Resonant four-wave interaction in the field of pump waves of arbitrary intensity

A theoretical investigation is made of the influence of the asymmetry of the intensities of pump waves on the spectrum of weak radiation participating in a nondegenerate four-wave interaction in a resonant medium with a homogeneously broadened absorption line. It is shown that a difference between the intensities of pump waves results in additional modulation of the spectrum of reflected and transmitted waves. In particular, an increase in the asymmetry of the pump wave intensities increases the phase mismatch between the waves and reduces the central maximum in the weak radiation spectrum. When the difference between the intensities of the pump waves becomes sufficiently large, this central maximum of the reflected radiation disappears completely and the side maxima acquire a doublet structure. It is shown that the position of the maxima in the reflected radiation spectrum corresponds exactly to the minima of the phase matching between the waves. An analysis is made of the characteristics of a reflecting narrow-band optical filter based on a nondegenerate four-wave interaction in a resonant medium.