Patent ID: 7869472

Claim:
A device, comprising: a laser that produces a laser output beam at a laser frequency; an optical interferometer located in an optical path of the laser output beam and comprising a first optical path that receives a first portion of the laser output beam, a second optical path that receives a second portion of the laser output beam, and an optical combiner where the first and second optical paths meet each other and terminate, the optical combiner (1) transmitting a part of light from the first optical path and reflecting a part of light from the second optical path to produce a first combined optical output, and (2) transmitting a part of the light from the second optical path and reflecting a part of the light from the first optical path to produce a second combined optical output; an optical resonator optically coupled in the first optical path to filter light in the first optical path; a detection module that detects the first and the second combined optical outputs to produce an error signal representing a frequency difference between the laser frequency and a resonance of the optical resonator; and a feedback control mechanism that receives the error signal and tunes, one of (1) the laser and (2) the optical resonator, in response to the frequency difference of the error signal to lock the laser and the optical resonator with respect to each other.