Thermal tunability in terahertz metamaterials fabricated on strontium titanate single crystal substrates

TL;DR

This paper demonstrates how cooling a terahertz metamaterial on strontium titanate significantly shifts its resonance frequency due to temperature-dependent dielectric properties, enabling tunable terahertz devices.

Contribution

It presents the first experimental demonstration of thermal resonance tuning in terahertz metamaterials using a strontium titanate substrate.

Findings

Resonance frequency shifts by about 50% when cooled from 409 K to 150 K.

Resonance strength remains largely unchanged during tuning.

The tuning mechanism is attributed to the temperature-dependent dielectric constant of SrTiO3.

Abstract

We report an experimental demonstration of thermal tuning of resonance frequency in a planar terahertz metamaterial consisting of a gold split-ring resonator array fabricated on a bulk single crystal strontium titanate (SrTiO3) substrate. Cooling the metamaterial starting from 409 K down to 150 K causes about 50% shift in resonance frequency as compare to its room temperature resonance, and there is very little variation in resonance strength. The resonance shift is due to the temperature-dependent refractive index (or the dielectric constant) of the strontium titanate. The experiment opens up avenues for designing tunable terahertz devices by exploiting the temperature sensitive characteristic of high dielectric constant substrates and complex metal oxide materials.