Asymmetric half-cycle THz pulses with large ponderomotive potential generated from photoconductive antennas

We report the generation of asymmetric quasi-half-cycle THz pulses with an energy up to 8.3 J generated from a ZnSe interdigitated Large Aperture Photoconductive Antenna (ILAPCA). The THz peak electric field is 331 kV/cm with a spectrum characterized by a median frequency of 0.28 THz, resulting in ponderomotive energy of 15 eV. We observed that the large capacitance of the LAPCA leads to a decrease in and distortion of the biasing voltage pulse, limiting the energy of the THz pulses. The demonstration of the advantages of this source is made with the observation of significant absorption bleaching on n-doped InGaAs.