Hole-burning in an Autler-Townes doublet and in superluminal (subluminal) Electromagnetically induced transparency of a light pulse via a joint nonlinear coherent Kerr effect and Doppler broadening

摘要

We investigate the behavior of light pulse propagation in a 4-level doubleLambda atomic system under condition of electromagnetically inducedtransparency. The Fano type interference effect and spectral hole burningappears in the the dynamics of the absorption-dispersion spectra caused by thejoint nonlinear coherence Kerr effect and Doppler broadening. The coherent Kerreffect exhibits an enhancement (reduction) in superluminal (subluminal) innegative (in positive) group index while the Doppler broadening generatesmultiple hole burning in the Autler-Townes like spectra of this system. Thehole burning in addition with coherent Kerr effect on the spectral profileinfluences the dynamics of subluminal and superluminal of the probe pulsethrough the medium. The characteristics of superluminality and subluminalitymodified by considering cold-Kerr-free medium and hot-Kerr-dependent mediums.The light pulse delays and advances in different regions of dispersion mediumwith the Doppler broadening and coherent Kerr effect. Consequently, the pulsedelays by $49\mu s$, while advance by $-91\mu s$, for a same set of parameters[note: a revised version is under preparation