The evolution of fundamental beams into quadratic spatial solitons was investigated in a periodically poled bulk KTiOPO4 crystal near and at phase matching. Various soliton properties, such as trapping efficiency as a function of phase mismatch, poling-induced walk-off, and the effects of pulse width, beam width, and input beam quality, were measured. Effects attributed to the presence of cubic nonlinearities were also observed.
Kim, H., Jankovic, L., Stegeman, G., Carrasco, S., Torner, L., Eger, D., Katz, M. Quadratic spatial solitons in periodically poled KTiOPO4. "Optics letters", Abril 2003, vol. 28, núm. 8, p. 640-642.