Optical Properties of Materials in the Terahertz Spectral Range

<p class="MsoNormal" style="text-align:justify">The study presents a database of optical properties for a wide range of
materials within the terahertz (THz) radiation range. The analysis focused on
the absorption coefficient and refractive index in the frequency domain in the
range from 100 GHz to 1 THz. A total of 99 materials were analyzed using THz time-domain
spectroscopy (THz-TDS), including 56 types of polymers and composites commonly
used in additive manufacturing technologies such as fused deposition modeling (FDM)
and selective laser sintering (SLS), as well as 43 casting materials such as
waxes, clays, soaps, and chocolates. Measurements were performed with the TPS
3000 spectrometer (TeraView) spectrometer in a dry-air chamber on cylindrical
samples with a thickness of 4 mm and a diameter of 13 mm. Additionally,
absorption coefficient measurements for six transparent polymer materials were
conducted over a broad spectral range from 0.1 THz to 200 THz. The data were
obtained by combining THz-TDS measurements with two Fourier Transform Infrared
Spectroscopy (FTIR) measurement ranges: the first spanning 2–20.4 THz and the
second covering 12–200 THz, using the FTIR TermoScientific Nicolet 6700 and
FTIR Bruker VERTEX 80v spectrometers.</p>