Graphene Optical Switch Based on Charge Transfer Plasmons

Abstract

In the past decade, dynamic, tunable, compact, and fast plasmonic switches with high modulation depth (MD) and low losses have been developed successfully for various practical applications. Here, using a simple plasmonic dimer consisting of a pair of metallic nanodisks bridged to each other with a graphene monolayer, we develop a highly tunable plasmonic switch for telecommunication applications. We have shown that having active control on the photoconductivity of graphene sheet through electrical bias allows for transition of charges across the atomically thin bridge, giving rise to formation of charge transfer plasmon (CTP) modes. Such an interplay between semiconducting and semi‐metallic states of the graphene sublayer leads to direct control of the excited CTPs. By tuning the peak of CTP at the global telecommunication band (λ = 1550 nm), we designed an integrated, fast, and functional optoelectronic nanoswitch with high MD up to ≈98% and negligible losses. This study presents a promising approach to design tunable, high‐quality, integrated optoelectronic switches for next‐generation advanced nanophotonic applications.