Fig. 1. E-shape nantenna configuration: (a) side view and (b) top view.

Fig. 2. Excited SPPs along the arms of the E nantenna illuminated with a plane wave.

Fig. 3. Intensity enhancement at the gap of the proposed E nantenna versus wavelength.

Fig. 4. Electric field intensity distribution along the central x–y plane of the E nantenna with Lx,out=900.0  nm, Ly,out=800.0  nm, Wout=30.0  nm, Lin=550.0  nm, and Win=20.0  nm: (a) λ=2.88  μm and (b) λ=4.41  μm.

Fig. 5. Distribution of the magnetic field component Hz along the central x–y plane of the E nantenna with Lx,out=900.0  nm, Ly,out=800.0  nm, Wout=30.0  nm, Lin=550.0  nm, and Win=20.0  nm: (a) λ=2.88  μm and (b) λ=4.41  μm.

Fig. 6. Capacitive junction coupling between the inner and outer arms.

Fig. 7. S parameters describing the coupling between the inner and outer arms.

Fig. 8. Extinction cross section of the E-nantenna array versus wavelength for different values of the periodicity.

Fig. 9. Intensity enhancement at the nantenna gap versus wavelength for different values of the outer arm horizontal length Lx,out.

Fig. 10. Intensity enhancement at the nantenna gap versus wavelength for different values of the outer arms vertical length Ly,out.

Fig. 11. Intensity enhancement at the nantenna gap versus wavelength for different values of outer arm width Wout.

Fig. 12. Intensity enhancement at the nantenna gap versus wavelength for different values of inner arm length Lin.

Fig. 13. Intensity enhancement at the nantenna gap versus wavelength for different values of inner arm width Win.

Fig. 14. Dual-polarized E nantenna, where the SiO2 layer is drawn semi-transparent for better visibility: (a) side view and (b) top view.

Fig. 15. Intensity enhancement at the two gaps of the proposed dual-polarized nantenna illuminated with normal incident plane waves: (a) y polarized and (b) x polarized.