Applications of velocity selective optical pumping of atomic vapors using pump-probe spectroscopy

Vladimir A. Sautenkov, Sergey A. Saakyan, Andrey A. Bobrov +1 more

Takahisa Mitsui Takahisa Mitsui, Hidetoshi Numata, Katsumi Sakurai

Doppler-free spectroscopy of high density atomic vapor has been demonstrated using copropagating pump-probe selective reflection. The observed narrow resonance has been interpreted theoretically taking account of the saturation of the atomic vapor. Our theory predicts that the saturation effect due to optical pumping is not uniform over the Doppler-broadened transition and is prominent at zero velocity.

Ganghua Mei

Junmin Wang, Qiangbing Liang, Jing Gao +3 more

Two schemes of Doppler-free high-resolution velocity-selective optical-pumping atomic spectroscopy, named single-resonance optical pumping (SROP) and double-resonance optical pumping (DROP), are performed and characterized with room-temperature cesium vapor cells. Due to velocity-selective optical pumping from one hyperfine fold of ground state to another via one-photon excitation in SROP or cascade two-photon excitation in DROP and decay processes thereafter, the atomic population variation of one hyperfine fold of ground state is indicated by SROP and DROP spectra by using of the transmission of the probe laser which is usually frequency locked to a cycling hyperfine transition. As a result, SROP and DROP spectra often have flat background and higher signal-to-noise ratio. Therefore, SROP and DROP spectra are very useful for measurement of the dressed-state splitting of ground state with an alkali atomic vapor cell, precise measurement of hyperfine splitting of alkali atomic excited states, frequency references for laser frequency stabilization, two-color MOT, and so on.

A. M. Akulshin, V. L. Velichanskiǐ, R. Gamidov +3 more

John E. Bjorkholm, P. F. Liao, Alexander J. Wokaun

We have observed that spectral lines obtained in sodium vapor can be strongly distroted when using two-photon spectroscopy with a resonant intermediate state. In some cases, the spectral lines appear to be split into two components. We demonstrate that these effects are due to velocity-selective optical pumping of the atomic ground state; the line shapes reflect the velocity distribution of atoms in the excited intermediate state. We have analyzed the effects using the time-dependent solutions of the rate equations which describe the time evolution of optical pumping for the various atomic velocity groups, and we obtain good agreement with experiment. Optical-pumping problems are often analyzed with the use of steady-state rate equations which incorporate phenomenological relaxation; such approaches are not capable of describing our observations. Velocity-changing collisions are shown to suppress the effects and they explain why these effects were not previously observed; the previous experiments were carried out with slight amounts of a buffer gas in the vapor cell. The effects reported here must be accounted for when carrying out laser-induced line-narrowing experiments in atoms or molecules that can be optically pumped; they can also be used as a new and more sensitive probe of optical pumping in vapors.