Enhancement of optical pumping efficiency by frequency-modulated lasers

Abstract

Optical pumping of an atomic vapor with low-power lasers often results in low pumping efficiency because of the narrow laser linewidth. Broadening of the laser spectrum by frequency modulation (FM) ensures the contribution of atoms from all velocity classes. We numerically evaluate the difference between the population enhancement for a vapor pumped with a modulated laser and that with a nonmodulated laser. The most efficient modulation scheme among those considered is FM with narrow-band Gaussian noise. The achieved optical pumping enhancement depends on laser linewidth and available power.