Utilizing multilayer structures to enhance terahertz characterization of thin films ranging from aqueous solutions to histology slides

Sun, Qiushuo, Kai Liu, Xuequan Chen, Xudong Liu, A. I. Hernandez-Serrano, and Emma Pickwell-MacPherson. "Utilizing multilayer structures to enhance terahertz characterization of thin films ranging from aqueous solutions to histology slides." Optics letters 44, no. 9 (2019): 2149-2152.

Abstract

We propose a multilayer geometry to characterize thin-film samples in reflection terahertz time domain spectroscopy. Theory indicates that this geometry has higher sensitivity compared to ordinary transmission or reflection geometries when characterizing both low- and high-absorption samples. Pure water and water–ethanol mixtures are measured to verify the characterization accuracy of the proposed geometry and its capability to measure trace liquids. Paraffin-embedded oral cancer tissue is imaged to further show how the proposed geometry enhances the sensitivity for solid low-absorptive films.

for full paper see https://www.osapublishing.org/ol/abstract.cfm?uri=ol-44-9-2149

"The TF liquid measurements were conducted using the Terapulse 4000 from Teraview Ltd. The ethanol (≥99.8%) was from SIGMA-ALDRICH CO. The dove prism was made of fused quartz with a top angle of 38°. The top medium in the liquid measurements was a 2mm-thick fused quartz substrate. 25 µm Teflon spacers were sandwiched in the middle between the quartz prism and the substrate. The incident wave was p-polarized"