Fig. 1. Diagram of metamaterial structure, and top view of unit cell. (a) Diagram of metamaterial structure; (b) top view of unit cell

Fig. 2. Reflectance spectra of graphene dimer, single graphene disk, and graphene trimer. Chemical potential of graphene is 1 eV and spacing of graphene disks is 0.8 μm

Fig. 3. Electric field distributions and current distributions at specific positions. (a) M1； （b） M3； （c） M2

Fig. 4. Influence of graphene trimer spacing on Fano resonance with grapheme chemical potential of 1.1 eV

Fig. 5. Reflection spectra of graphene trimer for different chemical potential, and variation in resonance frequency shift with chemical potential of graphene. (a) Reflection spectra of graphene trimer for different chemical potential; (b) variation in resonance frequency shift with chemical potential of graphene

Fig. 6. Reflection spectra of graphene trimer and resonance frequency shift. Graphene chemical potential is fixed at 1 eV and spacing of grapheme disks is 0.8 μm. (a) Reflection spectra of graphene trimer for different refractive index of analyte; (b) variation of resonance frequency shift with refractive index of analyte when thickness of analyte is 500 nm

Fig. 7. Reflection spectra for different thickness of analyte when refractive index of analyte is 1.4， and relationship between resonance frequency shift and thickness of analyte. (a) Reflection spectra for different thickness of analyte when refractive index of analyte is 1.4; (b) resonance frequency shift versus thickness of analyte