Evaluation of the CPT pseudo-resonance scheme for all-optical 87Rb frequency standard

We investigate a novel approach to all-optical frequency standards, based on a combination of the coherent population trapping effect and signal discrimination at the maximum of absorption of the probe radiation. The physics underlying this approach is dark resonance splitting caused by interaction of the nuclear magnetic moment with an external magnetic field. Theoretically it has been shown that this approach under ideal conditions can lead to an important enhancement of the clock stability. Here we present an experimental evaluation of the scheme in view its future application in the domain of vapor-cell atomic clocks. The present results point out that high-performances short-term stability can be obtained only with a high spectral quality light source. In contrast, for our compact and low-consumption setup, the shot-noise limited short-term stability calculated is about 10^-12τ^-1/2, which is comparable to those presently measured for typical CPT-based atomic clocks.