Patent ID: 7389053

Claim:
A device, comprising: a laser to produce a laser beam at a laser carrier frequency; an optical modulator to modulate the laser beam in response to an input signal to produce a modulated laser beam that carries the input signal; an input optical port to receive the modulated laser beam; a first optical path coupled to the input optical port to receive a first portion of the modulated laser beam and comprising a plurality of first tunable optical resonators optically cascaded to transmit light at the laser carrier frequency through the first optical path; a second optical path coupled to the input optical port to receive a second portion of the modulated laser beam and comprising a plurality of second tunable optical resonators optically cascaded to transmit light at a selected optical frequency different from the laser carrier frequency through the second optical path; an output optical port coupled to the first and second optical paths to combine transmitted light from the first and second optical paths to produce an output optical beam; and an optical detector to convert the output optical beam into an output signal carrying a signal component of the input signal at a frequency that is a difference between the optical carrier frequency and the selected optical frequency.