Permittivity and Loss Characterization of Polymer Films for Terahertz Applications

Abstract

With the development of science, terahertz (THz) technology has matured gradually. More attention has been given to THz technology in recent years due to its superiority for non-destructive testing. Dielectric polymers are widely used in electrical engineering because of their unique electrical properties. Spectral detection plays a vital role in studying the internal motion and micro-scale forces. THz time-domain spectroscopy (THz-TDS) is a powerful complement to other spectroscopy techniques because of its unique frequency band that energetically vibrates and rotates the polymer structure. Herein, we apply THz-TDS with an effective frequency of 0.1–1 THz at 55% relative humidity. TDS at 0.1–1 THz to conduct fundamental research on several commonly utilized dielectric non-polar and polar polymer films including PC, FTPE, PMMA, HDPE, PA6, PET, PP. In this study, the THz complex refractive index and dielectric constants of various polymer films are determined and compared with previously reported values. In addition, the loss mechanism of THz radiation in polymers is characterized by correlating the absorption coefficients of the materials with the loss tangents. Herein, we demonstrate that the sample preparation significantly impacts the loss behavior of polymer materials and quantify the effect of crosslinking on the dielectric constant across the entire frequency band. The findings presented herein are expected to contribute to the design and development of optical and electronic devices in the future.