In nonlinear atomic gaseous media the interference between independent macroscopic polarizations of different ensembles within the atomic velocity distribution can lead to anomalous behavior of the multiwave mixing spectra. For phase-conjugate six-wave mixing (SWM) in a Doppler-broadened N-type four-level system, it is found that the SWM spectrum can be either Doppler-free or very broad, depending on the directions of the incident beams and the ratios between the magnitudes of the wave vectors. This polarization interference can be controlled by the strong coupling field which, on the other hand, can induce Autler–Townes (AT) splitting when the SWM spectrum is Doppler-free. This technique may find special applications as an improved form of AT spectroscopy with higher resolution.
© 2009 Optical Society of America
Original Manuscript: August 3, 2009
Manuscript Accepted: August 31, 2009
Published: November 9, 2009
Jinyan Niu, Ruquan Wang, Ling-An Wu, and Panming Fu, "Polarization interference in six-wave mixing in a Doppler-broadened N-type four-level system," J. Opt. Soc. Am. B 26, 2268-2274 (2009)