We report the experimental demonstration of a method that allows the simultaneous frequency-doubling and the shaping of a light beam into a variety of patterns. The technique is based on the controllable generation of multiple-vortex patterns in seeded schemes. Our observations were performed under conditions of second-harmonic generation pumped by picosecond pulses at 1055 nm, but the scheme can be extended to all parametric processes.
Molina, G., Minardi, S., Bramati, A., Di Trapani, P., Torner, L. Demonstration of vortex-induced beam shaping in seeded SHG. "Optics express", Juliol 2001, vol. 9, núm. 2, p. 110-115.