Modified Transfer Matrix Method for the Extraction of Material Properties via Terahertz Time-Domain Spectroscopy

TL;DR

This paper presents a modified transfer matrix method combined with a genetic algorithm to accurately determine material refractive indices from terahertz spectroscopy data, applicable across various materials and frequency ranges.

Contribution

It introduces a novel approach that improves the accuracy and applicability of extracting optical constants from terahertz time-domain spectroscopy data.

Findings

Accurately determines refractive indices across 0.1-15 THz.

Applicable to a wide range of materials and structures.

Outperforms existing methods in accuracy.

Abstract

Terahertz Time-Domain Spectroscopy is a powerful technique for extracting the low-frequency optical properties of materials. However, the optical constants are difficult to determine directly from the experimental transfer function, such that various numerical approximations must be implemented to describe specific conditions. Here, we introduce a modified Transfer Matrix Method that uses a genetic algorithm for optimization to determine the refractive index of materials in the THz regime. We show that this approach is generally applicable across a wide range of refractive indices, structures, and frequency ranges. Our method is intuitive and yields accurate results compared to leading methods across a wide spectral range (0.1 - 15 THz).