Many-Body Renormalization of Semiconductor Quantum Wire Excitons: Absorption, Gain, Binding, Unbinding, and Mott Transition

We consider theoretically the formation and stability of quasi-one dimensional many-body excitons in GaAs quantum wire structures under external photoexcitation conditions by solving the dynamically screened Bethe-Salpeter equation for realistic Coulomb interaction. In agreement with several recent experimental findings the calculated excitonic peak shows very weak carrier density dependence upto (and even above) the Mott transition density, $n_c\sim 3\times {10}^5$ cm${}^{-1}$. Above $n_c$ we find considerable optical gain demonstrating compellingly the possibility of one-dimensional quantum wire laser operation.