Tunable dual-band mid-infrared absorber based on the coupling of a graphene surface plasmon polariton and Tamm phonon-polariton.

We propose and demonstrate a tunable dual-band mid-infrared absorber structure based on the coupling effect of a surface plasmon polariton (SPP) and Tamm phonon-polariton (TPhP). The structure is composed of the distributed Bragg reflector (DBR), air layer, SiC and graphene ribbons. In the air layer, the graphene ribbons are embedded to realize the localized SPP (LSPP), which makes the structure support both the graphene LSPP (GLSPP) and TPhP. The absorption properties of the structure are investigated theoretically and numerically. It is found that strong coupling of the GLSPP and TPhP can be realized by choosing reasonable parameters, which causes a dual-frequency perfect absorption and makes the maximum Rabi splitting of the coupled mode reach 5.76 meV. Furthermore, the mode coupling and absorption intensity can be tuned by adjusting the thickness of the air layer and the Fermi level of the graphene ribbons. This work might provide new possibilities for the development of mid-infrared band sensors, filters and emitters based on the coupling of multiple modes.