Nonlinear optics: Supercontinuum generation in sub-centimeter lengths of high-nonlinearity photonic crystal fibers

The nonlinear transformation of ultrafast laser pulses into supercontinuum (SC) in sub-centimeter lengths of high-nonlinear photonic crystal fibers (PCF) was investigated. The PCF that was used to generate SC, provide bandwidth in excess of one optical octave with limits imposed by the physical properties of the fiber itself. The experiment was performed in high-nonlinearity soft-glass. The SC produced was smooth and broad, spanning from 350 nm to beyond 3000 nm. The spectral quality of the SC radiation spectrum was altered by selecting an appropriate length of PCF. Significant spectral smoothing was observed in a region with no soliton fission and high-order nonlinearity effect. It was observed that when the fiber length was shorter than the dispersion length, soltion propagation was not important and a symmetric SC spectrum arises from self-phase modulation.