MEMS Tunable Metasurfaces Based on Gap Plasmon or Fabry-Perot Resonances

Tunable metasurfaces promise to enable adaptive optical systems with complex functionalities. Among possible realizations, a recent platform combining microelectromechanical systems (MEMS) with gap-surface plasmon (GSP) metasurfaces offers high modulation efficiency, broadband operation, and fast response. We compare tunable metasurfaces operating in GSP and Fabry-Perot (FP) regions by investigating polarization-independent blazed gratings both numerically and experimentally. Peak efficiency is calculated to be similar to 75% in both cases (similar to 40% in measurements), while the operation bandwidth is found larger when operating in the GSP region. Advantages of operating in the FP region include relaxed assembly requirements and operation tolerances. Additionally, simulation and experimental results show that coupling between neighboring unit cells increases for larger air gaps, resulting in deteriorated efficiency. We believe the presented analysis provides important guidelines for designing tunable metasurfaces for diverse applications in miniaturized adaptive optical systems.

Automated summary

Tunable metasurfaces combined with microelectromechanical systems (MEMS) and gap-surface plasmon (GSP) offer high modulation efficiency, broadband operation, and fast response. A comparison between tunable metasurfaces operating in GSP and Fabry-Perot (FP) regions shows that GSP region provides larger operation bandwidth, while FP region offers relaxed assembly requirements and operation tolerances.