1. Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210, USA
2. NAS-NRC Postdoctoral Research Fellow Residing at the U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
3. U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
4. Departments of Physics and Electrical Engineering, Wright State University, Dayton, Ohio 45435, USA
5. Department of Physics, Arizona State University, Tempe, Arizona 85287, USA