Method and apparatus for laser frequency stabilization

Abstract

A method and apparatus for laser frequency stabilization and precise laser frequency tuning comprises splitting a laser beam into two beam portions and recombining the two portions after they traverse differing optical distances. The thus-processed combined beam exhibits a time variation in intensity, the time variation being a function of the time rate of change of the laser beam. A signal proportional to the laser frequency's time rate of change is derived from the time variation of the processed beam's intensity and used to generate a control signal to provide feedback to control the laser frequency, thereby providing for laser frequency stabilization. Precise laser frequency tuning may be achieved by introducing a controlled variation in the derived signal, such as by adjusting a frequency differential introduced between the beam portions, or by otherwise introducing a controlled variation in the signal derived from the processed beam. The timescale over which laser frequency stabilization is achieved may be increased or decreased, and the bandwidth of the stabilization capability increased, by use of one or more additional processed and combined beams having time delays, between the portions to be combined, different from the corresponding time delay in the first processed beam and from each other.