Electrically dynamic terahertz phase modulator with high transmittance based on a Huygens' metasurface

The phase shifts of dynamic terahertz (THz) phase modulators based on transmissive metasurfaces are usually limited to within 180^∘, which is a necessary amount to perform efficient terahertz wavefront modulation. Few works exhibit a phase shift larger than 200^∘ but with a transmittance less than 3% during modulation. To address this challenge, a dynamic terahertz phase modulator using a dislocation-introduced dual-layer Huygens' metasurface (HM) with embedded vanadium dioxide (VO₂) is proposed. This compact design uniquely combines high transmittance with a large phase shift in broadband. Key achievements include a maximum dynamic phase shift of 281^∘ at 0.64 THz with a transmittance greater than 50% both before and after a current stimulus. An operational bandwidth where the co-polarization phase shift exceeds 180^∘ is 32.3% under normal incidence. And the bandwidth where the phase shift is larger than 180^∘ and transmittance higher than 50% simultaneously achieves 10.4% from 0.64 THz to 0.71 THz. This innovative dual-layer HM approach efficiently balances the performance of dynamic terahertz phase modulators, opening new possibilities for dynamic terahertz wavefront manipulation devices and providing technical support for terahertz spatial light modulators and terahertz holographic projectors.