1Center for Optoelectronics and Optical Communications, The University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223, USA
2Department of Chemistry, The University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223, USA
3Department of Electrical and Computer Science, The University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223, USA