Digital coherent receiving apparatus

摘要

A digital coherent receiving apparatus includes a first oscillator for outputting a local light signal of a fixed frequency, a hybrid unit mixing the local light signal with a light signal received by a receiver, a second oscillator for outputting a sampling signal of a sampling frequency, a converter for converting the mixed light signal into digital signal synchronizing with the sampling signal, a waveform adjuster for adjusting a waveform distortion of the converted digital signal, a phase adjustor for adjusting a phase of the digital signal adjusted by the waveform adjustor, a demodulator for demodulating the digital signal adjusted by the phase adjuster, and a phase detector for detecting a phase of the digital signal adjusted by the phase adjuster, and a control signal output unit for outputting a frequency control signal on the basis of the detected phase signal to the second oscillator.

主权项

1. A digital coherent receiving apparatus, comprising:
a receiver configured to receive a light signal; a first oscillator configured to output a local light signal; a 90° optical hybrid circuit configured to mix the local light signal output from the first oscillator with the light signal received by the receiver; a second oscillator configured to output a sampling signal of a sampling frequency, the second oscillator changing the sampling frequency in response to an input control signal; a converter configured to convert the mixed light signal into a digital signal by sampling the mixed light signal with the sampling signal; a waveform adjuster configured to adjust a waveform distortion of the digital signal converted by the converter; a phase detector configured to detect a phase signal of the digital signal adjusted by the waveform adjuster; a control signal output unit configured to output a control signal based on the detected phase signal to the second oscillator; a phase adjuster configured to adjust a phase of the digital signal adjusted by the waveform adjuster; and a demodulator configured to demodulate the digital signal adjusted by the phase adjuster, wherein the phase detector includes: a plurality of equalizing filters configured to respectively process and equalize the digital signal using different equalizing characteristics, a plurality of detecting units configured to detect a plurality of candidate phases of the digital signal processed by each of the equalizing filters, and a selector configured to select one of the detected candidate phases as the detected phase.