Light beams with phase singularities in astigmatic square-law waveguides

A beam propagation through astigmatic square-law waveguides (n(x,y) equals Kx2X2 + Ky2Y2) is investigated by theoretical and experimental means. It is shown that if certain condition between astigmatic value, length of waveguide, wave-front curvature and Gaussian parameters takes place then a Hermite-Gaussian beams transforms into Laguerre-Gaussian beams without residual astigmatism.