Open AccessDecoupling substrate thickness and refractive index measurement in THz time-domain spectroscopy
Author(s) -
Farah Vandrevala,
Erik Einarsson
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.001697
Subject(s) - refractive index , optics , terahertz radiation , materials science , decoupling (probability) , substrate (aquarium) , terahertz spectroscopy and technology , spectroscopy , time domain , reflection (computer programming) , optoelectronics , physics , computer science , oceanography , quantum mechanics , control engineering , engineering , computer vision , programming language , geology
Terahertz time-domain spectroscopy (THz-TDS) relies heavily on knowing precisely the thickness or refractive index of a material. In practice, one of these values is assumed to be known, or their product is numerically optimized to converge on suitable values. Both approaches are prone to errors and may mask some real features or properties of the material being studied. To eliminate these errors, we use THz-TDS in reflection geometry to accurately and independently determine both thickness and refractive index by illuminating the step-edge of a substrate atop a metal stage. This method relies solely on the relative time delay among three reflected pulses, and therefore forgoes the need for optimization or assumption of substrate parameters.