Anisotropic homogeneous linewidth of the heavy-hole exciton in (110)-oriented GaAs quantum wells

The homogeneous and inhomogeneous linewidths of the heavy-hole exciton resonance in a (110)-oriented GaAs multiple-quantum-well sample are measured using optical two-dimensional Fourier transform spectroscopy. By probing the optical nonlinear response for polarization along the in-plane crystal axes [1 (1) over bar0] and [001], we measure different homogeneous linewidths for the two orthogonal directions. This difference is found to be due to anisotropic excitation-induced dephasing, caused by a crystal-axis-dependent absorption coefficient. The extrapolated zero-excitation density homogeneous linewidth exhibits an activation-like temperature dependence. We find that the homogeneous linewidth extrapolated to zero excitation density and temperature is similar to 34 mu eV, while the inhomogeneous linewidth is similar to 1.9 meV for both polarizations.