Intermixed Superlattices

摘要： The enhancement of stimulated Raman scattering (SRS) with a GaAs/AlAs intermixed superlattice that works as a χ (3)-quasi-phase-matched structure is studied, where such Kerr-induced effects as four-wave mixing (FWM), self-phase-modulation (SPM), cross-phase-modulation (XPM), and two-photon absorption (TPA) are included. In particular, the efficiency of anti-Stokes generation is enhanced here; anti-Stokes generation inherently has an extremely small efficiency due to a phase mismatch in the interaction of the pump, Stokes, and anti-Stokes waves (while the efficiency of Stokes generation is sufficiently large because of no such phase mismatch). The superlattice enhances the anti-Stokes efficiency up to the order of 103 when compared with that without the superlattice, particularly at a small pump intensity. In this enhancement, it is seen that there is an efficiency boost via simultaneous FWM. In this situation, it is shown how much SPM and XPM degrade the efficiency enhancement. Furthermore, an optimal superlattice length is identified that provides the highest efficiency. The degradation of the efficiency at the optimized length due to TPA is also analyzed. Finally, to gain more anti-Stokes efficiency (or control the sizes of the Stokes and anti-Stokes efficiencies), a photonic-band-gap cavity structure is proposed.