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.
Highly efficient direct third-harmonic generation based on control of the electro-optic effect in quasi-periodic optical superlattices.
We present a method for controlling the efficiency of direct third-harmonic generation in quasi-periodic optical superlattices by means of the electro-optic effect. The calculated results manifest that this method is extremely efficient for achieving high efficiency of direct third-harmonic generation in predesigned quasi-phase-matched coupled parametric processes and is feasible at any given fundamental intensity. In addition, we demonstrate that the electro-optic control approach is significantly better than the temperature-control method.
Modulation of the second-order susceptibility in GaAs/AlAs superlattices
The modulation of the bulk-like second-order susceptibility with quantum well disordering is calculated for a GaAs/AlAs superlattice. The calculation is based on the A⋅p form of the susceptibility, which is the more appropriate form for semiconductors, and includes the influence of the Γ15c upper conduction band set which ensures the necessary absence of inversion symmetry. The undisordered structure has the degeneracy broken between the χxyz(2) and χzxy(2) tensor elements which is restored upon disordering. The shift of the half-band gap resonance gives a maximum modulation depth Δχxyz(2)≈60 pm V−1 in the transparency window for this structure.