Fig. 1. (a) Top view of one unit cell of the symmetry-broken Si disk array used for THz switching. (b) Cross-sectional view of the investigated structure. The black arrow indicates the THz radiation while the lightning symbol stands for the optical pump.

Fig. 2. (a) The solid blue line represents numerically calculated transmission spectrum for THz radiations normally propagating through the symmetry-broken Si disk array, while the dotted line is for the spectrum through a solid Si disk array for comparison. (b) An enlarged part of the transmission spectrum close to the sharp resonance. (c) Magnitude profile for the magnetic field (Hz) and the vectorial distribution for the electric field. (d) Transmission spectrum when the air slot is rotated by 90° while keeping its center unchanged. The inset illustrates the geometry.

Fig. 3. Numerically calculated eigen frequencies of the unit cell when the horizontal wave vectors are set as k_x = k_y = 0 for different geometry parameters: (a) L is fixed at 24 μm while W changes; (b) W is fixed at 4 μm while L changes.

Fig. 4. Photocarrier density at the pump laser power density of 76 μW/cm² and the corresponding Si refractive index (real part) along the thickness of the Si layer. z = 0 is the bottom of the Si layer.

Fig. 5. (a) Transmittance at 1.143 THz at different power of the pump laser. (b) Transmission spectrum for two cases, when there is no pump laser (blue solid line) and when the pump laser power density is 127 μW/cm² (red dashed line).