Enhancement of narrow-band terahertz radiation from large aperture photoconductors through multiple pulse excitation

Summary form only given. We present the saturation properties of the THz emission from biased, large aperture photoconductors excited by trains of amplified fs optical pulses. Our studies demonstrate avoidance of saturation effects through multiple pulse excitation, and hence a strong enhancement of the peak power spectral density, for emitters with carrier lifetimes shorter than the interpulse spacing. Such an enhancement was previously observed for photoconductive dipole antennas excited by pulses from a mode-locked oscillator; the current experiments extend this to the much higher THz field regime available using large aperture emitters and amplified laser pulses. Our results also confirm that the saturation recovery time depends on the photocurrent lifetime, consistent with previous theoretical results.