Unstable optical resonator with cancelling edge waves

摘要

A structural improvement to the feedback (i.e., output) mirror of an unstable optical resonator. The improvement may comprise either a step-like projection (either convex or concave) on the internal surface of the feedback mirror, or a change in curvature of the internal surface of the mirror. Each of these improvements actually constitutes a discontinuity in the internal surface of the mirror, with the curvature of the mirror on either side (i.e., around) the improvement remaining the same. The improvement cancels the interfering edge waves at the geometric source point of the resonator, thereby minimizing the effect of edge diffraction, and results in yielding more "geometric" modes having relatively uniform intensity profiles and large differences in feedback ratios between the dominant and higher-order modes.