Time-domain Equivalent Circuits for the Link Modelling Between Pulsed Photoconductive Sources and Receivers

Photoconductive antennas (PCAs) are promising candidates for sensing and imaging applications. In recent years, our group has investigated their properties under pulsed laser illumination in transmission using a time-domain (TD) Norton equivalent circuit. Here we extend this analysis to the link between a PC source and a receiver introducing for the latter a second TD Norton equivalent circuit. We also evaluate the transfer function of a dispersive quasi-optical (QO) link. Specifically, a field correlation approach based on high-frequency techniques is used to evaluate the spectral transfer function between two bow-tie based PCAs including the QO link. The detected currents in the receiving circuit are reconstructed using stroboscopic sampling of the modelled THz pulses, equivalent to what is actually performed by THz TD systems. Both the amplitude and the waveforms of these currents are evaluated. The QO link is then experimentally characterized to validate the proposed methodology. The comparison between the simulations and the measurements is excellent.