Abstract: The propagation properties of two incoherent coupled beams in lossy media are investigated. The evolution equations of amplitude, distance, phase and propagation velocity of incoherently coupled beams with dielectric loss are derived by variational method, then the interaction potential energy and interaction force of two spatial optical solitons are obtained, and the effect of dielectric loss on soliton transmission and interaction is analyzed. It is shown that the dielectric loss slows down the phase change of the soliton, and the loss also makes the interaction of solitons decay exponentially with the propagation distance, while long-distance transmission may lead to the collapse of soliton pairs. It is also shown that the interaction between solitons has a maximum, and when the distance between solitons is greater than a certain value, the two solitons will transmit independently without interference.

Key words: nonlinear optics, spatial optical soliton, variational principle, incoherently coupled, loss