Optical receiver

An optical receiver comprising:

• a coherent receiver to receive an optical signal;
• an A/D converter to convert an output signal of the coherent receiver into a digital signal representing the optical signal;
• a waveform distortion compensator to perform an operation on the digital signal to compensate for waveform distortion of the optical signal;
• a phase detector to generate phase information representing a sampling phase of the A/D converter;
• a phase adjuster to generate a digital signal representing an optical signal in which the sampling phase of the A/D converter is adjusted from an output signal of the waveform distortion compensator using the phase information;
• a demodulator to generate a demodulated signal from the output signal of the phase adjuster;
• a polarization controller to control a rotation angle of polarization of the optical signal;
• a peak detector to detect a peak value of the phase information while the polarization of the optical signal is controlled by the polarization controller;
• and
• a compensation controller to control the waveform distortion compensator using the peak value.

An optical receiver comprising:

• a coherent receiver to receive an optical signal;
• an A/D converter to convert an output signal of the coherent receiver into a digital signal representing the optical signal;
• a waveform distortion compensator to perform operation on the digital signal to compensate for waveform distortion of the optical signal;
• a phase detector to generate phase information representing a sampling phase of the A/D converter;
• a phase adjuster to generate a digital signal representing an optical signal in which the sampling phase of the A/D converter is adjusted from an output signal of the waveform distortion compensator using the phase information;
• a demodulator to generate a demodulated signal from the output signal of the phase adjuster;
• a fluctuation controller to fluctuate the phase information by one period or more;
• a peak detector to detect a peak value of the phase information while the phase information is controlled by the fluctuation controller;
• and
• a compensation controller to control the waveform distortion compensator using the peak value.

A digital signal processor used in an optical receiver including a coherent receiver to receive an optical signal and an A/D converter to convert an output signal of the coherent receiver into a digital signal representing the optical signal, comprising:

• a waveform distortion compensator to perform operation on the digital signal to compensate for waveform distortion of the optical signal;
• a phase detector to generate phase information representing a sampling phase of the A/D converter;
• a phase adjuster to generate a digital signal representing an optical signal in which the sampling phase of the A/D converter is adjusted from an output signal of the waveform distortion compensator using the phase information;
• a demodulator to generate a demodulated signal from the output signal of the phase adjuster;
• a phase controller to control the sampling phase of the A/D converter;
• a peak detector to detect a peak value of the phase information while the sampling phase of the A/D converter is controlled by the phase controller;
• and
• a compensation controller to control the waveform distortion compensator using the peak value.

A digital signal processor used in an optical receiver including a coherent receiver to receive an optical signal and an A/D converter to convert an output signal of the coherent receiver into a digital signal representing the optical signal, comprising:

• a waveform distortion compensator to perform an operation on the digital signal to compensate for waveform distortion of the optical signal;
• a phase detector to generate phase information representing a sampling phase of the A/D converter;
• a phase adjuster to generate a digital signal representing an optical signal in which the sampling phase of the A/D converter is adjusted from an output signal of the waveform distortion compensator using the phase information;
• a demodulator to generate a demodulated signal from the output signal of the phase adjuster;
• a polarization controller to control a rotation angle of polarization of the optical signal;
• a peak detector to detect a peak value of the phase information while the polarization of the optical signal is controlled by the polarization controller;
• and
• a compensation controller to control the waveform distortion compensator using the peak value.