Gain Spectroscopy Of Excitonic Molecules And Its Dynamics In A Znse Single Quantum Well

We demonstrate spectroscopically how optical gain is formed in an interacting system of excitons and biexcitons in a single ZnSe quantum well. The dynamics of gain formation are studied on a subpicosecond time scale in pump-probe experiments, revealing the influence of coherent effects and the impact of exciton-exciton and exciton-biexciton interactions. Spectrally resolved, polarization-dependent degenerate four-wave-mixing experiments further demonstrate how the excitonic many-body phenomena profoundly influence the nonlinear optical response in this II-VI semiconductor heterostructure.