Integrating microsystems with metamaterials towards THz and infrared metadevices

Metamaterials are a major class of artificially engineered electromagnetic (EM) composites that enable myriad novel routes to control light. During the past two decades, metamaterials have emerged as a focal point for manipulating EM waves spanning from radio frequencies through the visible, given their capacity to the creation of novel effective optical properties. This includes, as but a few examples, negative refractive index, giant circular dichroism, local field enhancement, and wave-front tuning. At the same time, microelectromechanical systems (MEMS) or microsystems is a powerful platform to enhance the functionality of metamaterials to realize “metadevices”. Metadevices exhibit dynamic properties, including modulation of the intensity and phase of light, manipulation of near-field interactions, and wave-vector control. Compared to tunable devices constructed using solely naturally available materials, metadevices exhibit higher tunability, have more degrees of freedom, and can be made more compact. In this dissertation, the fundamental physics and engineering applications of metadevices have been thoroughly studied at terahertz (THz) and IR frequencies. First, a polarization insensitive air spaced triple band metamaterial perfect absorber (MMPA) has been investigated using a suitably modified interference theory. Second, using coupled mode theory (CMT) and electromagnetic simulations, Fano resonances, bound states in continuum (BIC), and toroidal dipole excitations have been modeled and experimentally investigated for both stationary and reconfigurable THz-MEMS based devices. Third, using a MMPA structure, a metamaterial-enhanced micro-bolometer for detecting long wave infrared radiation has been realized. Finally, using CMT, a tunable gradient metasurface has been demonstrated. This device integrates MEMS actuators for full-span phase modulation, resulting in multifunctional metamaterial devices for spatial light modulation, dynamic beam steering and focusing, and active vector-beam generation at terahertz frequencies. Broadly, this dissertation presents a detailed study of THz and IR metadevices, advancing the scientific underpinnings and application potential for use in future sensing and communication modalities.2023-05-23T00:00:00