Abstract: An optical logic circuit includes a NOT circuit. The NOT circuit reflects by fixed end reflection an data pulse input into the optical logic circuit which is an ON pulse of which a wavelength and an intensity are similar to a wavelength and an intensity of a standard optical pulse or an OFF pulse obtained by applying OFF modulation to the standard optical pulse. The NOT circuit multiplexes the reflected data pulse and the standard optical pulse and outputs the multiplexed pulse.

Abstract: A frequency conversion device includes: an optical convertor configured to convert a source modulated light into an unmodulated light; and a frequency convertor configured to use the unmodulated light converted by the optical convertor as a reference light and convert the source modulated light into a modulated light that has a desirable frequency.

Abstract: A probe generator includes: a first demultiplexer configured to branch a first optical signal having a first wavelength into at least two first polarized optical signals; a first adjustor configured to adjust the first polarized optical signals such that the first polarized optical signals have the same polarization direction and to combine the adjusted first polarized optical signals into a second optical signal; a first modulator configured to branch the second optical signal into at least two first split optical signals and to intensity-modulate each of the first split optical signals with first pilot signals; a second adjustor configured to adjust the first split optical signals intensity-modulated by the first modulator such that the intensity-modulated first split optical signals have different polarization directions; and an output unit configured to combine the first split optical signals adjusted by the second adjustor to generate a probe optical signal to be output.

Abstract: An optical receiver includes: an optical brancher configured to branch polarization multiplexed light to a first polarization multiplexed light and a second polarization multiplexed light, the polarization multiplexed light in which a pilot signal is superimposed on at least one of a first polarization and a second polarization; an optical fiber configured to transmit the first polarization multiplexed light; a first polarization rotator configured to control a first polarization state of the first polarization multiplexed light output from the optical fiber; a first polarization separator configured to separate the second polarization multiplexed light into a third polarization and a fourth polarization; and a controller configured to control the first polarization rotator based on one of a first pilot signal included in the third polarization and a second pilot signal included in the fourth polarization.

Abstract: An optical transceiver includes: a light source; a light source power management unit configured to manage a state of an output power of the light source; an optical detector configured to receive a first optical signal from a counterpart optical transmission apparatus and detect the first optical signal; and a monitoring information extraction unit configured to extract a monitoring information of a reception power level of a second optical signal, which is generated from an output light of the light source and received in the counterpart optical transmission apparatus, from the first optical signal, wherein the light source power management unit is configured to update a written value of the state of the output power of the light source in a case where a monitored value of the reception power level included in the monitoring information is decreased to exceed a variation of an optical transmission path.

Abstract: A probe generator includes: a first demultiplexer configured to branch a first optical signal having a first wavelength into at least two first polarized optical signals; a first adjustor configured to adjust the first polarized optical signals such that the first polarized optical signals have the same polarization direction and to combine the adjusted first polarized optical signals into a second optical signal; a first modulator configured to branch the second optical signal into at least two first split optical signals and to intensity-modulate each of the first split optical signals with first pilot signals; a second adjustor configured to adjust the first split optical signals intensity-modulated by the first modulator such that the intensity-modulated first split optical signals have different polarization directions; and an output unit configured to combine the first split optical signals adjusted by the second adjustor to generate a probe optical signal to be output.

Abstract: An optical logic circuit includes a NOT circuit. The NOT circuit reflects by fixed end reflection an data pulse input into the optical logic circuit which is an ON pulse of which a wavelength and an intensity are similar to a wavelength and an intensity of a standard optical pulse or an OFF pulse obtained by applying OFF modulation to the standard optical pulse. The NOT circuit multiplexes the reflected data pulse and the standard optical pulse and outputs the multiplexed pulse.

Abstract: An optical limiter includes a nonlinear medium that changes its own refractive index in accordance with an intensity of incident light, and outputs the incident light in a different direction depending on the refractive index, a first incident section by which reference light with a predetermined intensity and an optical signal with a modulated intensity is made incident on the nonlinear medium, a second incident section by which auxiliary light is made incident on a portion in the nonlinear medium through which the reference light and the optical signal pass, and an inverse output section that is provided at an incident position of the reference light outputted from the nonlinear medium when the optical signal is off, and outputs an optical signal obtained by inversion of the intensity of the incident light.

Abstract: An optical transceiver includes: a light source; a light source power management unit configured to manage a state of an output power of the light source; an optical detector configured to receive a first optical signal from a counterpart optical transmission apparatus and detect the first optical signal; and a monitoring information extraction unit configured to extract a monitoring information of a reception power level of a second optical signal, which is generated from an output light of the light source and received in the counterpart optical transmission apparatus, from the first optical signal, wherein the light source power management unit is configured to update a written value of the state of the output power of the light source in a case where a monitored value of the reception power level included in the monitoring information is decreased to exceed a variation of an optical transmission path.

Abstract: An optical branching device includes: a Faraday rotator capable of controlling polarized wave of input light based on a change of a magnetic flux density depending on a magnetic field to be provided; a magnet configured to provide the Faraday rotator with the magnetic field; a polarization beam splitter configured to branch, by a polarized wave component, the input light which passes through the Faraday rotator; a bimetal configured to deform depending on a temperature; and a controller configured to have a mechanism to use force accompanying with the deformation of the bimetal so as to control a relative positional relationship between the Faraday rotator and the magnet.

Abstract: A frequency conversion device includes: an optical convertor configured to convert a source modulated light into an unmodulated light; and a frequency convertor configured to use the unmodulated light converted by the optical convertor as a reference light and convert the source modulated light into a modulated light that has a desirable frequency.

Abstract: An optical branching device includes: a Faraday rotator capable of controlling polarized wave of input light based on a change of a magnetic flux density depending on a magnetic field to be provided; a magnet configured to provide the Faraday rotator with the magnetic field; a polarization beam splitter configured to branch, by a polarized wave component, the input light which passes through the Faraday rotator; a bimetal configured to deform depending on a temperature; and a controller configured to have a mechanism to use force accompanying with the deformation of the bimetal so as to control a relative positional relationship between the Faraday rotator and the magnet.

Abstract: An optical limiter includes a nonlinear medium that changes its own refractive index in accordance with an intensity of incident light, and outputs the incident light in a different direction depending on the refractive index, a first incident section by which reference light with a predetermined intensity and an optical signal with a modulated intensity is made incident on the nonlinear medium, a second incident section by which auxiliary light is made incident on a portion in the nonlinear medium through which the reference light and the optical signal pass, and an inverse output section that is provided at an incident position of the reference light outputted from the nonlinear medium when the optical signal is off, and outputs an optical signal obtained by inversion of the intensity of the incident light.

Abstract: An optical receiver includes: an optical brancher configured to branch polarization multiplexed light to a first polarization multiplexed light and a second polarization multiplexed light, the polarization multiplexed light in which a pilot signal is superimposed on at least one of a first polarization and a second polarization; an optical fiber configured to transmit the first polarization multiplexed light; a first polarization rotator configured to control a first polarization state of the first polarization multiplexed light output from the optical fiber; a first polarization separator configured to separate the second polarization multiplexed light into a third polarization and a fourth polarization; and a controller configured to control the first polarization rotator based on one of a first pilot signal included in the third polarization and a second pilot signal included in the fourth polarization.

Abstract: In accordance with the present disclosure, disadvantages and problems associated with polarization dependent effects of a polarization multiplexed optical signal may be reduced through polarization scrambling. In accordance with an embodiment of the present disclosure a method for detecting polarization scrambling of a polarization multiplexed optical signal comprises receiving a polarization multiplexed optical signal associated with an optical network. The polarization multiplexed optical signal including a scrambled polarization orientation, the polarization orientation scrambled according to a scrambling frequency. The method further comprising receiving a polarization signal indicating the polarization scrambling of the received optical signal. The method additionally comprises descrambling the optical signal according to the polarization scrambling as indicated by the polarization signal.

Abstract: A transmission-path-type specifying apparatus includes an optical filter that extracts a plurality of different wavelength components from light including wavelength components occurring at the time of communication; an optical switch that simultaneously transmits same pulse signals superposed on light of the extracted wavelength components. The apparatus also includes an ASE modulation controlling unit that obtains a delay-time difference among the transmitted pulse signals when arriving at a destination via a transmission path; a characteristic-value calculating unit that calculates a characteristic value of the transmission path corresponding to a reference time varied depending on the obtained delay-time difference and a type of the transmission path; and a fiber-type determining unit that specifies the type of the transmission path based on the calculated characteristic value.

Abstract: An optical communication system includes an optical transmission terminal including a first transmitter for transmitting an optical signal, and a second transmitter for transmitting information that indicates the first transmitter transmitting the optical signal; and an optical receiving terminal including an optical receiver for receiving the optical signal and the information transmitted from the first and second transmitter, respectively, a storage device for storing a power value of the optical signal monitored in response to receipt of the information transmitted from the second transmitter, and a fault detector for detecting fault of the optical signal by continuously monitoring a power value of the optical signal received by the optical receiver in comparison with the power value stored in the storage device.

Abstract: An optical signal demultiplexing device includes a demultiplexing unit that receives an optical signal multiplexed by an optical time-division system and a synchronization pattern, and demultiplexes the optical signal based on the synchronization pattern. The optical signal demultiplexing device also includes a pulse-width increasing unit that makes optical signals demultiplexed by the demultiplexing unit generate chirp, and increases the pulse widths of the optical signals generating the chirp by passing the optical signals through a wavelength dispersion medium.

Abstract: An optical signal transmission control apparatus that controls transmission of optical signals transmitted via a plurality of redundant routes. The optical signal transmission control apparatus includes a delay difference adjusting unit that adjusts a transmission delay difference between the optical signals of each route by converting a wavelength of the optical signal and making the optical signal with a converted wavelength pass through a waveguide in which a transmission delay of the optical signal changes continuously depending on the wavelength, and a waveform degradation compensating unit that compensates degradation of a waveform of the optical signal, while maintaining the transmission delay difference adjusted by the delay difference adjusting unit.

Abstract: There is provided an optical transmission apparatus including: a plurality of wavelength selective switches including input ports, a transmission port, and monitor port used to output a light switched so that the light from the input port is monitored; a multiplexer to combine the lights output from the transmission ports of the plurality of wavelength selective switches; a monitor to monitor whether a same wavelength of the light output from the monitor port exists in wavelengths of the lights combined by the multiplexer; and a controller to control the wavelength selective switch so as to output, from the transmission port, the light switched to the monitor port in case that the same wavelength of the light output from the monitor port is absent in wavelengths of the lights combined by the multiplexer, based on a monitor result by the monitor.