Efficient, stable optical pumping of a collimated beam of Ar((3)P(2)) metastable atoms is obtained using a low-power, frequency-modulated multimode dye laser. The advantages provided by frequency modulation are discussed. The technique is suitable for use in optically pumping a wide variety of atomic species.
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.