OPTICAL FREQUENCY SHIFTERS BASED ON CASCADED 2ND-ORDER NONLINEAR PROCESSES

We propose a novel scheme for an optical frequency shifter that exploi ts cascaded second-order nonlinearity in a semiconductor material. The cascade comprises a sum-frequency interaction followed by a differenc e-frequency conversion in a coupled waveguide-to-vertical-cavity struc ture. For a 50-mu m-long planar waveguide, efficient conversion is sup ported over an effective -3-dB bandwidth of 39 nm at a pump power dens ity of 3.3 W/mu m. A longitudinal in-plane cavity can reduce the requi red pump power density so that effective conversion occurs over a band width of 20 nm at a pump power density of 6 mW/mu m. (C) 1996 Optical Society of America.