▎ 摘　　要

Si3N4 has emerged as a prominent material for expanding the capability of silicon photonics to wavelengths below < 1 mu m. However, realizing an efficient optical modulator, a key building block for any integrated optics platform, remains a major challenge in Si3N4 mainly because this material has a vanishing Pockels coefficient. Here, we propose a compact Si3N4 based optical modulator by using a thin VO2 layer on top of a Si3N4 strip waveguide where amplitude modulation is achieved via phase transition of the VO2 layer. To reduce the actuation time of the temperature-induced VO2 phase transition, a mono-layer graphene microheater is designed for the active Si3N4VO2 waveguide. Our simulations indicate a high extinction ratio of similar to 8.28 dB/mu m with an insertion loss of similar to 2.8 dB/mu m at the design wavelength of 850 nm for the proposed modulator and wideband operation in the wavelength range of 800-900 nm. It is shown that employing the electrical and thermal properties of graphene not only leads to a significant reduction of the power consumption of the device but also, decreases the actuation time compared to previous modulators based on the thermal phase transition of the VO2.