Terahertz Frequency-Domain Spectroscopy Method for Vector Characterization of Liquid Using an Artificial Dielectric

A device for performing vector transmission spectroscopy on aqueous and polar solvent specimens at terahertz frequencies is presented. The device works on the principle of artificial dielectric birefringence by making a microfluidic grating in silicon. The device enables the direct measurement of the complex dielectric function of a liquid, across a wide terahertz band using a Fourier transform infrared spectrometer. Characterization data from a range of liquid specimens, including alcohol, acetone, hydrogen peroxide and whiskies are presented. Using microfluidic sampling, specimen handling is straightforward and direct measurements on strongly terahertz absorbing solvents are possible. The method is scalable to longer or shorter wavelengths.