1. HiLASE Centre, Institute of Physics of the Czech Academy of Sciences, Za Radnicí 828, 252 41 Dolní Břežany, Czech Republic
2. Department of Analytical Chemistry, University of Chemistry and Technology, Prague Technická 5, 166 28 Prague, Czech Republic
3. Department of Optical Materials, Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic