1. Institute of Applied Physics, Moldova State University, 5 Academiei str., Chisinau, MD 2028, Republic of Moldova
2. Catalonia Institute for Energy Research (IREC), C/Jardins de les Dones de Negre 1, Sant Adrià de Besòs, Barcelona 08930, Spain
3. Universität Leipzig, Felix Bloch Institute for Solid State Physics, Linnéstraße 5, Leipzig D-04103, Germany
4. Instituto de Óptica, IO-CSIC, C/Serrano 121, Madrid 28006, Spain
5. Belarusian State University of Informatics and Radioelectronics, P. Brovka 6, Minsk 220013, Belarus
6. Universidad Autónoma de Madrid, Department of Applied Physics, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain
7. CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, Warsaw PL-01-142, Poland