1. Skolkovo Institute of Science and Technology, Moscow 121205, Russia
2. Moscow Institute of Physics and Technology, Moscow region, Dolgoprudny 141700, Russia
3. Novosibirsk State University, Novosibirsk 630090, Russia
4. Novosibirsk State Technical University, Novosibirsk 630073, Russia
5. Fiber Optic Research Center, Moscow 119333, Russia
6. Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
7. Department of Applied Physics and Department of Chemistry and Materials Science, Aalto University, FI-00076 Aalto, Espoo, Finland