Tuning infrared guided-mode resonances with graphene

We report a strategy to modulate the Fano-like signature of a guided-mode resonance supported by a graphenebased grating. The shape of the resonance is controlled by the amount of damping introduced by graphene. A symmetric-To-Asymmetric line shape transition and a significant narrowing of the linewidth occur at relatively moderate levels of chemical potential. Further increases of the chemical potential lead to a blueshift of the Fano resonance due to the modification of the imaginary part of the conductivity of graphene. Our results are supported by a quasi-normal mode analysis of the grating. Using a perturbative approach, we provide analytical expressions for both the resonance wavelength shift and the linewidth modulation induced by changes of the graphene's chemical potential. Electrostatic or electrochemical gating of graphene in the proposed structure provides dynamic control of the Fano-like resonance of the grating, suggesting new opportunities for the design of tunable photonic and optoelectronic devices at infrared wavelengths.