▎ 摘　　要

Graphene has generated exceptional interest as an optoelectronic material(1,2) because its high carrier mobility(3,4) and broadband absorption(5) promise to make extremely fast and broadband electro-optic devices possible(6-9). Electro-optic graphene modulators previously reported, however, have been limited in bandwidth to a few gigahertz(10-15) because of the large capacitance required to achieve reasonable voltage swings. Here, we demonstrate a graphene electro-optic modulator based on resonator loss modulation at critical coupling(16) that shows drastically increased speed and efficiency. Our device operates with a 30 GHz bandwidth and with a state-of-the-art modulation efficiency of 15 dB per 10 V. We also show the first high-speed large-signal operation in a graphene modulator, paving the way for fast digital communications using this platform. The modulator uniquely uses silicon nitride waveguides, an otherwise completely passive material platform, with promising applications for ultra-low-loss broadband structures and nonlinear optics.