Two methods for modelling the propagation of terahertz radiation in a layered structure

Modelling the interaction of terahertz (THz) radiation with biological tissue poses many interesting problems. THz radiation is neither obviously described by an electric field distribution or an ensemble of photons and biological tissue is an inhomogeneous medium with an electronic permittivity that is both spatially and frequency dependent making it a complex system to model.</p> <p>A three-layer system of parallel-sided slabs has been used as the system through which the passage of THz radiation has been simulated. Two modelling approaches have been developed a thin film matrix model and a Monte Carlo model. The source data for each of these methods, taken at the same time as the data recorded to experimentally verify them, was a THz spectrum that had passed though air only.</p> <p>Experimental verification of these two models was carried out using a three-layered in vitro phantom. Simulated transmission spectrum data was compared to experimental transmission spectrum data first to determine and then to compare the accuracy of the two methods. Good agreement was found, with typical results having a correlation coefficient of 0.90 for the thin film matrix model and 0.78 for theMonte Carlo model over the full THz spectrum. Further work is underway to improve the models above 1 THz.