Eigenmodes of a Symmetric Cylindrical Confocal Laser Resonator and Their Perturbation by Output-Coupling Apertures

Fox and Li1 demonstrated by numerical iteration that modes in the sense of self-reproducing field patterns exist for open Fabry-Perot resonators. Using a numerical technique which is different from that of Fox and Li and which is more suitable than iteration for the analysis of high-order modes, we have calculated the diffraction losses and the field distributions at the reflectors of the low-loss modes of a symmetric cylindrical confocal resonator for Fresnel numbers 0.6 ^ Nm ^ 2.0. The results are discussed below. An axial section of the symmetric confocal resonator under examination is illustrated in Fig. 1. The cavity is bounded at each end by identical spherical (parabolic) mirrors whose perfectly reflecting surfaces extend over the annular region a0 ^ p ^ am . While a comparison of 333 334 T H E BELL SYSTEM T E C H N I C A L J O U R N A L , F E B R U A R Y 1