1. Nanophotonics Lab, St. Petersburg Academic University, St Petersburg 194021, Russia
2. Institute of Physics, Nanotechnology and Telecommunications, Peter the Great St. Petersburg Polytechnic University, St Petersburg 195251, Russia
3. Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg 194021, Russia
4. Department of Nano-Photonics and Metamaterials, ITMO University, St. Petersburg 197101, Russia
5. Photonics Initiative, Advanced Science Research Center, City University of New York, New York 10031, USA