Patent ID: 8406638

Claim:
A coherent light receiver comprising: an optical mixer to couple local oscillator light and reception signal light; a photoelectric converter to photoelectrically convert coupled signal light obtained by a coupling operation of the optical mixer to an analogue electrical signal; an analogue-to-digital converter to convert, the analogue electrical signal to a sampled digital electrical signal; a reception data processing unit to extract reception data included in the reception signal light of the coupled signal light through a digital signal processing for processing, synchronously with a first clock, the coupled signal converted into the sampled digital electrical signal by the analogue-to-digital converter; an oscillation circuit to generate the first clock, and supply the first clock to the reception data processing unit; a modulation clock supply unit to generate a clock phase-synchronized with the first clock and supply the generated clock to the modulator, the generated clock having a repeating frequency of one integral-th or integral times of the frequency of the first clock; and a modulator to modulate the local oscillator light or the reception signal light to be inputted to the optical mixer respectively, by using the clock phase-synchronized with the first clock.