Quantum spatial correlations of optical beams counterpropagating in Kerr media

This study focuses on the case of a system consisting of a Kerr medium of thickness L, within which two beams, with forward (F) and backward (B) amplitudes, counterpropagate. A classical model for this system predicted the existence of a transverse modulational instability (MI) above a suitable threshold of the pump beam intensities. Instabilities of similar nature have been experimentally observed e.g. in sodium or rubidium vapors.