1. Department of Physics, University College Cork, Cork, Ireland
2. Tyndall National Institute, University College Cork, Lee Maltings, Dyke Parade, Cork, Ireland
3. Georgia Tech-CNRS UMI 2958, Georgia Tech Lorraine, 2 Rue Marconi, 57070 Metz, France
4. School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0250, USA
5. Centre for Advanced Photonics and Process Analysis, Cork Institute of Technology, Cork, Ireland
6. Université Côte d'Azur, CNRS, Institut de Physique de Nice, Valbonne F-06560, France
7. National Research University of Information Technologies, Mechanics and Optics, 49 Kronverksky Pr., St Petersburg 197101, Russia
8. Optique Nonlinéaire Théorique, Université libre de Bruxelles, Campus de la Plaine, CP 231, 1050 Bruxelles, Belgium