2ND-HARMONIC GENERATION FROM A GAAS/AL1-XGAXAS ASYMMETRIC QUANTUM-WELL STRUCTURE

We report the observation of second-harmonic generation (SHG) in reflection from a GaAs/AlxGa1-xAs asymmetric quantum-well (AQW) structure and a GaAs(001) face. SHG intensities are measured as a function of sample azimuthal angle for several polarization configurations using a pulsed 775-nm fundamental beam. Isotropic contributions to the p-polarized SHG intensity are found for both samples, which provides clear evidence of SHG arising from both the AQW structure and the GaAs(001)/oxide buried interface. The experimental results are consistent with a strong SHG contribution from the AQW structure with magnitude close to that of the bulk contribution; this interpretation is supported by previous theoretical predictions. Given the magnitude of the second-harmonic susceptibility for an AQW, strong SHG enhancement for visible and/or near-infrared light by full implementation of quasi-phase-matching is feasible.