1. Nonlinear
Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra ACT 2601, Australia
2. Institute
of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-University Jena, 07743 Jena, Germany
3. Center
for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
4. Sandia National Laboratories, Albuquerque, New Mexico 87185, United States