Thermo-optically Reconfigurable PbTe Mie Resonator Meta-atoms

TL;DR

This paper demonstrates the use of PbTe Mie resonators with high quality factors that can be thermally tuned over several linewidths with minimal temperature change, enabling dynamic reconfigurable optical metasurfaces.

Contribution

The authors introduce a novel thermo-optic tuning method for PbTe Mie resonators, achieving ultra-wide tuning ranges with small temperature variations, fabricated via laser ablation and solution-processing.

Findings

High-quality Mie resonances in PbTe can be thermally tuned by several linewidths.

Tuning is achieved with temperature changes as small as 10K.

PbTe metasurfaces enable ultra-narrow active optical filtering and phase shifting.

Abstract

Subwavelength Mie resonators have enabled new classes of optical antennas1-4, photodetectors5,6, antireflection coatings7, and magnetic mirrors8 and can act as the basic meta-atoms constituents of low-loss dielectric metasurfaces2-4,8-10. In any application, tunable Mie resonances are key to achieving dynamic and reconfigurable operation11,12. Sub-linewidth tuning has been achieved via coupling to liquid crystals13, ultrafast free-carrier injection14,15,16,17, stretchable substrates18 and with phase change materials19. Here, we demonstrate ultra-wide dynamic tuning of PbTe Mie resonators fabricated via both laser ablation and a novel solution-processing approach. Taking advantage of the extremely large thermo-optic (TO) coefficient and high refractive index of PbTe, we demonstrate high-quality factor Mie-resonances that are tuned by several linewidths with temperature modulation as small as {\Delta}T~10K. When combined into metasurface arrays these effects can be exploited in ultra-narrow active notch filers and metasurface phase shifters that require only few-kelvin modulation. These findings demonstrate the enabling potential of thermo-optically tunable PbTe meta-atoms and metasurfaces.