Two-dimensional bright spatial solitons stable over limited intensities and ring formation in polydiacetylene para-toluene sulfonate.

Spatial soliton formation in the bulk single-crystal polydiacetylene para-toulene sulfonate has been studied experimentally. The unique nonlinearity of this material at 1600??nm leads to stable solitons below an intensity maximum, and for higher intensities the input beams form a ring and a soliton.