One type of high order coupled photovoltaic spatial solitons

By numerical simulation we theoretically study one type of high order coupled photovoltaic spatial solitons that can be realized by using four parallel beams with two different frequency components in photovoltaic crystals whose light-induced refractive index perturbation is positive. The numerical results show that this kind of coupled soliton can be approached by hyperbolic secant beams under some suitable conditions. The optical steering properties of such a high order coupled soliton are investigated. It is shown that such a coupled soliton cannot be realized when the incident beams remarkably deviated from the lateral symmetry.