1. ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
2. Novel Photonic Glasses Research Group, Electrical Systems & Optics Research Division, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom
3. Physics Department, University of Warwick, Coventry CV4 7AL, United Kingdom