Plasmonic-Based Subwavelength Graphene-on-hBN Modulator on Silicon Photonics

Optical modulators are essential components in optical communication and photonic neuromorphic networks. Graphene on silicon waveguides have been proposed for optical modulation but the modulation depth is limited to 0.1 dB/μm. Higher modulation depth and shorter modulators can be achieved with plasmonic modes; however, due to its transverse magnetic nature, they weakly interact with graphene. In this contribution, a plasmonic Bloch mode supported by a plasmonic waveguide is used to overcome this problem. Its high in-plane electric field strongly interacts with graphene. Numerical results show modulation depths of 4 dB/μm at 1.65 μm with 2.6 dB loss. A subwavelength footprint of 0.5 μm2 allows a modulation speed of up to 39 GHz and an energy consumption of 21.2 fJ/b. This sub-λ size modulator is a promising candidate for optical communication and neuromorphic circuits.