Opto-Electronic Oscillator Stabilized by a Hyperfine Atomic Transition

摘要

Opto-electronic oscillator (OEO) is a closed-loop system with gain, in which part of the loop is implemented by an optical beam, and the rest by RF circuitry. The technological advantage of this approach over traditional all-RF loops in the gigahertz range comes from the fact that frequency filtering can be done far more efficiently in the optical range with respect to the RF modulation, than in the RF range. As a result, OEO can be made very compact, low power, and have superior stability. In this work, we report our preliminary results on using the phenomenon of coherent population trapping in (87) Rb vapor as an optical filter. Such a filter allows us to stabilize the OEO at the hyperfine splitting frequency of rubidium, thus implementing a novel type of frequency standard.