Inversion of a guided optical vortex A. V. Carpentier, H. Michinel, J. R. Salgueiro, S. Doval and A. Ferrando J. Eur. Opt. Soc.-Rapid Publ., 1 (2006) 06031 Published online: 18 December 2006 DOI: 10.2971/jeos.2006.06031