Making the Mid-IR nano with epitaxial plasmonic devices

The mid-infrared (mid-IR) spectral range (3-30μm) has become a dynamic field of research for fundamental exploration as well as for more applied research in health and the environment, security and defense, communication, and sensing. At the same time, the field of plasmonics has experienced explosive growth over the past decade, yet the integration of plasmonic structures into mid-IR optical systems has been slower to evolve. While scaling plasmonic geometries to mid-IR wavelengths is actually fairly straightforward, replicating the near-IR/vis optical properties of constituent materials in plasmonic systems is less trivial, leading to very different behavior of scaled systems in these two wavelength ranges. The use of traditional metals for mid-IR plasmonics effectively limits our ability to replicate, at long wavelengths, phenomena associated with ultra-subwavelength optical structures at shorter wavelengths. For this reason, the development of plasmonic metals with mid-IR optical properties resembling traditional plasmonic metals' visible and near-IR properties is an essential step towards the development of nanophotonic structures and devices for mid-IR wavelength light [1].