Patent ID: 7949261

Claim:
An optical receiver comprising: a. a demodulator having a delay interferometer comprising an optical input that receives a phase modulated optical signal from a transmission system, a constructive optical output, and a destructive optical output, the delay interferometer configured to have a delay that is less than one symbol slot and that is selected according to a bandwidth of the transmission system, wherein the transmission system has a FWHM bandwidth of an intensity transfer function as seen from a transmitter modulator, which generates the phase modulated optical signal, to the input of the demodulator that is less than twice the symbol rate and wherein an improvement in a performance characteristic of the optical receiver is achieved relative to the performance characteristic for a delay of one symbol slot; and b. a differential detector comprising a first and a second photodetector, the first photodetector being optically coupled to the constructive optical output of the delay interferometer, the second photodetector being optically coupled to the destructive optical output of the delay interferometer, the differential detector combining a first electrical detection signal generated by the first photodetector and a second electrical detection signal generated by the second photodetector to generate an electrical reception signal.