Abstract

Recently it was predicted, and shown experimentally, that a cw coherently induced transparency feature could be observed in a Doppler-broadened cascade medium even when the probe and coupling fields had a wavelength mismatch of several hundred nanometers.¹ This observation is significant since it removes the requirement for finding wavelength-matched systems to carry out cw atomic coherence experiments within an inhomogeneously broadened medium.^2,3 The explanation of this transparency lies with the fact that both E.I.T. and Autler-Townes splitting⁴ are velocity group dependent. Each velocity group experiences its own Doppler-shift and hence detuning from the probe and coupling field transitions. Therefore, there exists a variation in the frequency position of maximum E.I.T. and of the Autler-Townes split components for each velocity groups. It is the integration of both of these effects over all of the velocity groups that produces the overall probe absorption.

© 1997 Optical Society of America