Three-photon-absorption resonance for all-optical atomic clocks

Abstract

We report an experimental study of an all-optical three-photon-absorption resonance (known as an ``$N$ resonance'') and discuss its potential application as an alternative to atomic clocks based on coherent population trapping. We present measurements of the $N$-resonance contrast, width and light shift for the ${D}_{1}$ line of $^{87}\mathrm{Rb}$ with varying buffer gases, and find good agreement with an analytical model of this resonance. The results suggest that $N$ resonances are promising for atomic clock applications.