Reconfigurable, Temperature Resilient Phase‐Change Metasurfaces Fabricated via High Throughput Nanoimprinting Lithography

The combination of metasurfaces with chalcogenide phase-change materials is a highly promising route toward the development of multifunctional and reconfigurable nanophotonic devices. However, their transition into real-world devices is hindered by several technological challenges. This includes, amongst others, the lack of large area photonic architectures produced via scalable nanofabrication methods as required for free-space photonic applications, along with the ability to withstand the high temperatures needed for the phase-change process. In this work, we present a scalable nanofabrication strategy for the production of reconfigurable metasurfaces based on high-throughput, large-area nanoimprint lithography that is fully compatible with chalcogenide phase-change materials processing. Our approach involves the direct imprinting of high-melting-point, thermally stable TiO₂ nanoparticle pastes, followed by the deposition of an Sb₂Se₃ thin film as the phase-change material active layer. The patterned TiO₂ film enables the creation of thermally robust metasurfaces, overcoming the limitations of conventional polymer-based nanoimprinting techniques. The versatility of our approach is showcased by producing phase-change devices with two distinct functionalities: (i) metasurfaces with tunable spectral band switching and amplitude modulation capabilities across the near- to mid-infrared, and (ii) reconfigurable chiral metasurfaces, whose chiroptical activity can be switched between the visible and the near-infrared. Experimental results show excellent agreement with numerical simulations and reveal high uniformity across large areas. This work provides a universal, thermally robust and scalable platform for the production of reconfigurable metasurfaces based on phase-change materials, paving the way to low-cost, photonic devices with reconfigurable optical responses that could be extended far beyond the applications demonstrated here.