NONLINEAR OPTICS AND PLASMA-INDUCED BISTABILITY IN CDS

The investigation of highly excited semiconductors and of nonlinear optical properties recently tends to merge into one field of semiconductor physics. This is demonstrated for the case of CdS. Two experimental methods are presented, which allow us both to detect optical nonlinearities and to understand their physical origins. These are the creation of laser-induced gratings and the excite- and-probe technique. The reasons for the nonlinearities are a broadening of the exciton resonances, transitions to the biexciton and the formation of an electron-hole plasma. The latter point is discussed in some detail and it is demonstrated, how the nonlinearities connected with this phase transition may be exploited to produce a dispersive and an intrinsic, absorptive bistability.