Terahertz-wave absorption in liquids measured using the evanescent field of a waveguide

摘要

A technique is presented for the measurement of the absorption properties of liquids in the terahertz wave range, based on the interaction between the liquid and the evanescent wave covering the surface of a cylindrical waveguide. The presence of a medium around the waveguide rod has a measurable effect on the overall end-to-end transmission of the waveguide. As demonstration, we report the absorption spectra of water by using several types of waveguide.