Large-area high-power THz emitter based on interdigitated electrodes

We present a planar large-area photoconductor based on GaAs for impulsive generation of THz radiation. The device consists of an interdigitated electrode metal-semiconductor-metal structure (MSM) with 5 µm electrode spacing. The MSM structure is masked by an opaque metallization layer isolated from the MSM electrodes in a way that optical excitation takes place only in regions with unidirectional electric field. Constructive interference of the THz emission from accelerated carriers leads to amplitudes that are 10⁴ times higher than from the same MSM structure without second metallization layer.