Extreme metaphotonics with ultra high-index chalcogenide topological insulators

In nanophotonic, small mode volumes, narrow resonance linewidths and field enhancements, fundamentally scales with refractive index values and are key for many implementations involving light-matter interactions. Topological insulators (TI) are a class of insulating materials that host topologically protected surface states, some of which exhibit very high permittivity values. In this talk, I will present my group's latest results on chalcogenide metaphotonics. I start by discussing Chalcogenide Bi2Te3 and Bi2Se3 TIs nanostructures. Using polarized far-field and near field Nanospectroscopy we reveal that Bi2Se3 nanobeams exhibit mid-infrared resonant modes with 2π phase shifts across the resonance. We further demonstrate that Bi2Te3 metasurfaces exhibit deep-subwavelength resonant modes utilizing their record high index value peaking at n~11. Finally we discuss how the anomalous thermo-optic effect in lead chalcogenide can be harnessed for implementing temperature invariant metasurfaces