of light incident on the monitoring unit when the excitation light is incident, and intensity of light incident on the monitoring unit when the excitation light is not incident, and by an amplification estimation unit, estimating a gain of an optical signal in the first optical transmission line based on the light intensity measured in the measuring.

Abstract: Provided is an optical receiver including: a heterodyne detection unit that converts, by heterodyne detection, a subcarrier multiplexed signal in which a plurality of optical signals transmitted from a plurality of optical transmitters are multiplexed, into an electrical signal in an intermediate frequency band; a filter unit that removes a carrier component from the electrical signal in the intermediate frequency band, generated by the conversion, to extract a subcarrier component; an analog-digital conversion unit that performs analog-digital conversion on a signal having the subcarrier component, extracted by the filter unit; and a digital signal processing unit that performs digital signal processing for each subcarrier on a digital signal generated by the analog-digital conversion performed by the analog-digital conversion unit.

Abstract: A light leakage confirmation method comprising: an excitation light incident step in which an excitation light output unit connected to a first end of a first optical transmission line outputs an excitation light and makes the excitation light incident on the first optical transmission line; a reflection step in which an excitation light reflection unit connected to a second end of the first optical transmission line reflects the excitation light which has been incident in the excitation light incident step; a reflected light incident step of making a reflected light which has been reflected in the reflection step incident on the first optical transmission line; a reflected light measurement step in which the excitation light output unit measures an intensity of the reflected light; and a leakage determination step of determining whether or not the excitation light is leaked on a basis of the intensity of the excitation light and the intensity of the reflected light which has been measured in the reflected li

Abstract: An optical reception device including: a wavelength selection unit configured to split an optical signal amplified by an optical amplifier into different paths according to wavelengths by using a wavelength multiplexer/demultiplexer, and control a passage state of a passage target optical switch through which the optical signal is to be passed, out of a plurality of optical switches provided on the respective paths, to select an optical signal of a path where the optical signal entered and output the optical signal to a receiver; and a wavelength detection unit configured to detect the wavelength of an optical signal by using each of a plurality of optical detectors, determine the passage target optical switch based on a detection result, and output, to the determined passage target optical switch, a control signal for controlling the passage target optical switch so as to enter the passage state, the optical detectors being respectively provided on different paths that are different from the paths on which t

Abstract: An optical communication system having an optical transmission line, where a first section of the optical transmission line is connected to a first optical communication device; and a second section of the optical transmission line is connected to a second optical communication device. The optical communication system further includes: a Raman light source; an incident device connected to same end of the second section of the optical transmission line as the second optical communication device; and a separating device interconnecting the first section of the optical transmission line to the second section of the optical transmission line. The incident device causes excitation light output from the Raman light source to be incident to the second section of the optical transmission line and performs distributed Raman amplification on the optical signal; and the separating device separates the excitation light that is caused to be incident by the incident device.