Nonlinear pulse propagation and supercontinuum generation in photonic nanowires: experiment and simulation

We investigate theoretically and experimentally the process of supercontinuum generated in sub-wavelength waveguides. We observe experimentally that supercontinuum generated in these photonic nanowires is increasingly blue-shifted from the pump wavelength for decreasing minimum core diameters. We also find the spectral features are sensitive to the specific nanowire profile. Numerical simulations using the nonlinear envelope equation show that accurate modeling requires consideration of the nonlinearity and full dispersion along the entire nanowire profile as well as a wavelength dependent loss. Specifically, the blue-shifting is found to result from an increasing loss for wavelengths larger than the core diameter.