Transverse modulational instabilities for counterpropagating beams in Kerr media

Abstract

Continuous-wave and oscillatory transverse instabilities are predicted for counterpropagating waves in Kerr media for both focusing and defocusing nonlinearities. Neither a cavity nor a finite response time is required. Computed Gaussian-beam results agree well with analytic plane-wave calculations that straddle Raman-Nath and Bragg regimes.