Phase-change Reconfigurable Metasurfaces @ IEEE COMCAS 2021

Optical metasurfaces, i.e., ultra-thin arrays of sub-wavelength antennae, have enabled a new range of photonic devices with unprecedented functionalities in sculpting wavefronts and substantially reduced form-factor. Special interest has been drawn to a class of so-called ‘active metasurfaces’, whose optical properties can be modulated post-fabrication, particularly by non-mechanical effects. In this talk, I will present our team’s approach to implementing reconfigurable meta-optics by leveraging low-loss phase-change materials, exemplified by Ge2Sb2Se4Te, and novel design switching methodology. Based on both material and design advances, we demonstrated a mid-infrared varifocal metalens that features aberration-free imaging, unprecedentedly low cross-talk with a contrast ratio of nearly 30 dB, and considerably enhanced focusing efficiency exceeding 20% in both states. These research findings open up new avenues for further development of ultra-compact reconfigurable optical devices for imaging, sensing, display, and optical ranging applications.