1. Department of Constructive and Technological Engineering for Lasers and Fibre Optic Communications, National Institute of R&D for Optoelectronics INOE 2000, 409 Atomistilor Street, P.O. Box MG-5, 077125 Magurele, Romania
2. Academic Center for Optical Engineering and Photonics, Faculty of Applied Sciences, University Politehnica of Bucharest, 060042 Bucharest, Romania