Laser-Printed Terahertz Plasmonic Phase-Change Metasurfaces

Chalcogenide phase-change materials (PCMs) have offered an appealing material solution by acting as a switchable dielectric layer to tune the electromagnetic properties of terahertz metamaterials and metasurfaces. Here, this work demonstrates large-scale and lithography-free manufacturing of all-PCM terahertz metasurfaces based on direct laser switching of crystalline micro-domains in a thin film with high switching ratio of the emerging plasmonic PCM, In3SbTe2 (IST). The fabricated high-quality IST metasurfaces achieve efficient plasmonic resonances and a large modulation depth with ultrafast response (full width at half maxima of the modulation time approximate to 1.6 ps) in a deep-subwavelength switching volume. For the dynamic evolution of terahertz resonance modes, theoretical modeling reveals a delicate interplay between amorphous and crystalline IST due to the bonding-structure-induced different carrier lifetimes and spatially localized electric fields. These studies open new avenues for realizing all-PCM terahertz ultrafast nanophotonics.