A method and device for generating terahertz radiation comprising a substrate; a plurality of segments of polar crystal material formed on the substrate, the segments having an internal electric polarization; each segment comprising at least two edges oriented substantially perpendicular to the polar axis such that the electric polarization terminates at the edges and the segment comprises a majority of positive charges on one edge and a majority of negative charges on the opposite edge thereby leading to creation of an internal electric field; whereby when irradiated by a pulsed source of duration less than one picosecond, electron-hole pairs are generated within the segments and the internal electric field separates and accelerates the electron-hole pairs to thereby produce terahertz radiation.