1. 1School of Electrical & Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA
2. 2Nano-Meta Technologies Inc., 1281 Win Hentschel Boulevard, West Lafayette, IN 47906, USA
3. 3Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA
4. 4DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Lyngby, DK-2800, Denmark