Material Parameter Extraction Using Terahertz Time-Domain Reflection Spectroscopy in the Presence of Air Gaps

To solve the phase ambiguity problem in the THz reflection spectroscopy, current material parameter extraction methods require the sample to make an ideal contact with an optically transparent window. We treat these samples as a multilayer system and present a new algorithm that estimates the thickness of the potential air gap and calculates the complex refractive index of the samples.