NONLINEAR PHOTOCONDUCTIVITY CHARACTERISTICS OF ANTENNA ACTIVATED BY 80-PICOSECOND OPTICAL PULSES

We report nonlinear characteristics of the radiated field, generated b y a gigahertz photoconducting antenna, versus the bias field. For semi -insulating GaAs a saturation phenomenon was observed when the photoca rrier population was below 3 x 10(16)/cm(3). A set of characteristic c urves was obtained as a function of bias field (< 12 KV/cm) and optica l fluence (< 30 mu J/cm(2)). Fe-doped InP and LTG-GaAs were also inves tigated for comparisons, The experimental data obtained can be qualita tively analyzed by the bias field depletion effect and electron inters ub-band scattering mechanism, This technique can also be utilized as a convenient tool to study the transient electronic: behavior of the ph otocarriers in the picosecond regime.