Photoconductive antennas with nano-structured electrodes and which show significantly improved performances have been proposed to satisfy the demand for compact and efficient terahertz (THz) sources. Plasmonic field enhancement was previously considered the dominant mechanism accounting for the improvements in the underlying physics. However, we discovered that the role of plasmonic field enhan...

We present a planar large-area photoconducting emitter for impulsive generation of terahertz sTHzd radiation. The device consists of an interdigitated electrode metal-semiconductor-metal sMSMd structure which is masked by a second metallization layer isolated from the MSM electrodes. The second layer blocks optical excitation in every second period of the MSM finger structure. Hence charge carr...

Widely tunable, Fourier-transform-limited pulses of terahertz (THz) radiation have been generated using (i) crystals of the highly nonlinear organic salt 4-N ,N -dimethylamino-4-N -methyl stilbazolium tosylate (DAST), (ii) zinc telluride (ZnTe) crystals, (iii) gallium phosphide (GaP) crystals, and (iv) low-temperature-grown gallium arsenide (LTG-GaAs) photomixers with THz spiral antennas. Outpu...

The study of carrier multiplication has become an essential part of many-body physics and materials science as this multiplication directly affects nonlinear transport phenomena, and has a key role in designing efficient solar cells and electroluminescent emitters and highly sensitive photon detectors. Here we show that a 1-MVcm(-1) electric field of a terahertz pulse, unlike a DC bias, can gen...

The interest in surface terahertz emitters lies in their extremely thin active region, typically hundreds of atomic layers, and the agile surface scalability. The ultimate limit in the achievable emission is determined by the saturation of the several different mechanisms concurring to the THz frequency conversion. Although there is a very prolific debate about the contribution of each process,...

We describe the use of mixing linearly chirped optical pulses in biased photoconductors to generate tunable narrow-band terahertz (THz) radiation with enhanced spectral brightness. The increase in conversion efficiency from optical to THz radiation at a given THz frequency arises from the improved saturation characteristics of the photoconductor for chirped-pulse mixing compared with the usual ...