Steady-state dark (bright)spatial solitons are predicted for biased photovoltaic photorefractive materials,which are due to the photovoltaic effect and spatially nonuniform screening of the external bias field. These solitons differ from previously observed steady-state photorefractive spatial solitons in their properties and physical origin.If the applied field is strong enough, these solitons are just like the screening solitons. If the applied field is absent, these solitons degenerate into the photovoltaic solitons under the close-circuit condition.
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