A Terahertz Multistate Switch and Switchable Filter Utilizing Vanadium Dioxide and Photosensitive Silicon Single-Layer Metamaterial

We present a terahertz (THz) multistate switch and switchable filter utilizing vanadium dioxide and photosensitive silicon single-layer metamaterial (TMSASF). The TMSASF features four states (11, 10, 01, and 00) when THz waves between 0.1 and 4 THz are vertically incident, functioning as a high-performance THz switch with the modulation degrees of amplitude of 100%, where the 11, 10, and 01 states indicate that the switch is ON, while the 00 state indicates that it is OFF. These states correspond to a THz dual-frequency band-pass filter, a THz single-frequency band-pass filters 1, a THz single-frequency band-pass filters 2, and a THz band-stop filter, respectively. The TMSASF can switch among the four states by varying the material’s conductivities, enabling transitions between a THz band-stop filter, a THz single-frequency band-pass filter 2, a THz single-frequency band-pass filter 1, and a THz dual-frequency band-pass filter. For the band-pass filter configurations, the transmittance at the resonant frequencies exceeds 97%, whereas for the band-stop filter configuration, the transmittance within the operating frequency range is 0, indicating high-performance filtering capabilities in all four states. Moreover, when THz waves are vertically incident, the TMSASF demonstrates the properties of being insensitive to polarization. We are confident that this concise device has substantial potential for applications in THz modulation, THz filtering, and future 6G technologies.