Fiber-Coupled Kilowatt Diode Laser Pumps Produce 800 Watts of Fiber Laser Output

Bodo Ehlers¹, Falk Doerfel¹, Stefan Heinemann¹, Chi-Hung Liu², Almantas Galvanauskas²

¹ Fraunhofer USA, Inc., Center for Laser Technology   46025 Port Street, Plymouth, MI 48170

² University of Michigan, Center for Ultra Short Optical Sciences 1301 Beal Avenue, Ann Arbor, MI 48109

Abstract High power fiber-coupled diode laser modules have been developed for pumping of fiber lasers. Each of the laser modules provides up to 500 Watts of output power out of the fiber operating at one wavelength. Spectral beam combining of these pumps scales the power into the kilowatts out of one multimode fiber. Several of these fiber-coupled pumps are spectrally combined and used for two-sided pumping of Yb-doped fiber lasers. A large mode area double clad fiber is used with a core diameter of 20 mm core. This set-up produces a near diffraction limited fiber laser output of more than 800 watts. Mode discrimination is achieved by coiling of the active fiber.