Metamaterials research having potential applications in high-speed data transmission, medical imaging and other kinds of imaging and remote sensing is the focus of a U.S. Department of Defense project funded for five years at $7.5 million.
Penn State is part of this six-member Multi-University Research Initiative by the Air Force Office of Scientific Research. The project is led by Mark Cappelli, professor of mechanical engineering, Stanford University. Also collaborating with Stanford are the University of Texas at Austin, Tufts University, UCLA and the University of Washington.
Penn State researchers will focus on the fundamental science necessary to develop plasma photonic crystals and plasma-embedded metamaterials that operate in the terahertz range. Terahertz is the region of the electromagnetic spectrum that lies between far infrared and microwave, and is a nonionizing frequency invisible to the human eye. This regime is already being used in airport surveillance and astronomy.
The researchers will generate the plasmas inside holes in the metamaterial arrays using radio frequency excitation with the entire device encapsulated in an inert gas. Using micro-lens arrays, focused lasers will generate very dense, highly ionized plasma arrays. Unlike the metal structures of typical metamaterials, researchers can control a plasma's dielectric properties by varying the plasma density. Plasmas afford the possibility of controlling metamaterials at high bandwidth. This will enable such applications as antennas with beam steering, filter devices, multiplexers, phase shifters and electro-optical modulators.
Researchers at Penn State will be the primary team charged to develop a new class of low-loss dielectric resonators and multilayer low temperature co-fired ceramics to replace the usual metallic split-ring resonators found in traditional metamaterial structures. Metamaterials are artificial structures with sub-wavelength features that can interact with electromagnetic waves in a manner unlike that of natural materials. Long-term goals of metamaterials research include invisibility cloaking devices and perfect lenses to capture short-range light waves for fine detail light microscopy.
The principal investigators at Penn State are Clive Randall, professor of materials science and engineering, and Michael Lanagan, professor of engineering science and mechanics. The Penn State team members are pioneers in the development of dielectric materials and leaders in the long-running Center for Dielectric Studies, an industry supported research center that recently was renewed with technical new opportunities with North Carolina State University as the NSF I/UCRC Center for Dielectrics and Piezoelectrics.