Nonlinear Optics in Guided Geometries - Abstract

Bethge, Jens

A chirped photonic crystal fiber for high-fidelity guiding of sub-100 fs pulses

Photonic crystal fibers usually confine the light by means of a periodic cladding, consisting of several layers of identical cells. This design resonantly decreases the transmission losses of such fibers to values of a few dB/km in a narrow wavelength range. However, the rather narrowband transmission bands and the detrimental third order dispersion characteristics of this single-cell design generally render application of such hollow-core fibers difficult in the femtosecond range. Therefore, no fiber-based concept can currently provide guiding of sub-100 fs pulses over extended distances. By introducing a radial chirp into the photonic crystal we here demonstrate a novel concept for photonic crystal fibers that breaks with the paradigm of lattice homogeneity and enables a new degree of freedom in photonic crystal fiber design, eliminating much of the pulse duration restriction of earlier approaches. We demonstrate that the small GVD of chirped photonic crystal fibers allows for surprisingly weak stretching of 13 fs pulses, which only double their duration within 1 m of guided propagation.