1. Institute of Physics; ASCR; v.v.i, Cukrovarnická 10 16200 Prague Czech Republic
2. National Institute of Advanced Industrial Science and Technology (AIST); Central 5, 1-1-1 Higashi Tsukuba 3, 05-8565 Japan
3. Faculty of Electrical Engineering; Czech Technical University; Technická 2 166 27 Prague Czech Republic