Velocity Selective Polarization Spectroscopy for Modulation-Free Dispersion Signals at Detuned Frequencies

Abstract

We present a simple technique to obtain modulation-free locking signals at the detuned frequency from an atom transition between hyperfine structures. Polarization spectroscopy allows us to obtain the dispersion signals that are suitable for frequency locking. Velocity selective optical pumping using another laser beam also allows us to obtain signals at the detuned frequency and to shift crossover signal away. By combining these two techniques, we were able to obtain the velocity selective birefringence signal only at the principle transition in an Rb vapor cell and compare the birefringence signal with the theoretical spectrum predicted by using Nakayama’s model.

Velocity selection in a Doppler-broadened ensemble of atoms interacting with a monochromatic laser beam

“…Later, more involved models of polarization spectroscopy were developed, emphasizing the importance of a careful treatment of the effects of atomic velocity (13 -15 ). Velocity-selective polarization spectroscopy remains an active topic in atomic (16 ) and molecular physics (17 ); the importance of Doppler averaging in calculating the medium's response in pump-probe laser spectroscopy is well known (18 ).…”