Spatial solitons supported by competing nonlinearities in double-period QPM-structures

Steffen Kjær Johansen

Department of Informatics and Mathematical Modelling, Building 321, Technical University of Denmark, 2800 Kongens Lyngby, Denmark

Abstract: It is well-known that quasi-phase-matching (QPM) gratings on average induce Kerr-like nonlinearities in quadratic media. However, the influence of these cubic nonlinearities on soliton formation in actual physical setups is vanishing. This is due to the dependence on the grating period which normally is engineered to compensate a very large phase-mismatch effectively eliminating cubic terms. We report on numerical experiments in QPM-structures with a superimposed slow second period. We show theoretically that these structures effectively can be engineered to mimic a one-period structure at small phase-mismatches making soliton formation and control supported by competing nonlinearities practically realizable.