Absolute frequency stabilization of the Nd: YAG laser

Stablized, single-frequency Nd:YAG lasers are of current interest for use in communication systems, holography and parametric converters. Stabilization requires a frequency discriminant which is characteristically provided by a high finesse passive Fabry-Perot cavity in a wide bandwidth control loop to compensate for short-term frequency fluctuations and an atomic line discriminant to maintain long-term stability. This scheme, used successfully with gas lasers, is not directly applicable to the Nd:YAG laser due to the absence of narrow line width absorbers near the 1.06 micron operating range. There are, however, numerous absorption lines of iodine at the frequncy doubled wavelength of the Nd:YAG laser.