1. Photonics Laboratory, Tampere University, Korkeakoulunkatu 3, Tampere 33720, Finland
2. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, Wroclaw 50-422, Poland
3. Univ Rennes, CNRS, ISCR [(Institut des Sciences Chimiques de Rennes)], UMR 6226, Rennes F-35000, France