| Summary: | 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 4.468529μm to 4.464453μm 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.
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