CO2-LASER STABILIZATION TO 0.1-HZ LEVEL USING EXTERNAL ELECTROOPTIC MODULATION

We have developed a frequency stabilization scheme for CO2 lasers usin g only external modulation via an electrooptic modulator (EOM). One of the two laser sidebands which ape generated by the EOM and frequency- modulated is set in resonance with a Fabry-Perot cavity, itself filled with OsO4 as an absorber. The saturation signal of an OsO4 line detec ted in transmission of the Fabry-Perot cavity is used for stabilizatio n. We obtained a stability of 0.1 Hz (Delta nu/nu = 3.510(-15)) on a 1 00-s time scale, and a reproducibility up to 10 Hz with the strongest OsO4 reference lines. These results; largely improve the performance o f our previous setup for which modulation was applied through piezoele ctric transducers. Further, the stabilized laser is not frequency-modu lated and easily tunable.