CW Laser wavemeter/frequency locking technique

Abstract

A wavemeter/frequency locking technique suitable for indirectly locking an optical frequency f.sub.0 to a radio frequency f.sub.1 or for locking the radio frequency to the optical frequency. A beam of optical frequency f.sub.0 is phase modulated by a signal of average frequency f.sub.1 that is itself modulated at frequency f.sub.2. The modulated beam is passed through a filter to a detector to produce a detector output signal that has components at linear integral sums of f.sub.1 and f.sub.2. A pair of control signals are generated that are proportional to the amplitude of two of the components of the detector output signal. These control signals are separately used in a pair of servo loops to separately establish fixed values of f.sub.0 /f.sub.f and f.sub.1 /f.sub.f, where f.sub.f is a characteristic frequency of the filter. A method is presented for stepping the value of f.sub.0 /f.sub.f to another value and measuring f.sub.1 /f.sub.2 at each of these values, thereby enabling the value of f.sub.0 to be determined.

Dependencies are inferred from the claim text.