1. NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, United States
2. College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816, United States
3. Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, P. R. China
4. Department of Materials Science & Engineering, University of Central Florida, Orlando, Florida 32816, United States