Design and Optimization of Phase-Change Metasurfaces for Infrared Energy and Biosensing Applications

Abstract

The area of nanophotonics has been the focus of researchers recently due to its high potential to overcome the limitations of scaling in electronic devices. One of the most popular devices in this field is the metasurface. A metasurface consists of a periodic or aperiodic array of spaced units called ’meta-atoms’, where the interaction between these neighboring elements provide unprecedented properties that cannot be obtained using a a regular array of antennas. By tuning the shape and structure of the meta-atoms, electromagnetic wave interaction with the metasurface can be manipulated to achieve a plethora of response characteristics. For active applications that require tunability of the response, a passive metasurface cannot be used to adapt to the varying operating conditions. Tunability of metasurfaces can then be achieved by using phase-changing materials. This type of materials can attain different optical properties by applying external stimulus such as heat, electric current, or laser pulses. The change in the optical properties would be beneficial for applications requiring reconfigurability or adaptation. In this thesis, I demonstrate the employment of volatile (Vanadium Dioxide) and non-volatile (Germanium Antimony Telluride) examples of phase-change materials to design reconfigurable metasurfaces operating at different bands in the infrared regime. I show metallic and dielectric-based structures that employ volatile and non-volatile phase-change materials, as well as apply physics such as plasmonics and bound states in the continuum to design and optimize metasurface structures for energy and biosensing applications.