Ultraflat Supercontinuum Spectrum Generated with Soft-Glass Photonic Crystal Fibers

We present some photonic-crystal-fiber structures, made up soft glass, that generate ultrawide (over an octave) and very smooth supercontinuum spectrum when illuminated with femtosecond pulsed light. The design of the fiber geometry in order to reach a nearly ultraflattened normal dispersion behavior is crucial to accomplish the above goals. We recognize that the above supercontinuum sources show high stability and no significant changes are detected even for fairly large fluctuations of the peak power of the incident pulses.