Patent ID: 6175579
Filing Date: 2001-01-16
Classification: H01S

Abstract:
A laser frequency control apparatus comprising:(a) an optical resonator having an optical length and a plurality of resonant modes dependent upon said optical length;(b) a first laser system including a first laser output at a first laser frequency and a first laser locking mechanism, said first laser locking mechanism adapted to modulate said first laser output so as to lock said first laser frequency to a first resonant mode of said optical resonator;(c) a second laser system including a second laser output at a second laser frequency and a second laser locking mechanism, said second laser locking mechanism adapted to modulate said second laser output so as to lock said second laser frequency to a second resonant mode of said optical resonator;(d) a beatnote generator arranged to receive said first and second laser outputs and produce a beatnote signal representative of the difference between said first and second laser frequencies;(e) a modulation device adapted to modulate said optical length so as to maintain a specific optical length; and(f) a negative feedback system having said beatnote signal and a reference signal as input signals and producing a modulation signal to actuate said modulation device to modulate said optical length responsive to said beatnote signal so as to lock said optical resonator to said reference signal.