Generation of mid-infrared radiation in a highly absorbing nonlinear medium

We propose a novel scheme for generation of mid-infrared radiation in nonli near waveguides with high absorption in that wavelength range. Coupling the absorbing nonlinear waveguide to a linear waveguide with low absorption al lows the mid-infrared radiation to escape before absorption sets in, thus e nhancing the frequency-conversion efficiency by as much as an order of magn itude. (C) 2001 Optical Society of America.