Deflection angle switching with a metasurface based on phase-change nanorods [Invited]

Choi, Chanjoong; Kim, Sun-Je; Yun, Jeong-Geun; Sung, Jaeyong; Lee, Seung‐Yeol; Lee, Byoungho

doi:10.3788/col201816.050009

Cited by 11 publications

(1 citation statement)

References 30 publications

(34 reference statements)

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“…In contrast to conventional optical devices, metasurfaces have great freedom to manipulate the amplitude, wavefront, and polarization state of light. Mutation on the critical surface in contact with air is the basic principle for realizing the function of metasurface, such as deflecting, 2 – 5 lens, 6 – 8 and achromatic 3 , 9 , 10 . Due to its sub-wavelength size, low loss, simple design, high utilization, easy integration, and negative refractive index, metasurface has gradually attracted the attention of researchers.…”

Section: Introductionmentioning

confidence: 99%

Design of the achromatic vortex metalens based on phase change material with two-layer two-phase modulation

Luo,

Bai,

et al. 2023

Opt. Eng.

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Section: Introductionmentioning

confidence: 99%

Design of the achromatic vortex metalens based on phase change material with two-layer two-phase modulation

Luo,

Bai,

et al. 2023

Opt. Eng.

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Hybrid State Engineering of Phase‐Change Metasurface for All‐Optical Cryptography

Choi

Mun

Sung

et al. 2020

Adv Funct Materials

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Chalcogenide material Ge2Sb2Te5 (GST) has bistable phases, the so‐called amorphous and crystalline phases that exhibit large refractive index contrast. It can be reversibly switched within a nanosecond time scale through applying thermal bias, especially optical or electrical pulse signals. Recently, GST has been exploited as an ingredient of all‐optical dynamic metasurfaces, thanks to its ultrafast and efficient switching functionality. However, most of these devices provide only two‐level switching functionality and this limitation hinders their application to diverse all‐optical systems. In this paper, the method to expand switching functionality of GST metasurfaces to three level through engineering thermo‐optically creatable hybrid state that is co‐existing state of amorphous and crystalline GST‐based meta‐atoms is proposed. Furthermore, the novel hologram technique is introduced for providing the visual information that is only recognizable in the hybrid state GST metasurface. Thanks to thermo‐optical complexity to make the hybrid state, the metasurface allows the realization of highly secured visual cryptography architecture without the complex optical setup. The phase‐change metasurface based on multi‐physical design has significant potential for applications such as all‐optical image encryption, security, and anti‐counterfeiting.

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A Highly Efficient Bifunctional Dielectric Metasurface Enabling Polarization‐Tuned Focusing and Deflection for Visible Light

Gao

Park

Choi

2019

Advanced Optical Materials

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A multifunctional metasurface has attracted drastically growing interest, serving as a prominent candidate to cope with both device miniaturization and integration. Conventional transmissive bifunctional metasurfaces working for visible light inherently suffer from several demerits owing to the use of geometric phase and spatial multiplexing scheme. Research endeavors have been mainly devoted to the implementation of a static device. In this work, a highly efficient bifunctional dielectric metasurface, taking advantage of a unit cell (UC) the building block of which capitalizes on a nanopost in hydrogenated amorphous silicon, is proposed and experimentally demonstrated to successfully enable polarization-mediated anomalous beam deflection and focusing in the visible band. Through the tailoring of the UC periodicity, we are capable of efficiently tuning the beam deflection angle and focusing distance. For the fabricated sample, the normal transverse-electric incidence within a spectral band from 600 nm to 715 nm is angle-resolved to a single diffraction order via the beam deflection, while a bright line focus is attained at the target focal plane for the normal transverse-magnetic incidence at  = 650 nm. This work will initiate a positive prospect for the development of highperformance tunable multifunctional metasurfaces.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

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Deflection angle switching with a metasurface based on phase-change nanorods [Invited]

Cited by 11 publications

References 30 publications

Design of the achromatic vortex metalens based on phase change material with two-layer two-phase modulation

Design of the achromatic vortex metalens based on phase change material with two-layer two-phase modulation

Hybrid State Engineering of Phase‐Change Metasurface for All‐Optical Cryptography

A Highly Efficient Bifunctional Dielectric Metasurface Enabling Polarization‐Tuned Focusing and Deflection for Visible Light

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