Microtopography-Guided Double-Layer Cross Structure for a Terahertz Multiband Amplitude Modulator

Terahertz (THz) modulator can be used to modulate the amplitude and frequency of THz wave. A THz multiband amplitude modulator based on temperature control is proposed in this study. The metamaterial structure of proposed modulator is a double-layer cross structure which attached on a silicon substrate, and the cross-distribution of different materials in top and middle layer is Cu @ SiO₂ and SiO₂ @ VO₂, respectively. To prepare the modulator, a microtopographic substrate-guided method with low-cost and high accuracy capacities is proposed. Finally, the proposed modulator exhibits above 70% transmittance in 1.31–1.36 THz, 1.55–1.60 THz, and 1.76–1.79 THz, respectively, at 35 °C After temperature rises to 70 °C, transmittance decreases below 0.1 in 1–2 THz. The similarity of the experimental and simulated transmission is up to 85.67%, and the mean modulation depth (MD) is 0.73. The performance can fulfill the applications in THz amplitude modulator, and due to the large modulation depth of transmission, the proposed modulator can be used as a filter switch. It also indicates the proposed method can be effectively applied in other multilayer composite materials preparation.