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. Modul ation transfer spectroscopy and FM spectroscopy were applied to yield error signals that were used for absolute stabilization of the laser f requency. 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 fr equencies of several Cst lines were determined with an accuracy of sim ilar 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 th e transmitted probe beam was detected at the third harmonic of the mod ulation frequency. (C) 1996 Optical Society of America