Abstract: An optical network device includes a receiver that receives a polarization multiplexed optical signal and a processor. The processor separates an electric field information signal indicating the polarization multiplexed optical signal into first and second polarization components orthogonal to each other, generates third and fourth polarization components by controlling the first and second polarization components, calculates an evaluation value corresponding to a power of the third or fourth polarization component for each of a plurality of positions on a transmission line, calculates a variation in the evaluation value for a control amount for each of the plurality of positions, and decides whether a first position is a position to be detected based on a result of comparing a variation in an evaluation value for the first position with a variation in an evaluation value for a second position adjacent to the first position.

Abstract: An optical network device includes a receiver that receives a polarization multiplexed optical signal and a processor. The processor separates an electric field information signal indicating the polarization multiplexed optical signal into first and second polarization components orthogonal to each other, generates third and fourth polarization components by controlling the first and second polarization components, calculates an evaluation value corresponding to a power of the third or fourth polarization component for each of a plurality of positions on a transmission line, calculates a variation in the evaluation value for a control amount for each of the plurality of positions, and decides whether a first position is a position to be detected based on a result of comparing a variation in an evaluation value for the first position with a variation in an evaluation value for a second position adjacent to the first position.

Abstract: A transmission device includes a first optical modulator configured to modulate, based on a packet signal for each of packets, input light into an optical packet signal and to output an optical packet signal for each of the packets; a generation circuit configured to generate an adjustment signal that adjusts slopes of a rise and a fall of a waveform of the optical packet signal; and a second optical modulator configured to modulate the optical packet signal from the first optical modulator and adjust, based on the adjustment signal, the slopes of the rise and the fall of the waveform of the optical packet signal.

Abstract: An optical receiver, includes: a signal processor to perform digital signal processing on a polarization demultiplexed signal obtained by demultiplexing a polarization multiplexed signal corresponding to a reception signal, the signal processor includes: an adaptive equalization circuit to compensate for the polarization demultiplexed signal by control of a filter coefficient; a first frequency offset estimation circuit to receive a first polarization demultiplexed signal diverged at a preceding stage and estimate a first frequency offset; a second frequency offset estimation circuit to receive a second polarization demultiplexed signal diverged at a succeeding stage and estimate a second frequency offset; and a decision circuit to decide whether the filter coefficient is correct based on a first difference between the first frequency offset and the second frequency offset and output, when deciding that the filter coefficient is incorrect, a first trigger for re-calculation of the filter coefficient.

Abstract: An optical receiver, includes: a signal processor to perform digital signal processing on a polarization demultiplexed signal obtained by demultiplexing a polarization multiplexed signal corresponding to a reception signal, the signal processor includes: an adaptive equalization circuit to compensate for the polarization demultiplexed signal by control of a filter coefficient; a first frequency offset estimation circuit to receive a first polarization demultiplexed signal diverged at a preceding stage and estimate a first frequency offset; a second frequency offset estimation circuit to receive a second polarization demultiplexed signal diverged at a succeeding stage and estimate a second frequency offset; and a decision circuit to decide whether the filter coefficient is correct based on a first difference between the first frequency offset and the second frequency offset and output, when deciding that the filter coefficient is incorrect, a first trigger for re-calculation of the filter coefficient.

Abstract: An optical digital coherent receiver includes: a polarization separation circuit configured to perform polarization separation on a received signal and output polarized signals; and a determination circuit configured to trigger a start of digital signal processing in a stage subsequent to the polarization separation circuit when it is determined that a distribution of a peak of an amplitude of one of the polarized signals has a characteristic corresponding to a modulation method used on a transmitting side.

Abstract: An optical digital coherent receiver includes: a polarization separation circuit configured to perform polarization separation on a received signal and output polarized signals; and a determination circuit configured to trigger a start of digital signal processing in a stage subsequent to the polarization separation circuit when it is determined that a distribution of a peak of an amplitude of one of the polarized signals has a characteristic corresponding to a modulation method used on a transmitting side.

Abstract: A signal processing apparatus includes a number P of adaptive equalization filters, P being 2 or more, configured to execute a first computing process for equalization on respective input signals, and to issue output signals; a number N of error calculation circuits, N being not more than P, configured to determine, per adaptive equalization filter, a second computing process to calculate an error in order to reduce a difference between a value of the output signal obtained with the first computing process and a predetermined objective value of the output signal; and an update circuit configured to determine a third computing process based on the second computing process determined per adaptive equalization filter by the error calculation circuit, and to update a computing process, which is executed in the adaptive equalization filter, to the third computing process.