Femtosecond near-field spectroscopy of a single GaAs quantum wire

Quasi-two-color femtosecond pump and probe spectroscopy and near-field scanning optical microscopy are combined to study the carrier dynamics in single semiconductor nanostructures. In temporally, spectrally, and spatially resolved measurements with a time resolution of 200 fs and a spatial resolution of 200 nm, the nonlinear change in reflectivity of a single quantum wire is mapped in real space and time. The experiments show that carrier relaxation in a single quantum wire occurs on a 100 fs time scale at room temperature. (C) 1999 American Institute of Physics. [S0003-6951(99)05148-7].