Backward difference frequency generation in an AlGaAs waveguide

We report on the observation of a noncollinear difference frequency generation at 1.55 mu m in an AlGaAs multilayer waveguide. In such three-wave-mixing process, which occurs between a transverse pump beam and two counterpropagating guided modes, the phase matching parameter is the angle of incidence of the pump and the peak efficiency is 3.5x10(-6) W-1. This innovative device is suitable as a tunable, narrow-bandwidth source of counterpropagating twin photons for quantum information. (c) 2006 American Institute of Physics.