  We demonstrate a uniform high spectral brightness and peak power density
all-fiber supercontinuum source. The source consists of a nanosecond Ytterbium
fiber laser and an optimal length PCF producing a continuum with a peak power
density of 2 W/nm and less than 5 dB of spectral variation between 590 to 1500
nm. The Watt level per nm peak power density enables the use of such sources
for the characterization of nonlinear materials. Application of the source is
demonstrated with the characterization of several periodically poled crystals.
