https://doi.org/10.1140/epjs/s11734-021-00215-9
Review
A review on numerical methods for thickness determination in terahertz time-domain spectroscopy
1
Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, 741246, Kolkata, West Bengal, India
2
Laboratory for Electro-Optics Systems, ISRO, Bangalore, India
Received:
22
March
2021
Accepted:
5
July
2021
Published online:
20
July
2021
The use of numerical methods for thickness extraction in terahertz time-domain spectroscopy (THz-TDS) is highly deterministic in improving the accuracy of optical parameters significantly. Here, several commonly used thickness determination methods employing THz-TDS, both in transmission and reflection geometry, are discussed and reviewed. The effectiveness of these methods is compared experimentally in this tutorial type review by measuring transmitted THz field through both optically thick (
427 
thick sapphire wafer) and thin ( 65 thick polymer film) samples, and then extracting their thickness values by using these numerical methods separately. Furthermore, we propose a modification to one of the numerical methods (i.e., quasi-space method) to further improve the accuracy of thickness measurement in transmission geometry.
© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2021
