Optics Letters
High-contrast coherent population trapping resonances using four-wave mixing in ^87Rb
Vishal Shah, Svenja A. Knappe, Leo W. Hollberg, John E. Kitching
Abstract
We demonstrate very high-contrast coherent population trapping(1) (CPT) resonances by using four-wave mixing in (87)Rb atoms. In the experiment, we take advantage of the spectral overlap between F=2-->F(?) and F=3-->F(?) optical resonances on the D1 line of (87)Rb and (85)Rb atoms, respectively, to eliminate the DC-light background from the CPT resonance signal. We observe a CPT resonance with a contrast in the range of 90%, compared with a few percent achieved by alternative methods.