Cryogenic temperatures as a path towards high-Q terahertz metamaterials

TL;DR

This study investigates how cryogenic temperatures can enhance the quality factor of terahertz metamaterials by reducing losses, with experimental and simulated results showing significant improvements at low temperatures.

Contribution

It demonstrates the potential of cryogenic cooling to significantly improve the Q-factor of terahertz metamaterials, supported by experimental measurements and simulations.

Findings

14% increase in Q-factor at liquid nitrogen temperature

High electron scattering limits Q-factor improvement at room temperature

Simulations predict up to 40% Q-factor increase at 10 K

Abstract

Optical properties of planar thin film metamaterials were measured at room and liquid nitrogen temperatures using terahertz time-domain spectroscopy. The operation of metamaterials at cryogenic temperatures is anticipated to be a promising path towards low-loss metamaterials since nonradiative losses are strongly suppressed due to higher charge mobility. A 14% increase in the quality factor of the resonances was experimentally observed. It was limited by the high electron scattering rate due to defects in thin films. Supplementary simulations assuming metamaterials made of thick films reveal a temperature controlled behaviour and a 40% increase of the Q-factor at 10 K.