Optical transmission and reception device and optical receiver

An optical transmission and reception device comprising:

• an optical transmitter;
• and
• an optical receiver, wherein
• the optical transmitter includes:
• a modulation signal generator to generate a modulation signal that is a digital signal for optical modulation in which a first pilot symbol signal having a first symbol period and a second pilot symbol signal having a second symbol period different from the first symbol period are inserted into data to be transmitted;
• a digital-to-analog converter to convert the modulation signal that is the digital signal generated by the modulation signal generator into a modulation signal including an analog signal;
• and
• an optical modulator to generate modulated light into which the first pilot symbol signal having the first symbol period and the second pilot symbol signal having the second symbol period are inserted by modulating CW light from a CW light generator on a basis of the modulation signal converted into the analog signal by the digital-to-analog converter, and
• the optical receiver includes:
• an optical coherent detector to receive polarization-multiplexed modulated light into which the first pilot symbol signal having the first symbol period and the second pilot symbol signal having the second symbol period different from the first symbol period are inserted, coherently detect the received modulated light, and output an analog electric signal;
• an analog-to-digital converter to perform analog-to digital conversion on the analog electric signal from the optical coherent detector to output the signal as a digital signal;
• and
• a reception-side digital signal processor including a frequency difference compensator to receive the digital signal from the analog-to-digital converter, calculate a phase difference using the first pilot symbol signal having the first symbol period and the second pilot symbol signal having the second symbol period different from the first symbol period and adjacent to the first pilot symbol signal, the first pilot symbol signal and the second pilot symbol signal being inserted into the received polarization-multiplexed modulated light extracted from the received digital signal, and compensate a frequency of the received digital signal.