SPATIAL SOLITARY WAVES IN NONDEGENERATE OPTICAL PARAMETRIC OSCILLATORS NEAR AN INVERTED BIFURCATION

The normal-form equation of a broad-area, triply resonant nondegenerat e 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 s patio-temporal dynamics of the OPO close to the bistability condition may be described by a quintic Ginzburg-Landau equation which in genera l admits stable motionless solitary waves due to nonvariational effect s induced by the different cavity properties for signal and idler fiel ds. Stability of the localized solutions is lost in the degenerate con figuration, where signal and idler fields are indistinguishable and no nvariational effects disappear. (C) 1998 Elsevier Science B.V.