Lasers -- Resonators -- Research, Lasers -- Calibration
The properties of a new class of laser resonators are investigated theoretically and experimentally. In these lasers the radiation propagates longitudinally in an annular amplifying medium, and useful low loss modes can be obtained even when the axial region is obscured. Alignment characteristics and far field patterns are discussed, and experiments have been conducted using coaxial double-discharge CO₂ devices.
Lee W. Casperson and M. Shabbir Shekhani, "Mode properties of annular gain lasers," Appl. Opt. 14, 2653-2661 (1975).