Formation of Ince-Gaussian modes in a stable laser oscillator

Ince-Gaussian modes form a complete family of exact and orthogonal solutions of the paraxial wave equation for elliptical coordinates. The transverse distribution of these fields is described by the Ince polynomials and have an inherent elliptical symmetry. These modes constitute a smooth transition from Hermite-Gaussian modes to Laguerre-Gaussian modes. We report the experimental observation of Ince-Gaussian modes directly generated in a stable resonator. By slightly breaking the symmetry of the cavity of a diode pumped Nd:YVO4 laser and its pump beam configuration we were able to generate single high order Ince Gaussian modes with very high quality. The observed transverse modes and nodal patterns have the proposed elliptic structure and exhibit remarkable agreement with the theoretical predictions.