▎ 摘　　要

We report a tunable ultra-narrowband mid-infrared absorber with graphene and dielectric metamaterials. At the graphene Fermi level of 0.2 eV in the mid-infrared regime, the absorber has an absorption bandwidth of 0.033 nm which is at least one order of magnitude smaller than those reported with graphene in the mid-infrared regime. In addition, by changing the graphene Fermi level from 0.2 eV to 0.6 eV, the absorption peaks of the absorber can be shifted from 4.468529 mu m to 4.464453 mu m with bandwidth less than 0.05 nm in the tuning Fermi level range. The simulation results of electromagnetic field distribution show that the guided-mode resonance occurs at the resonance absorption peak. As a thermal source, the corresponding spatial coherence length is 212.4 mm. The tunable ultra-narrowband mid-infrared absorption characteristics indicate that our absorber has the potential applications in the tunable coherent emission of thermal source and the tunable filtering.