1. Center for Magneto-Optical Research, Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków, Poland
2. Department of Optical Fibres Technology, Faculty of Chemistry, Marie Curie-Skłodowska University, pl. M. Curie-Skłodowskiej 3, PL-20-031 Lublin, Poland