Patent ID: 7609982

Claim:
A RZ-DPSK optical receiver circuit comprising: an interferometer, comprising a 1-symbol delaying element in one of paired optical paths, for transmitting an input RZ-DPSK signal via the paired optical paths; a photo detector circuit for converting an optical signal output from said interferometer into an electrical signal; a high-pass filter with a cut-off frequency which is equal or approximately equal to the symbol rate of the RZ-DPSK signal, for filtering an output signal of said photo detector circuit; and a BPSK demodulator circuit for demodulating an output signal of said high-pass filter, wherein said interferometer outputs a pair of complementary optical signals, and said photo detector circuit comprises a pair of photodiodes for respectively converting the pair of the optical signals into a pair of electrical signals and outputs a differential signal of the pair of electrical signals acquired by the pair of photodiodes, and said high-pass filter acquires a BPSK signal from the differential signal, and said BPSK demodulator circuit demodulates the BPSK signal.