Transient Optical Spectra of a Dense Exciton Gas in a Direct-Gap Semiconductor

摘要: The observation is reported of a remarkable persistence the $1s$ exciton resonance in transient picosecond absorption spectra GaAs under conditions resonant optical excitation up to pair densities two orders magnitude above Mott density. stability (excess linewidth 0.8 meV at $n=6\ifmmode\times\else\texttimes\fi{}{10}^{16}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) this dense gas against decay into energetically more favorable continuum electron-hole pairs due relatively weak self-screening discrete excitons.