EXCITONIC OPTICAL BISTABILITY IN N-TYPE-DOPED SEMICONDUCTORS

A resonant monochromatic pump laser generates coherent excitons in an n-type-doped semiconductor. Both exciton-exciton and exciton-donor int eractions come into play. The former interaction can give rise to the appearance of optical bistability. which is heavily influenced by the latter one. When optical bistability occurs at a fixed laser frequency both its holding intensity and hysteresis-loop size are shown to decr ease with increasing donor concentration. Two possibilities are sugges ted for experimentally determinng one of the two parameters of the sys tem. the exciton-donor coupling constant or the donor concentration if the other is known.