Bandwidth-tunable absorption enhancement of visible and near-infrared light in monolayer graphene by localized plasmon resonances and their diffraction coupling

Bandwidth-tunable light absorption enhancement in monolayer graphene is practically important for graphenebased photoelectric devices. Especially, it is still a huge challenge to achieve high-efficiency graphene absorption with extremely narrow sub-nanometer bandwidth much smaller than one nanometer. In this work, both broadband and narrowband absorption peaks of monolayer graphene are numerically achieved in visible and near-infrared wavelength ranges. The broadband absorption peak is ascribed to localized dipolar plasmon resonances in individual silver nanodisks, and the narrowband absorption peak arises from collective first-order diffraction coupling effect in periodic array of silver nanodisks. By changing the array period, the full width at half maximum (FWHM) of the broadband absorption peak can vary from 100 nm to 50 nm. Correspondingly, the FWHM of the narrowband absorption peak is tuned from about 6.4 nm to only 0.25 nm, thus realizing an ultra-narrow sub-nanometer bandwidth.

Automated summary

In this work, both broadband and narrowband absorption peaks are achieved in monolayer graphene by introducing periodic arrays of silver nanodisks. The broadband absorption peak is attributed to localized dipolar plasmon resonances in individual silver nanodisks, while the narrowband absorption peak arises from collective first-order diffraction coupling effect. The full width at half maximum (FWHM) of the broadband absorption peak can be varied from 100 nm to 50 nm by changing the array period, and the FWHM of the narrowband absorption peak can be tuned from about 6.4 nm to only 0.25 nm, realizing an ultra-narrow sub-nanometer bandwidth.