Fig. 1. Cross section of waveguides based on three graphene-coated dielectric nanowires with non-coplanar axis. The black rings on the outside of the dielectric nanowires are graphene

Fig. 2. Field distributions of five modes at f=35 THz,ρ0=ρ1=100 nm,ρ2=50 nm,a=175 nm,b=60 nm, and EF=0.5 eV

Fig. 3. Dependency of (a) real part of the effective refractive index and (b) propagation length on the operating frequency f

Fig. 4. Distributions of electric field of mode 1 when the operating frequency f is (a) 31 THz and (b) 39 THz at ρ0=ρ1=100 nm,ρ2=50 nm,a=175 nm,b=60 nm, and EF=0.5 eV

Fig. 5. Dependency of (a) real part of the effective refractive index and (b) propagation length on the radius ρ2

Fig. 6. Distributions of electric field of mode 1 when the radius ρ2 of the nanowire 2 is (a) 25 nm and (b) 55 nm at ρ0=ρ1=100 nm,f=35 THz,a=175 nm,b=60 nm, and EF=0.5 eV

Fig. 7. Dependency of (a) real part of effective refractive index and (b) propagation length on height b

Fig. 8. Distributions of electric field of mode 1 when the height b is (a) 10 nm and (b) 100 nm at ρ0=ρ1=100 nm,ρ2=50 nm,f=35 THz,a=175 nm, and EF=0.5 eV

Fig. 9. Dependency of (a) real part of effective refractive index and (b) propagation length on space a

Fig. 10. Distributions of electric field of mode 1 when the space a is (a) 160 nm and (b) 195 nm at ρ0=ρ1=100 nm,ρ2=50 nm,f=35 THz,b=60 nm, and EF=0.5 eV

Fig. 11. Dependency of (a) real part of effective refractive index and (b) propagation length on Fermi energy EF

Fig. 12. Distributions of electric field of mode 1 when the Fermi energy EF is (a) 0.4 eV and (b) 0.8 eV at ρ0=ρ1=100 nm,ρ2=50 nm,f=35 THz,a=175 nm, and b=60 nm

Fig. 13. Comparison of propagation length of mode 1 of the waveguide with coplanar axis and the waveguide with non-coplanar axis. (a) Frequency; (b) radius of the middle nanowire; (c) distance between two nanowires in the horizontal direction; (d) Fermi energy

Fig. 14. Electric field distribution of (a) waveguide with coplanar axis and (b) waveguide with non-coplanar axis when ρ2=40 nm