Phase-Change Materials for Tunable Infrared Devices

There is a critical need for the development of dynamic IR materials that can be used to form device level components and systems necessary for mid to long wave infrared (3-12 m) applications. To meet these future needs, the team proposes to develop tunable optical elements based around metamaterial surfaces or metasurfaces. Metasurfaces are a class of engineered materials where arrays of sub-wavelength resonant elements are integrated within a surface to impress a desired spectral, directional, or polarization response. Metasurfaces also enable the development of extremely thin spectral tailoring (<500 nm in the MWIR and <1 micron in the LWIR). To address the need for dynamic performance, the team propose to develop a new class of infrared modulators based around phase change materials (PCM). Phase change materials, such as chalcogenide glasses, can be switched between an amorphous and crystalline phase, with each phase possessing significantly different optical properties. Previous work by the team has shown that GeTe based metasurface designs have significant modulation of reflectivity, narrow bandwidth, and can be designed to operate over large portions of the spectra.