Abstract

Diode laser pumped fiber lasers become important as high power light sources. The design of the refractive index profile and doping distribution of high power laser fibers has to meet several requirements: 1) a large entrance area and a high numerical aperture to match the high beam parameter product of high power pump sources, i.e. diode laser arrays, 2) an effective transfer of pump power to excited states in the active material to allow for a short resonator length, 3) a high brightness by a small beam parameter product of the generated laser radiation. These requirements led to a variety of fiber designs, i.e. circular and offset double clad and M-proftle fibers (cf. Fig. 1) [1,2].

© 1998 IEEE