Second-harmonic generation with zero group-velocity mismatch in Nonlinear photonic crystal fibers

We consider an index-guiding silica photonic crystal fiber with a triangular hole-pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative size of the holes, second-harmonic generation with zero group-velocity mismatch is found to be feasible for any fundamental wavelength above 780 nm. The phasevelocity mismatch has a lower limit with coherence lengths in the micron range. The nonlinear strength is optimized when the fundamental has maximum confinement in the core. The conversion bandwidth allows for fs-pulse conversion and 4-180 %/(W(.)cm(2)) relative efficiencies were found.