Beam reshaping by use of spatial solitons in the quadratic nonlinear medium KTP.

We have demonstrated the transformation of elliptical beams into cylindrically symmetric beams through the formation of quadratic spatial solitons. By use of type II phase-matched second-harmonic generation in a KTP crystal, input elliptical beams with aspect ratios as large as 8:1 were propagated through the KTP crystal, and they exited the crystal as a cylindrically symmetric beam. The threshold for soliton formation and the power throughput were measured versus ellipticity.