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

ABSTRACT 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 TiO ₂ nanoparticle pastes, followed by the deposition of an Sb ₂ Se ₃ thin film as the phase‐change material active layer. The patterned TiO ₂ 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.