Dynamics of instantaneous frequency and amplitude of coherent wave mixing in quantum confined semiconductor structures

In the last fifteen years, quantum confined semiconductor structures (QCSS) have attracted much attention because of their novel properties and their potential for electronic and photonic applications. Electronic and optical properties of QCSS are dominated by the combined effects of quantum statistics and Coulomb interaction. Their response to electromagnetic excitations is determined by a polarization which possesses a time dependent amplitude and phase. Although the phase is a very sensitive probe of microscopic scattering and collision mechanisms, most of ultrafast spectroscopy of heterostructures has concentrated on measuring the amplitude only. Using a combination of time-resolved, frequency-resolved, and interferometric correlation techniques the author has recently investigated the phase and amplitude of coherent wave mixing (CWM) emission from quantum well structures excited by two ultrashort pulses