Femtosecond near-field spectroscopy of a single GaAs quantum wire

Quasi-two-color femtosecond pump and probe spectroscopy and near-field scan ning optical microscopy are combined to study the carrier dynamics in singl e semiconductor nanostructures. In temporally, spectrally, and spatially re solved measurements with a time resolution of 200 fs and a spatial resoluti on 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 relaxa tion in a single quantum wire occurs on a 100 fs time scale at room tempera ture. (C) 1999 American Institute of Physics. [S0003-6951(99)05148-7].