Electro-optic detection of continuous wave terahertz radiation

Summary form only given. The ability to generate CW coherent terahertz (THz) radiation using CW laser light has stimulated significant interest in recent years. An attractive feature of this approach is the ability to create an inexpensive, compact, narrow linewidth source capable of high-resolution spectroscopy in the far-infrared. CW THz radiation generated from photomixers is typically detected with bolometers. While this approach has proved to be very effective, one must operate bolometers at cryogenic temperatures in order to reduce detection noise. Furthermore, bolometers are square-law detectors, which lose all information about the phase of the THz electric field. Thus, it would be advantageous to develop room-temperature coherent detection techniques. We demonstrate the application of free-space electro-optic detection as an attractive alternate approach for the coherent detection of CW THz radiation. In contrast to time-domain sampling, where noise suppression is achieved by the short "gating" time of the receiver, the detection technique demonstrated is a frequency domain measurement technique that relies on coherent upconversion of the THz field combined with optical homodyne detection for noise suppression.