1. Department of Applied Physics, Aalto University School of Science, FI-00076 Aalto, Finland
2. Institute of Photonics, University of Eastern Finland, FI-80101 Joensuu, Finland
3. Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra 08193, Catalonia, Spain
4. Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University, FI-33101 Tampere, Finland