Patent ID: 6778317
Filing Date: 2004-08-17
Classification: G02F

Abstract:
A demodulator for coherent demodulation of an optical input signal, the demodulator comprising,an optical local oscillator for providing a optical local oscillator signal, a guided media for communicating the optical input signal, the guided media having phase perturbations effecting the optical input signal, a mixer for receiving a phase shifted optical local oscillator signal and for demodulating the optical input signal into an RF output signal having an RF frequency error component, an error detector for receiving RF frequency error component and an RF frequency reference for providing a frequency error signal, and a phase shifter driven by the frequency error signal for phase shifting the local oscillator signal into the phase shifted local oscillator signal, the phase shifted local oscillator signal being coherent with the optical input signal prior to demodulating the optical input signal into the RF output signal during the phase perturbations of the optical input signal communicated through the guided media.