Fig. 1. (a) Schematic of the biosensor based on graphene plasmonics and (b) the temporal coupled theory description of the coupling among the incident light, reflected light and the device.

Fig. 2. (a) Calculated GPs mode pattern when Λ=200  nm and W=100  nm and (b) reflection spectra with sensing medium change from air to cell protein (n=1.37) and to double-stranded DNA (n=1.53).

Fig. 3. (a) Simulated reflection spectra with varying τ when T=800  nm. (b) Resonant reflectance and FWHM extracted from the reflection spectra with varying τ. (c) Calculated FOM as a function of τ.

Fig. 4. (a) Simulated reflection spectra with varying T when τ=0.8  ps. (b) Resonant reflectance and FWHM extracted from the reflection spectra with varying T. (c) Calculated FOM as a function of T.

Fig. 5. (a) Reflectance mapping with varying wavelength of incident light and Fermi energy level when T=400  nm and τ=0.8  ps. (b) The extracted reflection spectra with varying Fermi energy level of graphene from 0.2 to 0.6 eV. (c) Comparison of the FOM of the reflection-type and the transmission-type biosensors with varying Fermi energy level.

Fig. 6. Comparison of the FOM of the reflection-type and the transmission-type biosensors with varying width (a) for a fixed Λ=200  nm and period (b) for a fixed occupation ratio of 50%.