Enhanced surface plasmonic optical absorption engineering of graphene: Simulation by boundary-integral spectral element method

Graphene´s relatively poor absorption is an essential obstacle for designing graphene-based photonic devices with satisfying photo-responsivity. To enhance the tunable light absorption of graphene, appropriate excitation of localized surface plasmon resonance is considered as a promising approach. In this work, the strategy of incorporating periodic cylindrical gold nanoparticle (NP) cluster arrays with Bragg reflectors into graphene-based photodetectors are theoretically studied by the boundary-integral spectral element method (BI-SEM). With the BI-SEM, the models can be numerically analyzed with excellent accuracy and efficiency. Numerical simulation shows that the proposed structures can effectively engineer the light absorption in graphene by tuning plasmon resonance. In the spectra of 300 nm to 1000 nm, a maximum light absorption of 76.13% is observed for the graphene layer with optimal parameters of the photodetector model, while that of 54.68% is observed at the edge of visible spectra.