Abstract
Dielectric metasurfaces have opened promising possibilities to enable a versatile platform in the miniaturization of optical elements at visible and infrared frequencies. Due to high efficiency and compatibility with CMOS fabrication technology, silicon-based metasurfaces have a remarkable potential for a wide variety of optical devices. Adding tunability mechanisms to metasurfaces could be beneficial for their application in areas such as communications, imaging and sensing. In this paper, we propose an all-silicon reconfigurable metasurface based on the concept of glide symmetry. The reconfigurability is achieved by a phase modulation of the transmitted wave activated by a lateral displacement of the layers. The misalignment between the layers creates a new inner periodicity which leads to the formation of a metamolecule with a new sort of near-field interaction. The proposed approach is highly versatile for developing multifunctional and tunable metadevices at optical frequencies. As a proof of concept, in this paper, we design a bifunctional metadevice, as well as a tunable lens and a controllable beam deflector operating at 1.55 μm.
Highlights
Metasurfaces are a two-dimensional version of metamaterials composed of metallic and/or dielectric sub-wavelength elements called metaatoms
It has been demonstrated that silicon metaatoms as constitutional elements enhance the efficiency of metasurfaces at infrared wavelengths and can be fabricated in one lithographic step. They are compatible with complementary metal oxide semiconductor (CMOS) technology[7,8]
Glide symmetry is proposed to tailor the spectral position of the resonance frequency and control the phase response of metasurfaces at optical frequencies
Summary
Metasurfaces are a two-dimensional version of metamaterials composed of metallic and/or dielectric sub-wavelength elements called metaatoms. Fast, continuous and real-time tuning, reconfigurable metasurfaces based on MEMS/ NEMS have been recently studied[24,31,32,47] The reconfigurability via these technologies is activated by changing the shape of the metaatoms and/or relocating the position of two separated metasurfaces[48,49]. Glide symmetry is proposed to tailor the spectral position of the resonance frequency and control the phase response of metasurfaces at optical frequencies. The displacements between the layers manipulate the near-field interaction between the metaatoms and modifies the spectral position of the excited resonances in the metamolecule. This technique is capable of providing a selective sub-wavelength phase modulation of the transmitted wave through the structure. In the proposed metamolecule, apart from Mie multipoles, another family of resonance, toroidal dipole, has been excited due to the existence of the near-field interaction among metaatoms[55]
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