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The interaction of light and matter is ubiquitous and penetrates every facet of our existence, from the simple joy of watching a sunset to fast-paced developments in energy harvesting and information technology. As such, the control of light-matter interactions is a core topic in materials science with the emergence of the metamaterials paradigm at the dawn of the twenty-first century providing a guiding principle to aid in the realization and advancement of numerous optical and photonic technologies. Central to this paradigm is creating electromagnetic composites consisting of subwavelength “meta-atoms” with properties dictated by judicious design. Simultaneous with the development of metamaterials are advances in the realization and characterization of quantum materials where novel electronic and photonic properties derive from micro-to-mesoscale interactions and phenomena. At the crossroads where metamaterials meet quantum materials enhanced interactions can arise, enabling novel devices and systems.

MEMS-based terahertz metamaterial structures and devices: In collaboration with Prof. Richard Averitt (Physics), our recent research focuses on creating active structures and devices to enhance our ability manipulate and detect far-infrared, or terahertz, radiation by combining electromagnetic metamaterials with MEMS technologies. Recent advances in metamaterials research have highlighted the possibility to create novel devices with unique electromagnetic functionality. Indeed, the power of metamaterials lies in the fact that it is possible to construct materials with a user-designed electromagnetic response at a precisely controlled target frequency. This is especially important for the technologically relevant terahertz frequency regime with a view toward creating new component technologies to manipulate radiation in this hard to access wavelength range. Motivating our effort to advance terahertz science and technology is the unique characteristics of terahertz radiation which includes transparency to materials such as cardboard, plastic, and styrofoam which are opaque at other wavelengths, and sensitivity to molecular signatures of gas phase and solid phase materials including biological agents and chemical explosives. A potential application is spectroscopic imaging and identification of embedded illicit or hazardous materials. While there have been laboratory-based demonstrations, further improvements in terahertz sources, components, and detectors are required for systems which are sufficiently compact and robust for real-world operation.

Bimaterial cantilevers: engineering mechanics for the next generation: Detection/imaging of infrared radiation is of great importance to a variety of applications ranging from night vision to environmental monitoring, biomedical diagnostics, and remote sensing. Recent advances in MEMS have led to the development of uncooled infrared detector arrays which function bases on bending of bimaterial cantilevers upon absorption of infrared energy. Unfortunately, the manufacturability, planarity and reliability for such cantilever microstructures have been always inadequate. Released devices always bend up (or down) due to the imbalanced residual stresses in the multilayered MEMS. Residual stress resulting from thin film fabrication and structure release is the principal source of bent errors in micromachined structures. Stress gradients are particularly troublesome from a detection standpoint, because even relatively small stress variations through the thickness of a thin film can cause significant, undesirable curvatures of the membrane, rendering arrays of structures useless. Our primary focus of this fundamental research is on investigating engineering mechanics. We have developed disruptive micromechanics theories and microfabrication technologies, enabling routine manufacturing of low-cost, lightweight, high-performance, bimaterial cantilever structures and devices for sensing and imaging applications.

Project Examples and Representative Publications

MEMS-based Terahertz Metamaterial Structures and Devices
Bimaterial Cantilevers: Engineering Mechanics for the Next Generation

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