1. Department of Physics and it’s Teaching Methods, Armenian State Pedagogical University after Kh. Abovyan, Yerevan 0010, Armenia
2. Chaire Photonique, Laboratoire Matériaux Optiques Photonique et Systèmes (LMOPS), CentraleSupélec, F-57070 Metz, France
3. Dipartimento di Fisica e Astronomia, Università di Padova, 35131 Padova, Italy