Temperature Invariant Metasurfaces

TL;DR

This paper introduces a systematic method to create nanophotonic metasurfaces with temperature-invariant optical responses by using hybrid resonators with materials of opposite thermo-optic dispersions, enabling stable device performance across temperature variations.

Contribution

The authors develop a novel approach employing hybrid subwavelength resonators with opposite thermo-optic dispersions to achieve zero effective TO coefficient in metasurfaces.

Findings

Demonstrated temperature-invariant resonant frequency, amplitude, and phase in metasurfaces.

Achieved broad spectral and temperature range stability.

Extended optical manipulation capabilities through control of TO dispersion.

Abstract

Thermal effects are well known to influence the electronic and optical properties of materials through several physical mechanisms and are the basis for various optoelectronic devices. The thermo-optic (TO) effect - the refractive index variation with temperature (dn/dT), is one of the common mechanisms used for tunable optical devices, including integrated optical components, metasurfaces and nano-antennas. However, when a static and fixed operation is required, i.e., temperature invariant performance - this effect becomes a drawback and may lead to undesirable behavior through drifting of the resonance frequency, amplitude, or phase, as the operating temperature varies over time. In this work, we present a systematic approach to mitigate thermally induced optical fluctuations in nanophotonic devices. By using hybrid subwavelength resonators composed from two materials with opposite TO dispersions (dn/dT<0 and dn/dT>0), we are able to compensate for TO shifts and engineer meta-atoms and metasurfaces with zero effective TO coefficient (dn/dT~0). We demonstrate temperature invariant resonant frequency, amplitude, and phase response in meta-atoms and metasurfaces operating across a wide temperature range and broad spectral band. Our results highlight a path towards temperature invariant nanophotonics, which can provide constant and stable optical response across a wide range of temperatures and be applied to a plethora of optoelectronic devices. Controlling the sign and magnitude of TO dispersion extends the capabilities of light manipulation and adds another layer to the toolbox of optical engineering in nanophotonic systems.