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: A transmission device that transmits wavelength multiplexed light to a transmission line, the transmission device includes a first multiplexer configured to multiplex light of a wavelength of a first wavelength band and output first multiplexed light, a second multiplexer configured to multiplex the light of the wavelength of the first wavelength band and output second multiplexed light, a wavelength converter configured to convert the second multiplexed light into light of a wavelength of a second wavelength band different from the first wavelength band, and a third multiplexer configured to multiplex the second multiplexed light converted to the light of the wavelength of the second wavelength band and the first multiplexed light and output the wavelength multiplexed light.

Abstract: An optical transfer method of an optical transfer system including a transmitter, a first wavelength converter configured to use first excitation light to perform wavelength-conversion of first signal light which is the transmission light into second signal light in a different wavelength band, a second wavelength converter configured to use second excitation light to perform wavelength-conversion of the second signal light into third signal light in a different wavelength band, and a receiver configured to receive the third signal light, the method includes acquiring a wavelength of the transmission light, a wavelength of the first excitation light, and a wavelength of the second excitation light; and deciding local emission light of the receiver based on a wavelength of reception light of the receiver obtained from the wavelength of the transmission light, the wavelength of the first excitation light, and the wavelength of the second excitation light.

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: A wavelength conversion device includes a light source configured to output an excitation light beam, a modulator configured to phase-modulate the excitation light beam, a polarization adjustor configured to adjust a polarization angle of the excitation light beam to 45 degrees or 135 degrees with respect to a polarization angle of a signal light beam, and a nonlinear medium configured to generate four-wave mixing of the excitation light beam whose polarization angle is adjusted and the signal light beam to generate an idler light beam having a frequency corresponding to a difference between frequencies of the signal light beam and the excitation light beam from the signal light beam.

Abstract: A wavelength conversion apparatus includes a multiplexer-demultiplexer configured to include a first port, a second port, and a third port, a looped non-linear optical medium including one end that is optically connected to the second port of the multiplexer-demultiplexer, another end that is optically connected to the third port of the multiplexer-demultiplexer, and a main axis that rotates by 90 degrees between the second port and the third port, a first filter configured to be inserted into the non-linear optical medium, and remove stimulated Brillouin backscattered light that is bidirectionally generated in the non-linear optical medium, and a second filter configured to take out, from output light that is multiplexed in the multiplexer-demultiplexer after propagating through the non-linear optical medium and is outputted from the first port, conversion light having a third frequency different from the frequencies of a signal light and an excitation light.

Abstract: A transmission apparatus includes a first multiplexer configured to multiplex light of wavelengths of a first wavelength band to output first wavelength multiplex light, a first wavelength converter configured to convert the first wavelength multiplex light into wavelengths of a second wavelength band which is different from the first wavelength band, by using first excitation light, a second multiplexer configured to multiplex light of wavelengths of the first wavelength band which are different from the wavelengths of the first wavelength multiplex light to output second wavelength multiplex light, a second wavelength converter configured to convert the second wavelength multiplex light into wavelengths of the second wavelength band, by using second excitation light, a third multiplexer configured to multiplex the first wavelength multiplex light converted into the wavelengths of the second wavelength band, and the second wavelength multiplex light converted into the wavelengths of the second wavelength ban

Abstract: An optical transmission apparatus includes a first transmitter configured to output an optical signal having a wavelength belonging to a first wavelength band, a switch configured to output the optical signal outputted to the first transmitter toward a first transmission line or a second transmission line, a wavelength converter configured to convert the optical signal outputted from the switch toward the first transmission line into an optical signal having a wavelength belonging to a second wavelength band other than the first wavelength band, a second transmitter configured to output an optical signal having a wavelength belonging to the first wavelength band, and a first multiplexer configured to multiplex the optical signal outputted from the first wavelength converter and the optical signal outputted from the second transmitter, and output a multiplexed optical signal to the first transmission line.

Abstract: There is provided an optical transmission control device includes a memory, and a processor coupled to the memory and the processor configured to aggregate information of candidacy sections having a possibility that communication is discontinued among wavelength-multiplexed transmission sections, classify, based on the aggregated information, optical paths set between optical transmission devices into a first optical path on which, when communication in the candidacy sections is discontinued, an optical signal is not transmitted, and a second optical path on which, when the communication in the candidacy sections is discontinued, an optical signal is transmitted, and determine a wavelength allocation in a first wavelength group of the first optical path and a second wavelength group of the second optical path so that a difference in gain wavelength characteristics of the first optical path and the second optical path is equal to or less than a predetermined level.

Abstract: An optical amplifier includes: an amplification section includes a plurality of routes; a determination section that selects a passage route, through which the multi-wavelength optical signal passes, among the plurality of routes; an input-side detector that detects input power of the multi-wavelength optical signal input to the amplification section; a variable optical attenuator that attenuates the multi-wavelength optical signal that is amplified through passing through the passage route determined by the determination section; an output-side detector that detects output power of the multi-wavelength optical signal attenuated by the variable optical attenuator; a controller that controls the amplification section based on the input power detected by the input-side detector and the output power detected by the output-side detector such that a gain of the amplification section is steady; and an adjuster that adjusts an attenuation of the variable optical attenuator in accordance with the input power detected

Abstract: There is provided an optical transmission control device includes a memory, and a processor coupled to the memory and the processor configured to aggregate information of candidacy sections having a possibility that communication is discontinued among wavelength-multiplexed transmission sections, classify, based on the aggregated information, optical paths set between optical transmission devices into a first optical path on which, when communication in the candidacy sections is discontinued, an optical signal is not transmitted, and a second optical path on which, when the communication in the candidacy sections is discontinued, an optical signal is transmitted, and determine a wavelength allocation in a first wavelength group of the first optical path and a second wavelength group of the second optical path so that a difference in gain wavelength characteristics of the first optical path and the second optical path is equal to or less than a predetermined level.

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 system includes: a first optical transmission device configured to perform bidirectional optical transmission with a second optical transmission device via an optical transmission line, wherein the first optical transmission device includes a transmitted light power adjusting section configured to transmit, to the second optical transmission device, a first light power which is set based on a measurement result, the second transmission device measuring a fluctuating light power transmitted from the first transmission device and informing the first transmission device of the measurement result.

Abstract: An optical amplifier includes: an amplification section includes a plurality of routes; a determination section that selects a passage route, through which the multi-wavelength optical signal passes, among the plurality of routes; an input-side detector that detects input power of the multi-wavelength optical signal input to the amplification section; a variable optical attenuator that attenuates the multi-wavelength optical signal that is amplified through passing through the passage route determined by the determination section; an output-side detector that detects output power of the multi-wavelength optical signal attenuated by the variable optical attenuator; a controller that controls the amplification section based on the input power detected by the input-side detector and the output power detected by the output-side detector such that a gain of the amplification section is steady; and an adjuster that adjusts an attenuation of the variable optical attenuator in accordance with the input power detected

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 or the split wavelength multiplexed light based on the gain.

Abstract: An amplifying-apparatus that raman-amplifies light transmitted through an optical-fiber-transmission-path, includes: an inputting-unit that inputs pump light to the optical-fiber-transmission-path; a path-switching-unit that is capable of switching between a first state in which the light transmitted through the optical-fiber-transmission-path is output to a first path and a second state in which the light transmitted through the optical-fiber-transmission-path is output to a second path; a splitting-unit that splits the light output to the second path by the path-switching-unit and outputs resulting first light and second light; and a control-circuit that stores information based on a result of reception of the light output to the first path by putting the path-switching-unit into the first state and then controls power of the pump light on a basis of the stored information and a result of reception of the first light output by the splitting-unit by putting the path-switching-unit into the second state.

Abstract: An optical transmission system includes: a first optical transmission device configured to perform bidirectional optical transmission with a second optical transmission device via an optical transmission line, wherein the first optical transmission device includes a transmitted light power adjusting section configured to transmit, to the second optical transmission device, a first light power which is set based on a measurement result, the second transmission device measuring a fluctuating light power transmitted from the first transmission device and informing the first transmission device of the measurement result.

Abstract: There is provided a control circuit for a transmission system in which signal light transmitted from a transmission-side apparatus via a transmission path to a reception-side apparatus is subjected to Raman amplification by inputting excitation light from the reception-side apparatus to the transmission path. The control circuit includes a first detection unit configured to detect a change amount of an optical loss of the transmission path caused by a state change of the transmission path, a second detection unit configured to detect a backscattered light amount of the excitation light, and a control unit configured to control an intensity of the excitation light input by the reception-side apparatus to the transmission path on the basis of the change amount of the optical loss detected by the first detection unit and the backscattered light amount detected by the second detection unit.

Abstract: An optical amplifying device includes an optical amplification medium configured to be excited by excitation light and amplify signal light, a light loss detector configured to detect a light loss of an optical component optically connected to the optical amplification medium in the amplifying device, and a noise figure deterioration detector configured to detect, based on the light loss detected by the light loss detector, deterioration of a noise figure of the optical amplification medium.

Abstract: Raman amplifier includes: a pump-light generator configured to supply pump light to a transmission fiber; a measurement circuit configured to measure a relationship between power of the pump light and power of noise output from the transmission fiber with respect to a range from first pump-light power to second pump-light power; a signal detector configured to monitor a supervisory signal in output light of the transmission optical; and a decision unit configured to decide a state of the transmission fiber according to the monitoring result. When the supervisory signal is detected without the pump light, the measurement circuit measures the relationship while increasing the power of the pump light from the first pump-light power. When the supervisory signal is not detected without the pump light, the measurement circuit measures the relationship while decreasing the power of the pump light from the second pump-light power.