Generation of a vector doughnut beam from an internal mirror He-Ne laser

We demonstrate the direct generation of a vector doughnut mode from an internal mirror He-Ne laser using the spot defect method. A circular-shaped spot defect of ∼30 μm in diameter with low reflectivity created on the inner surface of a cavity mirror by laser ablation suppressed the oscillation of a Gaussian beam resulting in the oscillation of a doughnut beam. Polarization investigation showed that the generated beam was a vector hybrid mode.