A terahertz emitter based on the lateral photo-Dember effect is shown to efficiently generateterahertz radiation with a peak frequency of 0.7 THz and an electric field amplitude up to 5 V/cm when excited by 90 fs pulses centered at 1.55 μm. A thin layer of In0.53Ga0.47As grown on InP provides the substrate material in which unidirectional lateral photo-Dember currents are excited. Since photo-Dember terahertz emitters do not require an external bias, they do not suffer from high dark currents limiting the application of biased InGaAs photoconductive terahertz emitters.