1. Department of Aerospace Engineering, Texas A&M University, College Station, Texas 77843, United States
2. Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
3. Physics Program, Graduate Center, City University of New York, New York, New York 10016, United States
4. Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States