▎ 摘　　要

The rapid development of highly integrated photonic circuits has been driving electro-optic (EO) devices to increasingly compact sizes, with the perspective of being able to control light at the nanoscale. However, tunability with spatial resolution below 10 nm scale with conventional approaches, such as metallic nanowires, remains a challenge. Here, we show a graphene-coated nanowire system aiming at beam spatial modulation at a deeply subwavelength scale. By analytically and numerically investigating the eigenmodal properties of this system, we found that beam power can propagate along either a swinging or a helical path in the hybrid nanowire. In particular, the period of the swing beam and the chirality and period of the helix beam can be flexibly controlled by tuning the chemical potential of graphene via the gate voltage. Significantly, due to its good modal confinement, such a beam can be independently manipulated even in the presence of another nanowire at a separation of 40 nm, which opens a realistic path toward gate programmable EO addressing or data storage with ultrahigh density (64 terabyte/mu m). At the same time, by fulfilling the phase matching condition between the two supported guided modes operating at different wavelengths, either a full band or band tunable terahertz wave at the nanoscale may be achieved by nonlinear difference frequency generation. Our proposed hybrid nanowire system opens interesting potentials to accomplish gate-programmable EO devices at sub-10 nm scale.