1. Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
2. Institute
of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, Albert-Einstein-Str. 15, 07745 Jena, Germany
3. Center
for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States