Dithered-edge sampling of terahertz pulses: fast detection using slow photoconductive receivers

Abstract

We introduce dithered-edge sampling (DES) as a new technique for ultra-wideband measurement of terahertz pulses using photoconductive antennas. The terahertz pulse is sampled by first passing it through a photoconductive gate whose fast attenuation edge (limited only by the duration of the optical gating pulse) is dithered in time. A slow photoconductive receiver then measures the component of the terahertz electric field that is modulated at the dither frequency. When used alone, the receiver blurs the measured terahertz pulse width to 1.3 ps. However, the increased time resolution of the DES system (gate + receiver) allows one to measure source-limited terahertz pulse widths (400-fs in this case) [D.You et. al, Opt. Lett. 18, 290 (1993)]. In addition, we have used the DES technique to make what we believe to be the first direct measurement of a photoconductive receiver’s temporal response.KeywordsOptical PulsePulse Electric FieldTerahertz PulsePhotoconductive AntennaAntenna GeometryThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.