AZIMUTHAL MODE-DISCRIMINATION OF ANNULAR RESONATORS

A diffraction formula for annular beam propagation is suggested. Signi ficant computational savings are obtained without restriction to low a zimuthal mode orders. Azimuthal mode discrimination is shown to exist in stable annular resonators. High-order azimuthal modes can suffer lo w diffraction losses with certain mirror parameters. These high-order modes are identified with azimuthal revolving rays that satisfy known geometric relations for multipass resonators.