We report the study of optically induced terahertz (THz) electromagnet
ic radiation from [110] oriented zinc-blende crystals. This work exten
ds our previous studies of [100] and [111] GaAs. Excellent agreement b
etween calculated results and experimental data indicates that, under
conditions of moderate optical fluence and normal incidence on the unb
iased sample, second-order optical rectification is the major nonlinea
r process that generates THz radiation.