▎ 摘　　要

Optical switches based on dielectric nanostructures are highly desired at present. To enhance the wavelength-selective light absorption, and achieve an absorption-induced switching effect, here we propose a graphene-based metamaterial absorber that consists of a dielectric grating, a graphene monolayer, and a photonic crystal. Numerical results reveal that the dual-band absorption with an ultranarrow spectrum of the system is enhanced greatly due to the critical coupling, which is enabled by the combined effects of guided mode resonances and photonic band gap. The quality factor of the absorber can achieve a high value (>500), which is basically consistent with the coupled mode theory. Slow light emerges within the absorption window. In addition, electrostatic gating of graphene in the proposed structure provides dynamic control of the absorption due to the change of the chemical potential of the graphene, resulting in an optional multichannel switching effect. Unlike other one-dimensional devices, these effects can be applied to another polarization without changing the structure parameters, and the quality factor is significantly enhanced (>1000). The tunable light absorption offered by the simple structure with an all-dielectric configuration will provide potential applications for graphene-based optoelectronic devices in the near-infrared range, such as narrowband selective filters, detectors, optical switches, modulators, slow optical devices, etc. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement