OP: MEMS-driven photonic metamaterials: dynamic wavefront tailoring with reconfigurable metasurfaces

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Part A:This project aims to develop tunable metamaterials driven by integrated microelectromechanical system (MEMS) actuators for dynamic control of terahertz and infrared light. Photonic metamaterials have proven to be a powerful tool to manipulate light propagation. However, there is an existing challenge concerning the development of random access metamaterials with on-demand effective properties. In order to overcome this grand challenge, MEMS actuators will be integrated with metamaterial unit cells, enabling on-demand light manipulation. The physics of phase control, design of unit cells, micro-/nanofabrication, and system integration schemes will be investigated to realize metamaterial devices that can manipulate the wavefront of terahertz and infrared light as desired, enabling, for example, dynamic beam steering and tunable focusing. The metamaterial devices that will be developed are multifunctional, compact, and dynamically tunable, offering significant potential in comparison to conventional optical devices. The success of this project will boost the development of opto-electronic systems in areas such as spectroscopy, high-resolution imaging, and light detection and ranging (LiDAR), which are widely used in healthcare and national security and defense. This project provides a platform to educate young researchers, including women and underrepresented minorities, fostering their passion in fundamental optics and photonics research and applied engineering technologies.Part B:Metamaterials have revolutionized electromagnetism during the past decade resulting in myriad new phenomena including cloaking, negative refractive index, and tunable electromagnetic composites. The goal of this project is to develop dynamically reconfigurable metamaterials to manipulate the wavefront of terahertz and infrared light, which is enabled by integrating MEMS actuators in metamaterial unit cells. For efficient wavefront manipulation, the key is to achieve full-span phase coverage with constant amplitude in the response of metamaterial unit cells. However, the amplitude and phase response of the majority of metamaterial designs are bounded, making it challenging to achieve high-efficiency wavefront manipulation. In the proposed work, the coupling effect between the metamaterial layer and a ground plane or two layers of metamaterials will be studied to design structures that can modulate the phase response with little effect on the amplitude response, i.e. decoupling amplitude and phase modulation. Fabrication processes will be developed to construct metamaterial devices based on both surface and bulk micro-/nanomachining techniques. The integration of metamaterial unit cells and MEMS actuators will be investigated and optimized to make each unit cell accessible individually by employing advanced MEMS integration and packaging techniques including three-dimensional wire routing, through silicon vias (TSVs) and flip chip bonding. Finally, tunable metamaterial devices exhibiting multifunctionality will be demonstrated to manipulate terahertz and infrared light. This includes dynamic beam steering and focusing, which cannot be achieved with state-of-the-art techniques, for a variety of applications, such as spectroscopy, imaging, and LiDAR.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.