Absorption and gain spectra of optically excited semiconductor quantum wires: Effects of Coulomb correlation and screening

We present a systematic study on optical spectra of one-dimensional semiconductor quantum wires by solving the semiconductor Bloch equations. Many-body Coulomb interactions are substantially enhanced by strong geometrical confinement in quantum wire systems. Our theoretical calculation reveals that phase-space filling has strong influence on the absorption spectra. Increasing carrier density bleaches the exciton peak in low-density regime, and induces considerable optical gain in very high density. Band-gap renormalization is partially cancelled by reduction of exciton binding energy, which increases as the cross-section of quantum wire decreases.