A fiber-coupled laser is proposed for an internal mirror type system, in which the fiber is directly connected to the coupling-hole of a resonator mirror by taking exact matching of their diameters each other. This is, on trial, experimentally demonstrated for a CO2 laser combining with a KRS-5 fiber, obtaining the peak power up to 3 watts with the KRS-5 fiber having the diameter of 1 mm in a conventional compact laser. The theoretical estimates for optimum design is also described, especially on the optimum coupling of a mirror in hemispherical configuration. Furthermore, advantages of the proposed scheme are discussed.
"Fiber-coupled CO2 Laser For Medical Use", Proc. SPIE 0576, Optical Fibers in Medicine and Biology I, (14 January 1986); doi: 10.1117/12.950736; https://doi.org/10.1117/12.950736