187 W, 3.7 mJ from spectrally combined pulsed 2 ns fiber amplifiers

We report on a spectral combination of four 2 ns pulsed fiber amplifier systems to a total output power of 187 W at a 50 kHz repetition rate resulting in >3.7 mJ of pulse energy and 1.7 MW of pulse peak power. A dielectric reflection grating is used to merge the four individual beams to one output with close to diffraction-limited beam quality independent of the power level. The output characteristics are beyond the capabilities of a single emitter and further scaling in a straightforward way appears to be feasible. (C) 2009 Optical Society of America