Observation of ultrashort pulse propagation anisotropy in a semiconductor quantum nanostructure optical waveguide by cross-correlation frequency resolved optical gating spectroscopy

Femtosecond optical pulse propagation in a quantum well (QW) waveguide and a quantum wire (QWR) waveguide was investigated by cross-correlation frequency resolved optical gating (XFROG) spectroscopy. An optical pulse transmitted through the GaAs QW waveguide was found to stretch greatly from 140 fs to almost 1 ps due to nonlinear dispersion around the heavy hole exciton resonance at transverse electric polarization in a near resonant experiment. In contrast, only slight chirping of the pulse transmitted was observed either at transverse magnetic polarization or off resonance for both polarizations. In the GaAs QWR waveguide, the polarization anisotropy of a crescent shaped QWR could also be observed in terms of dispersion by XFROG spectroscopy in spite of the small absorption compared with that in the QW. (C) 2003 American Institute of Physics.