[1] Univ Szeged, Hungarian Acad Sci, Res Grp Laser Phys, H-6701 Szeged, Hungary
[2] Univ Nacl Ingn, Fac Ciencias, Lima, Peru
[3] Uppsala Univ, Dept Engn Sci, Angstrom Lab, SE-75121 Uppsala, Sweden
[4] Univ Rovira & Virgili, Dept Elect Elect & Automat Engn, ES-43007 Tarragona, Spain