Continuous-wave terahertz imaging with a hybrid system

The authors have developed a hybrid system for coherent raster-scan imaging at 0.6THz. It combines a high-power electronic source (a multiplied Gunn emitter) with a femtosecond Ti:sapphire laser in order to achieve a high dynamic range via electro-optic detection. The single-scan dynamic range of 60db at a lock-in time constant of 10ms is sufficient to permit detection of scattered terahertz radiation in addition to specularly reflected/transmitted light. Active synchronization of the electronic source and the laser is not needed because of the remarkably low jitter between the two radiation sources.