1. Department of Physics and Engineering, Delaware State University, Dover, DE 19901-2277, USA
2. Optical Science Center and Applied Research, Delaware State University, Dover, DE 19901-2277, USA
3. Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA
4. Science Program, Texas A&M University at Qatar, P. O. Box 23874, Doha, Qatar