Frequency stabilization of Nd:YAG lasers to Cs-133(2) sub-Doppler lines near 1064 nm

Sub-Doppler lines of Cs-2 were investigated with a Nd:YAG laser. Modulation transfer spectroscopy and FM spectroscopy were applied to yield error signals that were used for absolute stabilization of the laser frequency. The frequency stability was characterized with an It-locked dual-wavelength Nd:YAG frequency reference. The root Allan variance of the beat frequency reached a minimum of 1.3 x 10(-11) (beat frequency fluctuations of 3.65 kHz) for a measurement time of 20 s. Absolute frequencies of several Cst lines were determined with an accuracy of similar to 1 MHz. Further improvement in sensitivity was demonstrated by insertion of the absorption cell into a Fabry-Perot cavity. While the laser was locked to the cavity, the cavity length was modulated and the transmitted probe beam was detected at the third harmonic of the modulation frequency. (C) 1996 Optical Society of America