Dielectric waveguides with embedded graphene nanoribbons for all-optical broadband modulation

All-optical processing offers low power consumption and fast operation speed and is a promising approach to high-bit-rate communication. Realization of all-optical integrated photonics requires core materials that strongly mediate photon–photon interaction. Recently, it was shown that, in the long-wavelength limit, graphene nanoribbons (GNRs) have a very strong Kerr optical nonlinearity in the telecom wavelength range (1.3−1.6ðoe‡m). We propose a dielectric waveguide with embedded GNRs for all-optical self-amplitude-modulation applications. By implanting a van der Waals (vdW) heterostructure consisting of GNRs and hexagonal boron nitride into a rib silicon waveguide, we maximize the optical concentration near the GNRs and enhance nonlinear optical effects. Different-width GNRs incorporated in the vdW heterostructure provide strong self-sustaining broadband modulation over the telecom frequency range, without a need for dynamical tuning. The compact footprint and self-sustaining, broad-bandwidth saturable absorption make the proposed device a suitable component for ultrafast nanophotonic applications.