Tracking spatial modes in nearly hemispherical microcavities

We measure experimentally the spatial intensity profiles and resonant frequencies of the transverse modes of nearly hemi-spherical microcavities with cavity length and mirror curvatures below 10 mum. These resonators possess axially-symmetric Gauss-Laguerre-like modes, but do not display the frequency degeneracies typical of large-scale optical cavities. It is possible to interpret these results using a paraxial model of cavity propagation that includes non-parabolic optical elements.