Revealing Structural Disorder in Hydrogenated Amorphous Silicon for a Low‐Loss Photonic Platform at Visible Frequencies

Yang, Younghwan; Yoon, Gwanho; Park, Sunghak; Namgung, Seok Daniel; Badloe, Trevon; Nam, Ki Tae; Rho, Junsuk

doi:10.1002/adma.202005893

Cited by 84 publications

(76 citation statements)

References 55 publications

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“…Furthermore, in order to minimize the absorption of Si in the high frequency visible regime and to increase device efficiency (i.e., to improve the color generation and high hologram efficiency), hydrogenated amorphous silicon (a-Si:H) is deposited using plasma-enhanced chemical vapor deposition at an optimized pressure and temperature, 25 mTorr and 200 °C, respectively (Supplementary Note 4 and Supplementary Fig. 4 ) 48 .The used a-Si:H is denoted as Si(P25) and exhibits much lower extinction coefficient at the wavelength of 532 nm with enough refractive index compared to conventional a-Si, resulting in improved device efficiency (Fig. 2b —Left).…”

Section: Resultsmentioning

confidence: 99%

Pixelated bifunctional metasurface-driven dynamic vectorial holographic color prints for photonic security platform

et al. 2021

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Vectorial holography has gained a lot of attention due to the promise of versatile polarization control of structured light for enhanced optical security and multi-channel optical communication. Here, we propose a bifunctional metasurface which combines both structural color printing and vectorial holography with eight polarization channels towards advanced encryption applications. The structural colour prints are observed under white light while the polarization encoded holograms are reconstructed under laser illumination. To encode multiple holographic images for different polarization states, a pixelated metasurface is adopted. As a proof-of-concept, we devise an electrically tunable optical security platform incorporated with liquid crystals. The optical security platform is doubly encrypted: an image under white light is decrypted to provide the first key and the corresponding information is used to fully unlock the encrypted information via projected vectorial holographic images. Such an electrically tunable optical security platform may enable smart labels for security and anticounterfeiting applications.

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Section: Resultsmentioning

confidence: 99%

Pixelated bifunctional metasurface-driven dynamic vectorial holographic color prints for photonic security platform

et al. 2021

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“…The emitter is a 50 μm‐thick PDMS layer, that is known to have selective emissivity in the AW as a consequence of optical phonon resonance. [ 43 ] The multilayer of a‐Si:H and SiO 2 are fabricated using plasma‐enhanced chemical vapor deposition (PECVD), [ 44 ] followed by spin‐coating of the PDMS (see Section 4). Scanning electron microscopy images show that all six layers are deposited well (Figure 1e).…”

Section: Resultsmentioning

confidence: 99%

Visibly Transparent Radiative Cooler under Direct Sunlight

Kim

Lee

Son

et al. 2021

Advanced Optical Materials

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Transparency is an important characteristic in practical applications of radiative cooling, but the transmitted sunlight trapped in an inner space is generally the main cause of the increasing temperature. A transparent radiative cooler that can lower a temperature during the daytime by transmitting visible light, reflecting near‐infrared (NIR) light, and radiating thermal energy through the atmospheric window is proposed. In contrast to transparent selective emitters that transmit most of the incoming solar irradiance under direct sunlight and opaque radiative coolers that reflect all solar energy, the proposed cooler achieves transparency and the cooling effect simultaneously by selectively blocking solar absorption in the NIR regime. Outdoor rooftop measurements confirm that the cooler can reduce i) the inner temperature of an absorbing system and ii) its own temperature when combined with commercially available paints. During daytime, the cooler provides a temperature reduction of a maximum 14.4 °C and 10.1 °C for the inner and own temperature, respectively, and of an average 5.2 °C and 4.3 °C, respectively, in comparison to the transparent selective emitter. The proposed cooler can reduce the temperature during the daytime while maintaining transparency, confirming its possibilities in practical applications such as passive diurnal cooling of vehicles or buildings and compatibility with current paint technologies for aesthetic use.

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“…Different geometries of meta‐atoms can be researched in innovative ways to produce multiplexed holography and dual‐mode metasurfaces. With the superior functionalities compared to conventional devices, metasurface holography will continue to mature and be able to produce real‐life applications 132–136 such as virtual/augmented reality devices, data storage, and security.…”

Section: Discussionmentioning

confidence: 99%

Geometric and physical configurations of meta‐atoms for advanced metasurface holography

Kim

Yang

Badloe

et al. 2021

InfoMat

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Metasurfaces consisting of subwavelength structures, so‐called meta‐atoms, have steadily attracted considerable attention for advanced holography due to their advantages in terms of high‐resolution holographic images, large field of view, and compact device volume. In contrast to conventional holographic displays using bulky conventional diffractive optical elements, metasurface holography enables arbitrary complex wavefront shaping with a much smaller footprint. In this review, we classify metasurface holography according to the meta‐atom design methodologies, which can further expand hologram functionalities. We describe light‐matter interactions, particularly in metasurface systems, using the relevant the Jones matrix to rigorously explain modulations of the amplitude, phase, and polarization of light. Six different types of meta‐atoms are presented, and the corresponding achievable wavefronts that form the holographic images in the far‐field are also provided. Such a simple classification will give a straightforward approach to design and further realize advanced metasurface holographic devices.

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Revealing Structural Disorder in Hydrogenated Amorphous Silicon for a Low‐Loss Photonic Platform at Visible Frequencies

Cited by 84 publications

References 55 publications

Pixelated bifunctional metasurface-driven dynamic vectorial holographic color prints for photonic security platform

Pixelated bifunctional metasurface-driven dynamic vectorial holographic color prints for photonic security platform

Visibly Transparent Radiative Cooler under Direct Sunlight

Geometric and physical configurations of meta‐atoms for advanced metasurface holography

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