LASER FREQUENCY DIVISION BY DUAL-FREQUENCY MODULATION.

Summary form only given. A sensitive optical interferometric technique, dual-frequency modulation (DFM), for measuring and stabilizing a laser frequency by comparison in a single step to a radio-frequency standard is reported. It is designed to provide a tunable source for high-resolution laser spectroscopy whose absolute frequency is known to tens of kilohertz and is stable to several hundred hertz or less. Preliminary measurements give a resolution of 2 parts in 10** minus 10 . The principle of the technique rests on phase locking the mode spacing of an optical cavity to a radio-frequency standard and simultaneously phase locking a laser to the Nth order of the same cavity.