Cheng Z, Seguin H J, Nikumb S K, Seguin V A, Reshef H
Appl Opt. 1988 Mar 1;27(5):836-42. doi: 10.1364/AO.27.000836.
A theoretical investigation of a stable concave-convex resonator configuration, which appears suitable for single-mode high-power energy extraction from large volume gain media, is presented. The design features annular output coupling with a surprisingly uniform near-field intensity distribution. The computer-based analysis, supported by preliminary experimental results, suggests that acceptable alignment tolerances are provided along with an unusually small beam divergence. With proper design, a far-field divergence of 0.5 mrad, encompassing near 80% of the total laser energy, appears feasible. Operational data, recently obtained with this optical extraction approach, have revealed a further important practical advantage over an unstable resonator, being far less prone to mode degradation and hot spot formation on optical component misalignment.
