1. S.I. Vavilov State Optical Institute, St. Petersburg, Birzhevaya line, 12, 199034, Russia
2. St. Petersburg State University, Department of Physics, Petrodvoretz, 198904, Russia
3. Design and Technological Institute for Monocrystals SB RAS, Russkaya str. 43, Novosibirsk, 630058, Russia
4. Lawrence Livermore National Laboratory, CA, L-590, P.O. Box 5508, Livermore, California 94550, USA