Open AccessHigh-precision THz-TDS via self-referenced transmission echo method
Author(s) -
Jon Gorecki,
Nick Klokkou,
Lewis Piper,
S. Mailis,
Nikitas Papasimakis,
Vasilis Apostolopoulos
Publication year - 2020
Publication title -
applied optics
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 197
eISSN - 2155-3165
pISSN - 1559-128X
DOI - 10.1364/ao.391103
Subject(s) - optics , refractive index , terahertz radiation , transmission (telecommunications) , echo (communications protocol) , materials science , time domain , laser , pulse (music) , absorption (acoustics) , attenuation coefficient , physics , computer science , telecommunications , computer network , detector , computer vision
Terahertz time-domain spectroscopy (TDS) is a powerful characterization technique which allows for the frequency-dependent complex refractive index of a sample to be determined. This is achieved by comparing the time-domain of a pulse transmitted through air to a pulse transmitted through a material sample; however, the requirement for an independent reference scan can introduce errors due to laser fluctuations, mechanical drift, and atmospheric absorption. In this paper, we present a method for determining complex refractive index without an air reference, in which the first pulse transmitted through the sample is compared against the "echo", where the internal reflections delay the transmission of the echo pulse. We present a benchmarking experiment in which the echo reference method is compared to the traditional air method, and show that the echo method is able to reduce variation in real refractive index.