1. School of Engineering and Information Technology, University of New South Wales, Canberra, ACT 2600, Australia
2. Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics, ETH Zurich, 8093 Zurich, Switzerland
3. Nonlinear Physics Centre, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
4. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
5. Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia