Efficient, high-brightness wavelength-beam-combined commercial off-the-shelf diode stacks achieved by use of a wavelength-chirped volume Bragg grating

We report a method of scaling the spatial brightness from commercial off-the-shelf diode laser stacks through wavelength beam combining, by use of a linearly wavelength-chirped volume Bragg grating (VBG). Using a three-bar commercial stack of broad-area lasers and a VBG, we demonstrate 89.5 Wcw of beam-combined output with a beam-combining efficiency of 75%. The output beam has a propagation factor M-2 similar to 26 on the slow axis and M-2 similar to 21 on the fast axis. This corresponds to a brightness of similar to 20 MW/cm(2)sr. To our knowledge, this is the highest brightness broad-area diode laser system. We achieve 81% coupling efficiency into a 100 mu m, 0.22 N.A. fiber. (c) 2006 Optical Society of America.