A multi-factor model for the coherent population trapping resonance

A systematic semi-analytical study of the coherent population trapping resonance is presented. The emphasis is put on quantifying the importance of different experimental factors potentially affecting the shape of the resonance, and especially the magnitude and structure of the light shift. In particular, we consider the impact of FM modulation, spectrum asymmetry, light detuning, and an optically thick atomic medium. The proposed model allows for a quick and reliable check whether a zero light shift can be reached in a realistic experimental setting. The results of modeling are compared with the experiment carried out with a diode laser (vertical-cavity surface emitting laser) and 87Rb atoms.