Multifield Controlled Terahertz Modulator Based on Silicon‐Vanadium Dioxide Hybrid Metasurface

Abstract

AbstractDespite flourishing and deepening trend in the terahertz (THz) field, there are still challenges in high‐performance active system components, such as THz modulators. Present THz modulators are typically limited to a single external driving field and the fixed switching speed, hindering the ability to flexibly manipulate THz waves. Here, an optically and thermally controlled THz modulator based on silicon (Si) and vanadium dioxide (VO2) hybrid metasurface is proposed to overcome these limitations. The modulator enables the dynamical control of the transmitted amplitude in the range of 0.4–1.8 THz. Under thermal management, a maximum modulation depth (MD) of 97.2% at 0.9 THz can be acquired, thanks to the phase transition of VO2. Once excited with an 800 nm pump light at 1600 µJ cm−2, the device achieves a maximum MD of 91.5% at 0.87 THz accomplished with an ultrafast speed of 2 ps, resulting from photogenerated carriers in the Si substrate. Furthermore, the findings of this study propose a promising strategy for developing multifield controlled active THz components, which would be a new paradigm to design switchable metasurface devices.