Solitary Waves in Chains of High-Index Dielectric Nanoparticles

We study both linear and nonlinear propagation of pulses in waveguides composed of high-index dielectric nanoparticles supporting both electric and magnetic resonances. We reveal that short pulses (100 fs) broaden significantly in the linear regime after propagating only several tens of micrometers, due to a strong waveguide dispersion. In the nonlinear regime, the pulses propagating in the chains of spherical nanoparticles broaden even more strongly than in the linear regime due to defocusing nonlinearity. However, for the chains of nanodisks the pulse broadening can be compensated by the nonlinear effect, due to the interplay of the electric and magnetic resonances that can change the sign of the group-velocity dispersion for some frequencies, making possible the formation and propagation of solitary waves and effective generation of the new frequencies. Our results demonstrate that considered systems can serve as a promising platform for nonlinear and ultrafast nanophotonics, allowing the observation of strong nonlinear effects at the micrometer scales.