Light receiving device and light receiving method
A light receiving device includes: a converter digitalizing an analog signal with a given sampling clock frequency, the analog signal being obtained through a photoelectric conversion of a received optical signal; a plurality of fixed distortion compensators compensating an output signal of the converter for waveform distortion with a fixed compensation amount that is different from each other; a plurality of phase shift detector circuits detecting a sampling phase shift from an output signal of the plurality of the fixed distortion compensators; a phase-adjusting-amount determiner determining a sampling phase adjusting amount with use of an output signal of the plurality of the phase shift detector circuits; and a phase adjusting circuit reducing a phase difference between the sampling clock frequency and the received optical signal based on a determination result of the phase-adjusting-amount determiner.
1. A light receiving device comprising:
a converter to digitalize an analog signal with a given sampling clock frequency, the analog signal being obtained through a photoelectric conversion of a received optical signal;
a plurality of fixed distortion compensators to compensate an output signal of the converter for waveform distortion with a fixed compensation amount that is different from each other;
a plurality of compensation amount detector to detect a distortion compensation amount based on a phase-shift-detection sensitivity of each output signal of the plurality of the fixed distortion compensators;
a distortion compensator to compensate for distortion with a distortion compensation amount detected by the compensation amount detector;
a phase-adjusting-amount determiner to determine a sampling phase adjusting amount with use of an output signal of the phase shift detector circuit; and
a phase adjusting circuit to reduce a phase difference between the sampling clock frequency and the received optical signal based on a determination result of the phase-adjusting-amount determiner.
2. The light receiving device as claimed in claim 1 further comprising a semi-fixed digital filter to compensate an output signal of the converter for waveform distortion,
wherein:
compensation amount of the semi-fixed digital filter is corrected based on a compensation amount detected by the compensation amount detector; and
the plurality of the fixed distortion compensators compensate an output signal of the semi-fixed digital filter for waveform distortion with a fixed compensation amount that is different from each other.
3. The light receiving device as claimed in claim 1 , wherein the fixed distortion compensator compensates for chromatic dispersion as the waveform distortion compensation.
4. The light receiving device as claimed in claim 1 , wherein the phase adjusting circuit includes a digital phase adjusting circuit adjusting a phase of an output signal of the converter.
5. The light receiving device as claimed in claim 1 , wherein the phase adjusting circuit includes a corrector correcting a sampling clock frequency of the converter.
6. A light receiving method comprising:
digitalizing an analog signal with a given sampling clock frequency, the analog signal being obtained through a photoelectric conversion of a received optical signal;
compensating an output signal obtained in the digitalizing for waveform distortion with a fixed compensation amount that is different from each other;
detecting a distortion compensation amount based on a phase-shift-detection sensitivity of each output signal obtained in the compensating for the waveform;
compensating for distortion with a distortion compensation amount detected in the detecting;
determining a sampling phase shift amount with use of an output signal obtained in the compensating for the distortion; and
reducing a phase difference between the sampling clock frequency and the received optical signal based on a determination result of the determining.
7. The light receiving method as claimed in claim 6 further comprising correcting compensation amount of a semi-fixed digital filter compensating an output signal obtained in the converting for waveform distortion with a compensation amount detected in the detecting,
wherein waveform distortion is compensated for with respect to an output signal of the semi-fixed digital filter with a fixed compensation amount that is different from each other in the compensating for the waveform.
8. The light receiving method as claimed in claim 6 further comprising adjusting a phase of a signal obtained in the converting.
9. The light receiving method as claimed in claim 7 further comprising adjusting a phase of a signal obtained in the converting.
10. The light receiving method as claimed in claim 6 , wherein chromatic dispersion is compensated for as waveform distortion compensation in the compensating for the waveform.
11. The light receiving method as claimed in claim 7 , wherein chromatic dispersion is compensated for as waveform distortion compensation in the compensating for the waveform.
12. The light receiving method as claimed in claim 6 further comprising correcting a sampling clock frequency in the converting based on a determination result of the determining.
13. The light receiving method as claimed in claim 7 further comprising correcting a sampling clock frequency in the converting based on a determination result of the determining.