Designs of metareflectors based on nanodisk and annular hole arrays with polarization independence, switching, and broad bandwidth characteristics
Xiaocan Xu, Yu‐Sheng Lin, Rongpeng Fang, Bo‐Ru Yang
Abstract
We propose two tunable metareflectors (MRs) composed of a suspending nanodisk and an annular hole on silicon (Si) substrate with aluminum (Al) mirrors atop. They are denoted as MR-1 and MR-2 for the former and latter, respectively. The proposed MRs exhibit high-efficient cyan-magenta-yellow (CMY) color filtering, and ultrabroad tuning range characteristics. The electromagnetic energy of the resonant wavelength is confined within the suspending nanostructure and bottom Al mirror and then performed a perfect absorption. By changing the height between suspending nanostructure and the bottom Al mirror, MRs exhibit active tuning and single-/dual-resonance switching characteristics spanning the entire visible spectra range. Furthermore, the resonant wavelengths of MRs are sensitive to the surrounding ambient media, which are red-shifted and modulated from single- to dual-resonance by changing the environmental refraction index. The corresponding sensitivities are 500 nm/RIU and 360 nm/RIU for MR-1, 289 nm/RIU and 270 nm/RIU for MR-2, respectively. These results provide an effective strategy for use in high-resolution displays, high-sensitive sensors, optical switches, optical communications, and flexible virtual reality (VR)/augmented reality (AR) applications.