Dynamics of electric field screening in photoconductive THz sources with spatially patterned excitation

We show that the effects of photoinduced screening of the bias field as a function of optical spot shape for ultrafast excitation of photoconductors to generate terahertz radiation using spatially resolve Monte Carlo simulations coupled with a self-consistent Poisson solver. The results of the simulations demonstrate that given the same photoexcited carrier density, a line focus parallel to the direction of the bias field suppresses saturation at high optical fluence due to space-charge screening and enhances the peak terahertz power in the time domain