Curved-Rim Open Resonators

Field configurations and resonant frequencies are analytically derived for some low-loss modes of a Fabry-Perot (FP) open resonator having curved rims along the edges. Since the low-loss modes are limited by a caustic surface, the problem can be simply treated by neglecting the diffraction due to the finite dimensions of the mirrors. The results are compared with those obtained by numerically solving the integral equation of the open cavity.