Abstract
The current state-of-the-art in materials used for IR optical components (e.g. focusing elements, waveplates or prisms) is far from ideal. This problem is exacerbated by the long free-space wavelengths associated with the mid-wave IR (MWIR) to terahertz (THz) spectral domains. Through the use of polaritons, one can surpass the diffraction limit and thus the limitations of these long free-space wavelengths can be circumvented. The two most prevalent varieties are the surface plasmon (SPP) and surface phonon polariton (SPhP), resulting from the coupling of light with electronic charges in a metal or ionic charges on a polar lattice, respectively. Each exhibits significant limitations, for instance the narrow, material specific operational "Reststrahlen band" of SPhPs and the relatively high optical losses in SPPs. Thus, it would be ideal to identify a method to dictate the IR/THz response, while retaining the positive attributes of both.