OPTICAL FREQUENCY CONVERSIONS IN NONLINEAR MEDIUM WITH PERIODICALLY MODULATED LINEAR AND NONLINEAR-OPTICAL PARAMETERS

A new method considering both linear and nonlinear optical parameter modulation and propagation loss is proposed to treat second-order nonlinear optical interactions in nonlinear media having periodic structures, Mathematical expressions are derived for difference frequency generation (DFG) and compared with those for second-harmonic generation (SHG). Wavelength conversions around 1.55 mu m, which are very interesting in optical communication systems, are studied for semiconductor DFG devices with periodic: structures, Semiconductor (e,g,, AlGaAs) DFG devices of standard device lengths (several mm) and pump light intensities (10(5) kW/cm(2)) are shown capable of practical level conversion efficiencies (similar to 10%) and extremely wide bandwidths (greater than or equal to 100 nm). Effects of propagation loss in DFG devices are also examined.