Laser spectroscopy of molecular cesium near 1064 nm enhanced by a fabry–perot cavity

We made Doppler-broadened and Doppler-free absorption measurement of a cesium cell that was placed inside an external Fabry–Perot ring cavity, using a Nd:YAG laser. We achieved a cavity finesse of ˜85, and the sensitivity of the measurement was improved by as much as 26.5 with respect to single-pass absorption. The sensitivity enhancement by the external cavity may enable one to lock the laser frequency to¹³³Cs₂ lines at relatively low temperatures, in which the frequency-dependent temperature shift, as well as the collision broadening, is reduced significantly.