Simultaneous determination of thickness and refractive index based on time-of-flight measurements of terahertz pulse

Abstract

We present a simple technique for simultaneous determination of thickness and refractive index of plane-parallel samples in the terahertz radiation domain. The technique uses time-of-flight measurements of the terahertz pulse. It has been employed on nine different polymers and semiconductor materials, which are transparent for terahertz frequencies. Our results of thickness measurement are in good agreement with micrometer reading. The accuracy in the determination of refractive index is on the order of two decimal points.

Measurement of thickness and refractive index using femtosecond and terahertz pulses

“…Using femtosecond pulses, we have measured thickness and group refractive index at a wavelength of 780 nm for three different materials. Accuracy in thickness measurement is around 2-3 µm and refractive index is measured with a precision up to three decimal points which is equal to or better than some previous demonstrations [4,6,7,17]. Accuracy can be improved by many folds using a highly precise translation stage in the autocorrelator.…”

“…Previously, we have reported a simple technique to measure the thickness and refractive index of different semiconductors and polymers in the THz region [17]. In this paper we demonstrate simultaneous determination of thickness and group refractive index of parallel-plane samples using time-of-flight measurements of femtosecond and THz pulses.…”

Preparation of freestanding graphene-based laminar membrane for clean-water intake via forward osmosis process

“…3c and d). In principle, the time delay is the function of the refractive index and thickness of sample material, and can be dened mathematically as follows: 43 Dt z ðn 2 À n 1 Þd c ;…”

Terahertz and Photoelectron Emission from Nanoporous Gold Films on Semiconductors

“…The weaker THz pulse around −8.41 ps was reflected from GaAs-NPG interface. According to the time delay between two peaks, we could calculate the average refractive index of the substrate according to [26]:nsub=c·τ/d where n sub is the refractive index of the substrate in THz region, and c speed of light in vacuum, and τ the time delay between two THz peaks reflected from air-GaAs and GaAs-NPG interface, and d the optical path difference. The corresponding time delays τ are 8.41, 8.41, 8.40, 8.39 and 8.37 ps under the pump intensity 0, 5.9, 23.6, 41.3, and 58.9 GW/cm 2 , respectively.…”