Efficiency of dispersive wave generation in dual concentric core microstructured fiber

We describe the generation of powerful dispersive waves that are observed when pumping a dual concentric core
microstructured fiber by means of a sub-nanosecond laser emitting at a wavelength of 1064 nm. The presence of
three zeros in the dispersion curve, their spectral separation from the pump wavelength, and the complex dynamics
of solitons originated by the pump pulse breakup all contribute to boost the amplitude of the dispersive
wave on the long-wavelength side of the pump. The measured conversion efficiency toward the dispersive wave at
1548 nm is as high as 50%. Our experimental analysis of the output spectra is completed by the acquisition of
time delays of the different spectral components. Numerical simulations and an analytical perturbative analysis
identify the central wavelength of the redshifted pump solitons and the dispersion profile of the fiber as the key
parameters for determining the efficiency of the dispersive wave generation process.