posted on 2010-06-15, 00:00authored byMelania Paturzo, Anna Pelagotti, Andrea Finizio, Lisa Miccio, Massimiliano Locatelli, Andrea Gertrude, Pasquale Poggi, Riccardo Meucci, Pietro Ferraro
Originally published in Optics Letters on 15 June 2010 (ol-35-12-2112)