Grant: Idea to Innovation

The current proposal aims to improve and thus increase the value of a new invention developed at the INRS for detecting terahertz (THz) radiation, based on spectral domain interferometry (SDI). THz sources and detectors have many important potential applications in the areas of spectroscopy, detection, and security. For example, the low energy photons of THz radiation can be safely used on humans for security purposes at airports, to detect weapons and explosives. THz radiation can also be used to study the vibrational modes of several biological and chemical molecules, since these modes have energies corresponding to THz photon energies.Various methods have been proposed and demonstrated in order to measure the spatial and temporal profile of the THz electric field. Among these, the EO sampling method is widely used for THz time-domain spectroscopy (THz-TDS), due to the relatively straightforward physics involved and its wide bandwidth. However, the EO method suffers from several drawbacks.The advantage of our invention on the SDI method for THz detection is multifold. The present method and system simplifies the required equipment by eliminating complicated components, such as lock-in amplifiers, thus making possible THz detectors that are low-cost and compact. The use of SDI in EO sampling eliminates the need for cross polarizers, thus resulting in extremely high dynamic range, 18,000 times higher than that with conventional methods. This also allows one to overcome the limitation of over-rotation for intense THz electric field detections. By solving the problem of over-rotation for recently developed high power THz sources, the SDI technique allows the use of thick detection crystals.