Fig. 1. (a) Schematic diagram of the chiral plasmonic lens. (b) Structural parameters (up) and single unit cell with two slits (down). (c) FDTD simulated result of SPP field in the xy plane excited by the chiral plasmonic lens. Two layers of the structure are used to enhance the SPP field. (d) FDTD simulated result of the SPP field excited by a single semicircular slit with 100 nm width and radius R = 4 µm. (e), (f) The analytical model results corresponding to (c), (d). In (c)–(f), the order of CVB is m = 3, and the incident angle θ = 0°.

Fig. 2. (a)–(c) Polarization distribution (black arrows) of CVB with m = −2, 1, and 3, and the corresponding (d)–(f) SPP field is excited by the above three CVBs. The white line indicates the center position (x = 0). (g) The SPP focal field profile in the x axis with different order m. (h) The relationship between SPP focal position in the x axis and the CVB order m.

Fig. 3. (a)–(c) SPP field excited by the CVB with different incident angle θ. The white line indicates the center position (x = 0). (d) The SPP focal field profile in the x axis with different incident angle θ. (e) The relationship between SPP focal position in the x axis and the incident angle θ.

Fig. 4. (a) Schematic diagram of waveguide focus coupling. (b), (c) Influence of SPP focus position on waveguide coupling (the white line is the waveguide area, and the result in the figure is P_y). (d) Normalized transmission of the waveguide at different CVB orders and different incident angles. (e) The linear relationship corresponding to the peak point in (d).