Simulation of fluence-dependent photocurrent in terahertz photoconductive receivers

Abstract

A semi-classical Monte Carlo simulation of carrier dynamics in photoconductive detectors of terahertz (THz) radiation is presented. We have used this simulation to elucidate the importance of carrier trapping in the operation of photoconductive detectors. Simulations of the detection of single-cycle THz pulses by photoconductive antennas based on GaAs with trap densities between 2 × 10 17 and 2 × 10 18 cm −3 are presented. We show that the high frequency (>1 THz) spectral response of photoconductive devices decreases with increasing excitation fluence. Our simulations reveal that this effect is a direct consequence of the saturation of trapping centres

Dynamic Tuning of Mean Carrier Momentum Relaxation Time in InGaAs–InAlAs THz Photoconductive Switches

“…Scattering is supposed to increase due to the excitation of LO-phonons and a higher carrier density [14,23]. Hereby the former make the major contribution, since Monte Carlo-simulations have shown that carrier-to-carrierscattering plays only a minor role, being of elastic nature and thus only causing slight angular deviations of carrier trajectories [24]. Whereas a rise of pulsed optical power merely results in an increase of involved carriers, CW-excited carrier contribution is negligible.…”

Time-domain numerical modeling of terahertz receivers based on photoconductive antennas

“…Finally, the boundary conditions are described in [20] with the Eqs. (23) and (24). Taking into consideration all these contributions, we can calculate the flowing through the metal contacts on the surface S Ω by means of the following equation [shown in Fig.…”

“…The PCA emission has been already studied [14][15][16][17][18][19][20]. There are numerical and experimental studies of receivers based on PCAs [19,[21][22][23][24]; however, as far as we know, the lack of simultaneously simple and accurate numerical methods to simulate reception processes is one of the issues of major concern in THz-TDS and THz-I studies. That is what we do here; for the development of the numerical method presented we have dealt with the usual trade-off, simplicity versus accuracy, in order to address a realistic description of a receiver within a feasible and reasonable numerical approach.…”

“…We do so after demonstrating that both PCA components can be neglected in detection processes with normal incidence of the radiated field. This latter result is important for the development of a simulation tool to study, in direct sampling detection [22,24], the signal-to-noise ratio (SNR) with a particularly simple computational domain [see Fig. 1(d)] in a realistic manner.…”

Fiber-based Terahertz Time-Domain Spectroscopy Systems Operated in the Telecom Band

“…Scattering is supposed to increase due to the excitation of longitudinal optical (LO)-phonons and a higher carrier density [137,148]. Hereby the former make the major contribution, since Monte Carlo-simulations have shown that carrier-to-carrierscattering plays only a minor role, being of elastic nature and thus only causing slight angular deviations of carrier trajectories [149]. Whereas a rise of pulsed optical power merely results in an increase of involved carriers, CW-excited carrier contribution is negligible.…”