Nonresonant Optical Nonlinearities in GaAs/AlGaAs Multiple Quantum Well Waveguides

[摘要] This thesis describes experiments performed to investigate nonlinear absorption and refractive index changes in GaAs/AlGaAs Multiple Quantum Well (MQW) waveguides. Nonlinear transmission experiments were first carried out with a single Nd3+:YAG laser beam at 1.06 mum and, when the experiments were analysed, the TPA coefficient, B, was calculated to be 2.2x10e-10 m W-1 for TM polarisation and 2.7x10-e10 m W-1 for TE polarisation. This analysis to calculate B was done in the usual way of many studies of two-photon absorption (TPA) in semiconductors, that is neglecting the effect of free carrier absorption (FCA). An intuitive theoretical model was derived to include the effect of FCA in the waveguide and when the same nonlinear transmission experiments were analysed using this new model, p was found to be 1.3x10e-10 m W-1 and 2.0x10e-10m W-1 for TM and TE polarisations respectively.

[发布机构] University:University of Glasgow

[关键词] Materials science, Electrical engineering, Condensed matter physics