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

We report the observation of second-harmonic generation (SHG) in refle ction from a GaAs/AlxGa1-xAs asymmetric quantum-well (AQW) structure a nd a GaAs(001) face. SHG intensities are measured as a function of sam ple azimuthal angle for several polarization configurations using a pu lsed 775-nm fundamental beam. Isotropic contributions to the p-polariz ed SHG intensity are found for both samples, which provides clear evid ence of SHG arising from both the AQW structure and the GaAs(001)/oxid e buried interface. The experimental results are consistent with a str ong SHG contribution from the AQW structure with magnitude close to th at of the bulk contribution; this interpretation is supported by previ ous theoretical predictions. Given the magnitude of the second-harmoni c susceptibility for an AQW, strong SHG enhancement for visible and/or near-infrared light by full implementation of quasi-phase-matching is feasible.