Spatial solitary waves in nondegenerate optical parametric oscillators near an inverted bifurcation

The normal-form equation of a broad-area, triply resonant nondegenerate optical parametric oscillator (OPO) operating near a weakly inverted Hopf bifurcation for signal and idler generation is derived starting from the mean-field model of the OPO equations. It is shown that the spatio-temporal dynamics of the OPO close to the bistability condition may be described by a quintic Ginzburg-Landau equation which in general admits stable motionless solitary waves due to nonvariational effects induced by the different cavity properties for signal and idler fields. Stability of the localized solutions is lost in the degenerate configuration, where signal and idler fields are indistinguishable and nonvariational effects disappear. (C) 1998 Elsevier Science B.V.