Absorption and Self-Calibrated Sensing Based on Tunable Fano Resonance in a Grating Coupled Graphene/Waveguide Hybrid Structure

A grating coupled graphene surface plasmon and planar waveguide structure is investigated. A sharp asymmetric profile Fano resonance attributed by the coupling between the graphene plasmon and the waveguide mode can be observed. The physical origin of Fano resonance are analyzed by electric field distribution, and the tunable Fano resonances with different line profiles are demonstrated by varying the Fermi level and the incident angle. The further studies demonstrate the Fano resonance has a potential application in light absorption and the absorption can reach 76% when graphene carrier mobility is 0.5 m2/(Vs). In addition, the Fano resonance could potentially be applied as a self-referenced refractive index sensor due to the decoupled property of Fano resonance and a sensitivity of 5.21 μm/RIU can be achieved. Thus, the Fano resonance we proposed in the work would have great prospects in developing excellent light absorption and refractive index sensor functional devices.