Abstract: A fiber-optic communication apparatus includes an optical monitor that monitors a WDM signal in which optical signals of multiple channels are multiplexed, a processor that calculates a control value for controlling an optical power of the WDM signal, based on a power spectrum detected by the optical monitor, in a unit interval of frequency narrower than a channel bandwidth of the WDM signal, and an optical power adjusting mechanism that adjusts the optical power of the WDM signal in the unit interval of frequency based on the control value.

Abstract: A coherent transceiver includes a modulator, a receiver, a filter, a splitter, a detector, and a controller. The modulator modulates a data on the basis of laser light and outputs transmission light. The receiver receives reception light with same wavelength as the transmission light from input multiplexed light, on the basis of the laser light. The filter is arranged on an input stage of the receiver and includes a first port that inputs the multiplexed light, a filter body that transmits the reception light from the multiplexed light, and a second port that outputs the transmitted reception light. The splitter splits the transmission light travelling from the modulator and inputs the splitted transmission light. The detector detects a level of the splitted transmission light input. The controller adjusts a passband of the filter on the basis of the detected level.

Abstract: An optical amplification apparatus includes: a light source that outputs to an optical transmission path first pump light which Raman amplifies signal light input from the optical transmission path and which is of a first wavelength band; a first detector that detects input, from the optical transmission path, of second pump light of a second wavelength band which is different from the first wavelength band; and a processor that performs safety light control on the light source in a case where the input of the second pump light is not detected.

Abstract: A coherent transceiver includes a modulator, a receiver, a filter, a splitter, a detector, and a controller. The modulator modulates a data on the basis of laser light and outputs transmission light. The receiver receives reception light with same wavelength as the transmission light from input multiplexed light, on the basis of the laser light. The filter is arranged on an input stage of the receiver and includes a first port that inputs the multiplexed light, a filter body that transmits the reception light from the multiplexed light, and a second port that outputs the transmitted reception light. The splitter splits the transmission light travelling from the modulator and inputs the splitted transmission light. The detector detects a level of the splitted transmission light input. The controller adjusts a passband of the filter on the basis of the detected level.

Abstract: A controller for a front-exciting Raman-amplifier that amplifies an optical signal transmitted from one end of an optical fiber to other end by inputting an excitation light to the one end, the controller includes a memory, and a processor coupled to the memory and configured to acquire communication-related information regarding communication of the optical signal in the optical fiber, when the acquired communication-related information does not indicate the communication of the optical signal, set a Raman gain of the front-exciting Raman amplifier based on a first light intensity of an amplified spontaneous scattered light of the excitation light, and when the acquired communication-related information indicates the communication of the optical signal, set the Raman gain based on a second light intensity of the optical signal output from the optical fiber.

Abstract: A fiber-optic communication apparatus includes an optical monitor that monitors a WDM signal in. which optical signals of multiple channels are multiplexed, a processor that calculates a control value for controlling an optical power of the WDM signal, based. on a power spectrum detected by the optical monitor, in a unit interval of frequency narrower than a channel bandwidth of the WDM signal, and an optical power adjusting mechanism that adjusts the optical power of the WDM signal in the unit interval of frequency based on the control value.

Abstract: A controller for a front-exciting Raman-amplifier that amplifies an optical signal transmitted from one end of an optical fiber to other end by inputting an excitation light to the one end, the controller includes a memory, and a processor coupled to the memory and configured to acquire communication-related information regarding communication of the optical signal in the optical fiber, when the acquired communication-related information does not indicate the communication of the optical signal, set a Raman gain of the front-exciting Raman amplifier based on a first light intensity of an amplified spontaneous scattered light of the excitation light, and when the acquired communication-related information indicates the communication of the optical signal, set the Raman gain based on a second light intensity of the optical signal output from the optical fiber.

Abstract: A transmission device includes a transmitter configured to output first monitoring signal light regarding monitoring control of the transmission device; and a switch that switches an output destination of the first monitoring signal light output from the transmitter to any one of a first transmission path or a second transmission path, wherein in the first transmission path, a first main signal is transmitted from the transmission device to another transmission device, and in the second transmission path, a second main signal is transmitted from the other transmission device to the transmission device.

Abstract: A transmission device that transmits main signal light to another transmission device via a transmission path, the transmission device includes a transmitter that generates monitoring signal light with intensity modulation based on a signal related to monitoring control of the transmission device and the other transmission device, a multiplexer that multiplexes the monitoring signal light into the main signal light, a receiver that acquires light receiving information from the other transmission device, the light receiving information being related to a light receiving state of the monitoring signal light, and a control circuit that controls a modulation degree of the intensity modulation in accordance with the light receiving information.

Abstract: A transmission device that transmits main signal light to another transmission device via a transmission path, the transmission device includes a transmitter that generates monitoring signal light with intensity modulation based on a signal related to monitoring control of the transmission device and the other transmission device, a multiplexer that multiplexes the monitoring signal light into the main signal light, a receiver that acquires light receiving information from the other transmission device, the light receiving information being related to a light receiving state of the monitoring signal light, and a control circuit that controls a modulation degree of the intensity modulation in accordance with the light receiving information.

Abstract: A transmission device includes a transmitter configured to output first monitoring signal light regarding monitoring control of the transmission device; and a switch that switches an output destination of the first monitoring signal light output from the transmitter to any one of a first transmission path or a second transmission path, wherein in the first transmission path, a first main signal is transmitted from the transmission device to another transmission device, and in the second transmission path, a second main signal is transmitted from the other transmission device to the transmission device.

Abstract: A converter includes a combiner configured to polarization-combine a first pump light and a second pump light, a nonlinear medium configured to wavelength-convert first signal light into second signal light to output the second signal light after wavelength conversion from a second port, and to wavelength-convert the second signal light into first signal light to output the first signal light after wavelength conversion from the first port, a first circulator configured to input the first signal light from the first port into the nonlinear medium, and output the first signal light after wavelength conversion in the nonlinear medium from the first port, and a second circulator configured to input the second signal light from the second port into the nonlinear medium, and output the second signal light after wavelength conversion in the nonlinear medium from the second port.

Abstract: An optical transmission apparatus includes a splitter configured to split a first wavelength division multiplexed optical signal arranged in a first wavelength band and a second wavelength division multiplexed optical signal arranged in a second wavelength band, respectively, from an optical signal including the first wavelength division multiplexed optical signal and the second wavelength division multiplexed optical signal, a wavelength converter configured to convert a wavelength of the split second wavelength division multiplexed optical signal to generate a third wavelength division multiplexed optical signal to be arranged in the first wavelength band, an optical monitor configured to monitor power of each wavelength channel of the third wavelength division multiplexed optical signal, and a transmitter configured to transmit a monitoring result by the optical monitor to a transmission source node of the optical signal or a relay node of the optical signal.

Abstract: A converter includes a combiner configured to polarization-combine a first pump light and a second pump light, a nonlinear medium configured to wavelength-convert first signal light into second signal light to output the second signal light after wavelength conversion from a second port, and to wavelength-convert the second signal light into first signal light to output the first signal light after wavelength conversion from the first port, a first circulator configured to input the first signal light from the first port into the nonlinear medium, and output the first signal light after wavelength conversion in the nonlinear medium from the first port, and a second circulator configured to input the second signal light from the second port into the nonlinear medium, and output the second signal light after wavelength conversion in the nonlinear medium from the second port.

Abstract: An optical transmission apparatus includes a splitter configured to split a first wavelength division multiplexed optical signal arranged in a first wavelength band and a second wavelength division multiplexed optical signal arranged in a second wavelength band, respectively, from an optical signal including the first wavelength division multiplexed optical signal and the second wavelength division multiplexed optical signal, a wavelength converter configured to convert a wavelength of the split second wavelength division multiplexed optical signal to generate a third wavelength division multiplexed optical signal to be arranged in the first wavelength band, an optical monitor configured to monitor power of each wavelength channel of the third wavelength division multiplexed optical signal, and a transmitter configured to transmit a monitoring result by the optical monitor to a transmission source node of the optical signal or a relay node of the optical signal.

Abstract: An optical transmission apparatus includes an amplifier array device; and a switch device coupled to the amplifier array device via an optical cable, wherein the amplifier array device includes a plurality of amplifiers configured to amplify a plurality of optical signals at mutually different wavelengths and to output the plurality of amplified optical signals, a plurality of beam separators configured to generate a plurality of separated light beams by separating the plurality of amplified optical signals and to output the plurality of separated light beams, a beam combiner configured to generate combined light by combining the plurality of separated light beams and to output the combined light to the switch device through the optical cable, and a photo-detector configured to detect a power of the combined light returned from the switch device through the optical cable.

Abstract: A switchable optical amplifier includes: a first optical amplifier; a second optical amplifier; and an optical switch which includes first and second input ports and first and second output ports, the optical switch that switches between a first connection state where the first input port and the first output port are in an optical connection and the second input port and the second output port are in a no optical connection and a second connection state where the first input port and the second output port are in an optical connection and the second input port and the first output port are in an optical connection, wherein an output of the first optical amplifier is optically coupled to the first input port of the optical switch, an input of the second optical amplifier is optically coupled to the second output port of the optical switch.

Abstract: An optical transmission device includes a receiver that receives first light, a transmitter that outputs second light, a memory, a processor coupled to the memory, configured to control a first optical level of the second light in such a way that a second optical level calculated based on an optical level of the received first light and an optical level of the second light that is output from the transmitter becomes a predetermined target value, a combiner that combines the received first light and the second light for which the first optical level is controlled by the processor, and an amplifier that amplifies the combined light.

Abstract: An optical amplifier includes an optical amplifying unit, a splitting unit, and a loss adjusting unit. The optical amplifying unit provides gain to wavelength multiplexed light received from a transmission line, to amplify light intensity. The splitting unit splits the amplified wavelength multiplexed light. The loss adjusting unit adjusts loss provided to each wavelength of a first portion of the split wavelength multiplexed light based on the gain.

Abstract: An optical transmission apparatus includes an amplifier array device; and a switch device coupled to the amplifier array device via an optical cable, wherein the amplifier array device includes a plurality of amplifiers configured to amplify a plurality of optical signals at mutually different wavelengths and to output the plurality of amplified optical signals, a plurality of beam separators configured to generate a plurality of separated light beams by separating the plurality of amplified optical signals and to output the plurality of separated light beams, a beam combiner configured to generate combined light by combining the plurality of separated light beams and to output the combined light to the switch device through the optical cable, and a photo-detector configured to detect a power of the combined light returned from the switch device through the optical cable.