All-Optical Atomic Clock Based on Coherent Population Trapping in 85Rb.

摘要

An all-optical RF-frequency standard based on coherent population trapping (CPT) in (sup 85)Rb has been developed. The CPT resonances are detected using an ordinary edge-emitting diode laser in a simple optical set-up. A buffer gas mixture has been carefully optimized to yield narrow resonances and reduced temperature dependence of the resonance frequency. With the developed system the authors have been able to measure ultra-narrow optically induced hyperfine CPT resonances below 20 Hz, apparently the narrowest ever measured and in good agreement with the linewidth calculated from the experimental parameters. The frequency of an RF-signal generator has been stabilized to the CPT resonance between the m(sub F)=0 magnetic sublevels.