Transmittance analysis of electromagnetic waves transmitting through regions of five different refractive indices

Abstract

When measuring the physical properties of a liquid using terahertz time-domain spectroscopy, a liquid cell with a window is generally used. If the window material is thin, the influence of multiple reflections inside the window plate cannot be ignored. Considering multiple reflections inside the window, an analytical function that includes two windows must be used. Normally, the transmittance of a multilayer structure is determined by simulation using the transfer matrix method or a method that calculates multiple reflection due to reflection interference, however there are few reports that summarize the calculation process and derive the transmission function for analyzing physical properties. Therefore, in this study, in order to obtain the transmission function of electromagnetic waves that pass-through regions with five different refractive indices, we define boundary conditions and substitute to Maxwell's equations to obtain exact analytical solutions.