Affiliation: | aNational Institute for Laser, Plasma and Radiation Physics, Bucharest-Magurele, RO-76900, Romania;bInstitute of Electro-optical Science and Technology, National Taiwan Normal University, 88, Sec.4, Ting-Chou RD., Taipei, Taiwan 116, ROC;c“Valahia” State University of Targoviste, Department of Physics, Targoviste, Romania |