Fabry-Perot Resonator with Circular Apertures

A resonator with circular apertures at the centers of the parallel-plane circular mirrors is studied. The approach is a modification of the foregoing analysis by the authors. The mode and the diffraction loss are obtained from the complex-frequency which gives a source-free field distribution. The loss is represented in terms of the Fresnel numbers of the mirrors and the apertures. The field distributions are calculated for the several lowest-order modes. The loss of a resonator with infinite strip mirrors is derived from the limiting case of the above result. Furthermore, the diffraction loss of a resonator with a single aperture is also obtained, which gives an increase of about 20 percent compared with the case of two apertures.