Polarization-maintaining reflection-mode THz time-domain spectroscopy of a polyimide based ultra-thin narrow-band metamaterial absorber

Abstract

This paper reports the design, the microfabrication and the experimental characterization of an ultra-thin narrow-band metamaterial absorber at terahertz frequencies. The metamaterial device is composed of a highly flexible polyimide spacer included between a top electric ring resonator with a four-fold rotational symmetry and a bottom ground plane that avoids misalignment problems. Its performance has been experimentally demonstrated by a custom polarization-maintaining reflection-mode terahertz time-domain spectroscopy system properly designed in order to reach a collimated configuration of the terahertz beam. The dependence of the spectral characteristics of this metamaterial absorber has been evaluated on the azimuthal angle under oblique incidence. The obtained absorbance levels are comprised between 67% and 74% at 1.092 THz and the polarization insensitivity has been verified in transverse electric polarization. This offers potential prospects in terahertz imaging, in terahertz stealth technology, in substance identification, and in non-planar applications. The proposed compact experimental set-up can be applied to investigate arbitrary polarization-sensitive terahertz devices under oblique incidence, allowing for a wide reproducibility of the measurements.

Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy

“…For all acquisitions, the scan range was set to 100 ps and the data were collected with a time resolution of Δt=33.3 fs. 16,17 Fig. 1 Experimental setup.…”

Fractal interwoven resonator based penta-band metamaterial absorbers for THz sensing and imaging

“…Particularly, absorbent metamaterials compatible with micro-electro-mechanical systems (MEMS), or microsystems-based fabrication have been at the center of special interest for THz band sensing/imaging technologies [11][12][13] . The metamaterial unit cell dimensions required for THz interaction are of the order of tens of micrometers, and micro-fabrication processes based on photolithography can provide high precision 14 .…”

Terahertz Radiation Transport in Photonic Glasses

“…This is made possible by new coherent THz sources, which are opening the road to novel investigations. [19][20][21] Following previous experimental [22,23] and theoretical [24] studies on the disorder-driven THz propagation, here we report on an experimental study by THz time-domain spectroscopy (THz-TDS). The advantage in using such a spectroscopic technique resides in the possibility to access the amplitude and phase of the EM field, and to assess different propagation regimes in properly fabricated random samples.…”