Bright-dark vector screening-photovoltaic spatial solitons in biased photorefractive-photovoltaic crystals

We show that the vector beam evolution equations in properly oriented biased photorefractive-photovoltaic crystals can exhibit bright-dark vector solitons, which result from both the bulk photovoltaic effect and the spatially non-uniform screening of the external bias field. By adjusting the polarization of the incident beam to obtain the appropriate ratio of two orthogonal components, these vector solitons can be established. When the bulk photovoltaic effect is negligible, these vector solitons are bright-dark vector screening solitons. When the external field is absent, these vector solitons predict bright-dark vector photovoltaic solitons