Subwavelength dielectric resonators have enabled new classes of low-loss dielectric nanophotonic devices. However, active tuning of these resonators is still limited, for the most part, to sub-linewidth tuning.
In this work, we demonstrate ultrawide dynamic tuning of PbTe resonators, fabricated via both laser ablation and a novel solution-processing approach. Taking advantage of the extremely large thermo-optic (TO) coefficient and a high refractive index of PbTe, we demonstrate high-quality factor Mie resonances that tuned by several linewidths with temperature modulations as small as ΔT ∼ 10 K. We reveal that the origin for this exceptional tunability is due to an increased TO coefficient of PbTe at low temperatures. When combined into metasurface arrays (simulated by yours truly), these effects can be exploited in ultra-narrow active notch filers and metasurface phase shifters.
These findings demonstrate the enabling potential of PbTe as a versatile, solution-processable, and highly tunable nanophotonic material.