Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we present the evolution equations of one-dimension incoherently coupled spatial soliton families due to two-photon effect in biased photorefractive crystals with both the linear and quadratic electro-optic effect and discuss their existence conditions and properties in detail. Our analysis indicates that these soliton families can exist in all three possible realizations: dark-dark, bright-bright and dark-bright provided that the incident beams have the same polarization, wavelength and are mutually incoherent. Finally, the stabilities of these soliton families have been discussed by means of beam propagation methods.

we report on the generation of cascaded four-wave mixing (CFWM) in a photonic crystal fiber with a high peak power picosecond pulse pumping in the normal dispersion region and a weak continuous wave seeded. We also experimentally investigate the dependence of CFWM bandwidth on the seeding wavelengths. Experimental results demonstrate the existence of optimum seeding wavelengths for broadband CFWM even though the pulse wavelength is 50 nm shorter than the zero dispersion wavelength. And CFWM products spanning more than 300 nm are experimentally obtained.