Complete optical absorption in graphene by using nano-gratings to excite graphene surface plasmons

• Proposing a novel device structure to absorb infrared light.
• Proposing temporal coupled mode theory to model the interaction between light and the device.
• Systematically analyzing the impact of the device parameters on the absorption rate based on temporal coupled mode theory.

Optical absorption enhancements of graphene by exciting graphene surface plasmon waves using nano-gratings are studied. Based on temporal coupled mode theory, we show that the electron relaxation time of graphene and the geometry of the device play crucial roles in determine the absorption rate, and complete optical absorption is possible by adjusting the geometric parameters of the device to match the electron relaxation time of graphene. Moreover, the absorption spectrums can be dynamically tuned by varying the Fermi energy of graphene. Our study could benefit the development of graphene based photonic and optoelectronic devices, such as infrared photodetectors and bolometers.

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