Fig. 1. Coaxial structure. (a) Overall diagram; (b) longitudinal cross-section of the structure

Fig. 2. Normalized transmission characteristics at different heights

Fig. 3. Electric field distribution in the coaxial aperture x-z plane corresponds to transmission peak value. (a) Electric field at 540 nm peak; (b) electric field at 750 nm peak

Fig. 4. x-y plane electric field distribution of coaxial structure under different light source modes. (a) Horizontal linear polarized light; (b) vertical polarized light; (c) circularly polarized light (levorotation); (d) circularly polarized light (dextrorotation)

Fig. 5. E_z component of horizontal line polarized light. (a) Electric field distribution; (b) Poynting vector

Fig. 6. E_z component electric field distribution and Poynting vector diagrams under circularly polarized light (dextrorotation). (a)(d) Coaxial aperture of 25 nm; (b)(e) coaxial aperture of 40 nm; (c)(f) coaxial aperture of 55 nm

Fig. 7. Distribution of light trapping force and potential well depth in x-y plane under different light source modes. (a) Light trapping force; (b) potential well depth

Fig. 8. Distribution of light trapping force and potential well depth in y-z plane under different light source modes. (a) Light trapping force; (b) potential well depth