Cryogenic temperatures as a path toward high-Q terahertz metamaterials

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 toward 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 behavior and a 40% increase in the quality factor at 10 K.