Low Insertion Loss Plasmon-Enhanced Graphene All-Optical Modulator

[Image: see text] Graphene has emerged as an ultrafast optoelectronic material for all-optical modulators. However, because of its atomic thickness, it absorbs a limited amount of light. For that reason, graphene-based all-optical modulators suffer from either low modulation efficiencies or high switching energies. Through plasmonic means, these modulators can overcome the aforementioned challenges, yet the insertion loss (IL) of plasmon-enhanced modulators can be a major drawback. Herein, we propose a plasmon-enhanced graphene all-optical modulator that can be integrated into the silicon-on-insulator platform. The device performance is quantified by investigating its switching energy, extinction ratio (ER), IL, and operation speed. Theoretically, it achieves ultrafast (<120 fs) and energy-efficient (<0.6 pJ) switching. In addition, it can operate with an ultra-high bandwidth beyond 100 GHz. Simulation results reveal that a high ER of 3.5 dB can be realized for a 12 μm long modulator, yielding a modulation efficiency of ∼0.28 dB/μm. Moreover, it is characterized by a 6.2 dB IL, which is the lowest IL reported for a plasmon-enhanced graphene all-optical modulator.