arXiv:1405.7477 · Journal of the Optical Society of America B
Velocity selective bipolarization spectroscopy for laser cooling of metastable krypton atoms
Y. B. Kale, Vibhuti Bhushan Tiwari, Sunita Singh, Satya Ram Mishra, H. S. Rawat
Abstract
We report a velocity selective bipolarization spectroscopy (VS-BPS) technique to generate a background-free, dispersion-like reference signal which is tunable over a wide range of frequency. In this technique, a pair of linearly polarized weak probe beams passing through a gas cell of metastable krypton (Kr*) atoms overlaps with a pair of counterpropagating circularly polarized strong pump beams derived from an independently tunable control laser. The polarization spectroscopy signals from the two probe beams, after subtraction, result in the VS-BPS signal. The spectral shifting in the VS-BPS signal can be achieved by tuning the frequency of the control laser. The dependence of the amplitude and slope of the VS-BPS signal on the RF power used for excitation of Kr atoms in the gas cell and on the power of pump beams has been studied. The frequency stability of a diode laser locked with VS-BPS signal has been found to be better than the frequency stability of the laser locked with a saturated absorption spectroscopy signal. The VS-BPS signal is finally used for stabilization and tuning of the cooling laser frequency for a magneto-optical trap for Kr* atoms.