Multimode squeezed states produced by a confocal parametric oscillator K. I. Petsas, A. Gatti, L. A. Lugiato and C. Fabre Eur. Phys. J. D, 22 3 (2003) 501-512 Published online: 11 February 2003 DOI: 10.1140/epjd/e2003-00045-5