▎ 摘　　要

We systematically investigated graphene-based slot and multi-slot waveguides. A tri-slot waveguide which significantly enhances the light-graphene interaction was experimentally demonstrated with low insertion loss. By integrating a dual-layer graphene h-BN heterostructure on the tri-slot waveguide, a high efficiency modulator is designed, which combines the advantages of high modulation efficiency (0.376 dB/mu m), low insertion loss (0.01 dB/mu m), large modulation bandwidth (similar to 0.13 THz) and low power consumption (similar to 0.128 pJ/bit). Our work may promote the development of future high efficient graphene-based optical devices.