Fig. 1. Model diagrams. (a) Nanoantenna array and its Cartesian coordinate system; (b) front view of a unit of nano antenna when P_x=500 nm, P_y=340 nm, l_x=480 nm, and l_y=70 nm

Fig. 2. Linear simulation results. (a) Simulated absorption, reflection, and transmission of nano antennas at normal incidence; (b) magnetic field and current density distributions in x-y plane; (c) magnetic field distribution in x-z plane

Fig. 3. Nonlinear simulation results. (a) Time domain signal of electric field of incident pulse; (b) transmitted time-domain signal of nano optical antenna along y direction; (c) frequency-domain signal of antenna obtained by Fourier transformation from transmitted time-domain signal along y direction; (d) time-domain THz signal of antenna after low pass filtering from signal from transmitted time-domain signal along y direction

Fig. 4. Simulation results under excitation of incident light with different pulse widths. (a) Time-domain terahertz signals excited by incident light with different pulse widths (0.06-0.14 ps); (b) terahertz spectra excited by incident light with different pulse widths (0.06-0.14 ps)

Fig. 5. Simulation results under excitation of incident light with different polarization angles. (a) THz spectra excited by incident light with different polarization angles (0°-90°); (b) polarization angle dependence of THz wave