  We demonstrate broadband supercontinuum generation in an all-normal
dispersion polarization-maintaining photonic crystal fiber and we report the
observation of a cross-phase modulation instability sideband that is generated
outside of the supercontinuum bandwidth. We demonstrate this sideband is
polarized on the slow axis and can be suppressed by pumping on the fiber's fast
axis. We theoretically confirm and model this nonlinear process using
phase-matching conditions and numerical simulations, obtaining good agreement
with the measured data.
