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Optical metasurfaces based on dielectric Mie-resonators were established as an efficient platform for realizing a multitude of optical functionalities. Recently, tunable optical dielectric metasurfaces have attracted increased research interest, and various tunable dielectric metadevices have been demonstrated. Infiltrating dielectric metasurfaces with nematic liquid crystals (LCs) represents an efficient and convenient tuning approach [1], which is compatible with established LC industrial technologies. Here we demonstrate two electrically tunable LC-infiltrated dielectric metasurfaces working at near-infrared and visible wavelengths, respectively. We demonstrate that the metasurfaces can be electrically tuned into and out of the so-called Huygens’ regime of spectrally overlapping electric and magnetic dipolar resonances by application of an external voltage. For the first time to our knowledge, we have utilized a LC photoalignment material [2] to realize LC-tunable metasurface devices with drastic improvement of their tuning performance and reproducibility. In particular, we demonstrate tuning of the metasurface transmission from nearly opaque to nearly transparent at 1070 nm. Furthermore, we demonstrate a switchable silicon transmissive display with 53% contrast, operating in the visible spectral range. Finally, we propose a novel route toward phase-only tuning by applying simultaneous electrical and thermal stimuli to the LC-infiltrated dielectric Huygens’ metasurfaces. In our numerical simulations, we observe 178° phase modulation with a transmittance exceeding 64% over the entire tuning range at 1078 nm wavelength.
[1] A. Komar et al., Appl. Phys. Lett. 110(7), 071109 (2017).
[2] I. I. Rushnova et al., Opt. Commun. 413, 179-183 (2018).
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