Abstract

Supercontinuum (SC) generation in photonic crystal fibers (PCFs) is a cutting-edge phenomenon extensively studied in recent years [1]. SC has found many scientific and technological applications. The control of the SC spectral characteristics is crucial in most of them. A pioneering attempt in this direction was reported in Ref. [2]. We point out that SC is typically generated by accessing the anomalous dispersion regime of the fiber, i.e., when the group velocity dispersion (GVD) coefficient is lower than zero, β₂<0. The recent achievement of soft-glass PCFs, namely, PCFs made up of a transparent material that shows higher nonlinear response than the widely used fused silica, opens new possibilities in SC generation at the normal regime, β₂>0. In this contribution we shift from the anomalous to the normal dispersion regime and this fact allows us to recognize a procedure, based on fiber-dispersion design, to control at least to some extent the spectral characteristics of the broadband SC generated by soft-glass PCFs. As a byproduct, we identify a PCF geometry that provides an ultrawide (over an octave) and very flat SC when pumped with a commercial Er-doped femtosecond fiber laser.

© 2009 IEEE