Measurement and Modeling of Terahertz Spectral Signatures from Layered Material

摘要

Many materials such as drugs and explosives have characteristic spectral signatures in the terahertz (THz) band. These unique signatures hold great promise for potential detection utilizing THz radiation. While such spectral features are most easily observed in transmission, real life imaging systems will need to identify materials of interest from reflection measurements, often in non-ideal geometries. In this work we investigate the interference effects introduced by layered materials, which are commonly encountered in realistic sensing geometries. A model for reflection from a layer of material is presented, along with reflection measurements of single layers of sample material. Reflection measurements were made to compare the response of two materials; α-lactose monohydrate which has sharp absorption features, and polyethylene which does not. Finally, the model is inverted numerically to extract material parameters from the measured data as well as simulated reflection responses from the explosive C4.