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Bragg-induced orbital angular-momentum mixing in paraxial high-finesse cavities

2004; Optica Publishing Group; Volume: 29; Issue: 23 Linguagem: Inglês

10.1364/ol.29.002788

1539-4794

David Foster, Jens U. Nöckel,

Plasmonic and Surface Plasmon Research

Numerical calculation of vector electromagnetic modes of plano-concave microcavities reveals that the polarization-dependent reflectivity of a flat Bragg mirror can lead to unexpected cavity field distribution for nominally paraxial modes. Even in a rotationally symmetric resonator, certain pairs of orbital angular momenta are necessarily mixed in an excitation-independent way to form doublets. A characteristic mixing angle is identified, which even in the paraxial limit can be designed to have large values. This correction to Gaussian theory is of zeroth order in deviations from paraxiality. We discuss the resultant nonuniform polarization fields. Observation will require small cavities with sufficiently high Q. Possible applications are proposed.