The evolution of light pulses and beams in a quasi-phase-matched (QPM) quadratic medium is usually described by considering only the spatial harmonic of the QPM grating that minimizes the residual phase-mismatch. I show that, for strongly phase-mismatched interactions (the cascading regime), several harmonics need to be accounted for in order to obtain the correct value of the effective cubic nonlinearity, for which I find a simple analytical expression. I discuss the effects of the higher order harmonics of the grating on solitary wave propagation.
© 2014 Optical Society of America
Original Manuscript: January 14, 2014
Revised Manuscript: February 28, 2014
Manuscript Accepted: March 16, 2014
Published: April 10, 2014
Matteo Conforti, "Exact cascading nonlinearity in quasi-phase-matched quadratic media," Opt. Lett. 39, 2427-2430 (2014)