Emission detection of dark resonance in a dilute lithium atomic vapor

Abstract

Dark resonance in coherent population trapping of lithium atoms in the ground state is measured by detecting atomic light emission. Compared to transmission detection, emission detection improves the signal-to-noise ratio of the resonance signal at low temperatures, extending the lower temperature limit to 220 ∘ C . This corresponds to an atomic density, 1 order of magnitude smaller than the saturated density required in transmission detection. In Ar gas, the resonance width at a low temperature is found to be decreased to 45 Hz, which is as narrow as in He and Ne gases.