1. Department of Electrical Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
2. Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
3. Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
4. Key Laboratory of Computer Vision and System of Ministry of Education, Tianjin University of Technology, Tianjin 300384, China