Abstract

Optical nonlinearities arising due to photogenerated carrier transport lead to internal space-charge electric fields which, in turn, modulate the optical properties of materials. High mobility of electrons together with the applied electric field provide much faster material response time of compound semiconductors (as GaAs, InP, CdTe) in comparison with the conventional photorefractive materials. In addition, a strong external field may introduce essentially new features of electrooptic nonlinearity due to intervalley transfer of electrons in multi-valley semiconductors. Due to a negative differential mobility μ_d = dv/dE <0 of hot carriers, the space charge fluctuations are not screened but grow because of a negative dielectric relaxation time τ_md =εε_o/(eμ_dn) <0 in a region of a negative differential resistance.

© 1998 IEEE