Optimization of the experimental parameters of cesium CPT system

Based on a Λ-type three-level system consists of cesium (Cs) 6S 1/2 (Fg = 3) and 6S1/2 (Fg = 4) long-lived ground states and 6P 3/2 (Fe = 4) excited state, we have experimentally measured and theoretically analyzed the characters of coherent population trapping (CPT) resonances in Cs vapor cells with different partial pressure of neon (Ne) as buffer gas around room temperature. The impact of some experimental parameters, such as the relative intensity ratio between two phase-locked laser beams, the laser intensity, with or without buffer gas and the partial pressure of Ne, the temperature and the longitudinal magnetic field, on the CPT resonance was studied in details. With the optimized parameters, we got typical CPT signal with the full-width half-maximum (FWHM) linewidth as narrow as ~ 181 Hz in a Cs vapor cell filled with 30 Torr of Ne as buffer gas.