Quadratic solitons resulting from double-resonance wave mixing

The existence and stability of three-wave solitons, both (1 + 1) and (2 + 1 ) dimensional, that result from a double-resonance (type I plus type II) pa rametric interaction in a purely quadratic nonlinear medium are investigate d. We demonstrate the existence of a family of stable solitons for a broad parameter range in the double-resonance model. Further, these solitons exhi bit multistability, a property that is potentially useful for optical switc hing applications. We introduce a way to measure the quality of multistabil ity and use this measure to compare the double-resonance model with single- resonance models in chi ((2)) media. We also discuss the modulational insta bility of the double-resonance system and present physical estimates of the power required for soliton generation. (C) 2000 Optical Society of America [S0740-3224(00)00312-X] OCIS codes: 190.5530, 190.1950, 190.4410.