Fujitsu Corporation

Eri Katayama

Kiichi Sugitani

Takahito Tanimura

Kazunari Shiota

Setsuo Yoshida

Kazuyuki Tajima

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.

Optical network device and method for monitoring transmission line

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.

Optical receiver and optical receiving method

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.

Growing community of inventors

Fukuoka, Japan

Eri Katayama