Sub-natural linewidth in room-temperature Rb vapor using a control laser

Rapol, Umakant D.; Wasan, Ajay; Natarajan, Vasant

Sub-natural linewidth in room-temperature Rb vapor using a control laser

Authors

Rapol, Umakant D.

Wasan, Ajay

Natarajan, Vasant

Description

We demonstrate two ways of obtaining sub-natural linewidth for probe absorption through room-temperature Rb vapor. Both techniques use a control laser that drives the transition from a different ground state. The coherent drive splits the excited state into two dressed states (Autler-Townes doublet), which have asymmetric linewidths when the control laser is detuned from resonance. In the first technique, the laser has a large detuning of 1.18 GHz to reduce the linewidth to 5.1 MHz from the Doppler width of 560 MHz. In the second technique, we use a counter-propagating pump beam to eliminate the first-order Doppler effect. The unperturbed probe linewidth is about 13 MHz, which is reduced below 3 MHz (0.5 Γ) at a detuning of 11.5 MHz.
4 pages, 7 figures