1. Department of Physics, City College of the City University of New York (CUNY), New York, New York 10031, United States
2. Department of Physics, Graduate Center of the City University of New York (CUNY), New York, New York 10016, United States
3. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
4. Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
5. Department of Electrical Engineering and Computer Science and Physics, University of Michigan, Ann Arbor, Michigan 48109, United States