Abstract

Rapid development of high power arrayed semiconductor laser diode has generated various applications in the field of optical communications such as optical amplifiers and fiber lasers. Especially rare earth doped clad pumped fiber lasers have taken advantage of compact and high power nature of diode arrays. However the beam parameters of arrayed laser diodes operating at multi-mode are not directly compatible with that of conventional single mode fibers (SMF) allowing only a limited coupling efficiency for direct but-coupling. To overcome these problems double clad fibers have been developed, ^1,2 where the pump beam and signal beam travel in different paths. The pump beam is launched to the inner cladding with a large area and a high numerical aperture (N.A.) instead of the small core.

© 2001 Optical Society of America