Solitons in quadratic nonlinear photonic crystals.
We study solitons in one-dimensional quadratic nonlinear photonic crystals with modulation of both the linear and nonlinear susceptibilities. We derive averaged equations that include induced cubic nonlinearities, which can be defocusing, and we numerically find previously unknown soliton families. Because of these induced cubic terms, solitons still exist even when the effective quadratic nonlinearity vanishes and conventional theory predicts that there can be no soliton. We demonstrate that both bright and dark forms of these solitons can propagate stably.
Periodically switched nonlinear structures for frequency conversion: theory and experimental demonstration
In this paper, we report on the analytical study of a first-order quasi-phase-matched structure based on a periodically switched nonlinearity. The general average equations describing parametric wave interaction for this structure are obtained. The theoretical results are then used to analyze the special case of a device based on a semiconductor Al/sub x/Ga/sub 1-x/As waveguide for efficient frequency doubling in the mid-infrared to the far-infrared range. The necessary conditions to obtain an optimal configuration are discussed in both continuous wave and femtosecond-pulse regimes. Our analysis indicates that the conversion efficiency obtained should significantly exceed the efficiency obtained with a periodically poled lithium niobate crystal at long wavelengths. Finally, we include the preliminary results of the experimental demonstration of a waveguide device based on alternating domains of GaAs and Al/sub 0.4/Ga/sub 0.6/As.
Second-harmonic generation at l=1.6 micro m in AlGaAs/Al2O3 waveguides using birefringence phase matching
We demonstrate phase-matched second-harmonic generation from a λ=1.6 μm pump in a GaAs-based waveguide. Phase matching is obtained by using the form birefringence in an AlGaAs/Al2O3 multilayer obtained by selective wet oxidation.