Ultrathin Yttria‐Stabilized Zirconia as a Flexible and Stable Substrate for Infrared Nano‐Optics

Infrared (IR) technologies have become increasingly relevant as they offer a wide range of applications, from thermal imaging to chemical and biological vibrational spectroscopy. Substrate materials, such as calcium fluoride and zinc selenide, are commonly used for IR optics. Unfortunately, they are typically fragile or hygroscopic, thus potentially producing problems during device fabrication and in the long-term functional operation. Here, yttria-stabilized zirconia (YSZ) ceramic is introduced as a flexible and stable platform for IR nano-optics. In particular, the YSZ substrate is combined with metallic nanostructures and graphene to demonstrate new plasmonic, polarizing, and transparent heating devices, which, at the same time, enable high-temperature processing and withstand harsh environments thanks to the high YSZ thermal and chemical stability. In addition, it is shown that the YSZ substrate is mechanically flexible, ideally suited for making foldable or bendable devices, and for low-cost large-scale roll-to-roll fabrication processes. The combination of all the aforesaid features, which are not available from other alternative materials, and this work offers compelling evidence that ultrathin YSZ is a unique substrate for IR applications.