Tunable Spectrum Selective Enhanced Absorption of Monolayer Graphene in Fano Resonant Waveguide Grating with four-Part Period

Spectral responses of a novel resonant waveguide grating (WGG) configuration, in which monolayer graphene is prepared on top of the WGG, and the period is composed of two grating ridges with identical width are presented. Fano-like resonance can effectively improve the graphene absorption from 2.3 to 63.2 %. And the absorption width can be tailored without modifying the spectral lineshapes and sideband levels, while the maximum absorption wavelength linearly varies with the increase of period. The situation of oblique incidence is studied as well. Fano-like resonant grating suggests a new opportunity for the design of tunable graphene photonic and optoelectronic devices.