Temperature Dependence of Dark Lines in Coherent PopulationTrapping

Abstract

We measure the signal amplitude and linewidth of a dark line incoherent population trapping in the Rb vapour cell filled withmixed buffer gas N2 and Ar as a function of cell temperature. Wefind that the dark line signal amplitude increases with temperature upto a maximum at 49°C and then drops at higher temperatures due toquenching effects of N2. The linewidth of the dark line remainsbasically constant, at 1080 Hz. We also measure the linewidth of the darkline as a function of laser intensity. The linewidth increases linearlywith laser intensity. An intrinsic linewidth (FWHM=896 Hz at 3.4 GHz) ofthe Rb cell is obtained.