1 Instituto de Fisica, Universidade Federal de Goias, Av. Esperanca 1533, Campus Samambaia, Goiania, GO, 74690-900, Brazil
2 Department of Electrical Engineering, Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-ville, Montreal, QC, H3C 3A7, Canada
3 Department of Engineering Physics, Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-ville, Montreal, QC, H3C 3A7, Canada
4 Centre d'Optique, Photonique et Laser, 2375 Rue de la Terrasse, Universite Laval, Quebec, QC, G1V 0A6, Canada
