Broadband efficient nonlinear difference generation in a counterpropagating configuration

A counterpropagating parametric nonlinear interaction is considered in the framework of a short one-dimensional photonic crystal. This interaction, otherwise highly inefficient, is shown to be efficient in the framework of such one-dimensional photonic crystal. The large momentum mismatch of this counterpropagating interaction is shown to be compensated for a broad range of frequencies when difference generation is considered. The numerical results presented indicate that such nonlinear photonic crystals are a very good material to consider the observation of backward parametric oscillation without mirror feedback.