Analytical Expressions of the Dark Resonance Parameters in a Vacuum Vapor Cell

This article reports a dedicated theoretical and experimental study on the properties (signal amplitude, linewidth) of coherent population trapping (CPT) resonances detected in vacuum vapor cells. Results are presented for conventional singlelambda schemes of atomic energy levels but also for doublelambda schemes, now widely used in various applications including atomic clocks and magnetometers. Approximate compact analytical expressions, valid for a wide range of light wave intensities, i.e. beyond the low intensities or pump-probe regime, have been obtained. Analytical results are found to be in excellent agreement with exact numerical solutions based on the optical Bloch equations. Experimental results, obtained in a Cs vapor microfabricated cell, are reported and found to be in correct agreement with theoretical expressions.