Ultra-broadband epsilon-near-zero modulator based on graphene–black phosphorus hybrid structures

Abstract This study presents an ultra-broadband epsilon-near-zero (ENZ) modulator constructed from graphene–black phosphorus hybrid structures. The key mechanism enabling broadband modulation with high modulation depth (MD) is the spectrally complementary ENZ responses of graphene and black phosphorus, where graphene provides a tunable ENZ condition in the visible (VIS) band, while black phosphorus exhibits an anisotropic ENZ response in the near- to mid-infrared (NIR-MIR) regime. Simulation results demonstrate that the proposed modulator functions efficiently over a continuous ENZ-enhanced field-confinement band from 400 nm to 18.63 μ m, spanning the VIS to MIR regions. The MD is significantly enhanced, particularly in the MIR regime due to the induced ENZ effect. In addition, the modulation bandwidth of up to 710 GHz is achieved. Our work highlights the potential to enhance MD across an ultra-broadband spectrum, facilitating future applications of optoelectronic devices that utilize hybridized two-dimensional materials.