Sub-Doppler resolution controlled by two coherent driving fields

Abstract

A four-level model is proposed where sub-Doppler resolution, enhanced absorption and transparency windows for a weak probe field are manipulated by using two coherent driving fields in the way that is not possible in three-level schemes. We show how an interplay of quantum coherence and interference effects induced by two driving fields allows one to concurrently couple molecules from a wide velocity interval to a probe radiation and consequently to enhance cross-section of optical processes in Doppler-broadened media.