RESONANT ENHANCEMENT OF PARAMETRIC PROCESSES VIA RADIATIVE INTERFERENCE AND INDUCED COHERENCE

Nonlinear optical parametric processes are studied in a resonantly dri ven multilevel system displaying quantum interference effects. It is s hown that in such systems a new regime of nonlinear amplification is p ossible, in which a pair of correlated Stokes and anti-Stokes fields c an be generated from infinitesimally small initial values. An atomic c oherence grating emerges during this process of efficient nonlinear am plification. The present analysis explains the results of recent optic al phase conjugation experiments involving atomic phase coherence. [S0 031-9007(98)01176-2].