Switchable active phase modulation and holography encryption based on hybrid metasurfaces

Zhou, Hongqiang; Wang, Yongtian; Li, Xiaowei; Wang, Qing; Wei, Qunshuo; Geng, Guangzhou; Huang, Lingling

doi:10.1515/nanoph-2019-0519

Cited by 50 publications

(27 citation statements)

References 46 publications

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“…The design and optimization of metasurfaces for unconventional functionalities has led to several new optical meta-devices for control over propagation of electromagnetic (EM) waves at sub-wavelength scale [1][2][3][4][5] . The constituent nanostructures of a metasurface are typically meta-atoms and meta-molecules that are designed for various light modulation applications 6,7 .…”

Section: Moreover the Non-uniqueness Of Structural Designs And High mentioning

confidence: 99%

A cyclical deep learning based framework for simultaneous inverse and forward design of nanophotonic metasurfaces

Mall

Patil

Sethi

et al. 2020

Sci Rep

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The conventional approach to nanophotonic metasurface design and optimization for a targeted electromagnetic response involves exploring large geometry and material spaces. This is a highly iterative process based on trial and error, which is computationally costly and time consuming. Moreover, the non-uniqueness of structural designs and high non-linearity between electromagnetic response and design makes this problem challenging. To model this unintuitive relationship between electromagnetic response and metasurface structural design as a probability distribution in the design space, we introduce a framework for inverse design of nanophotonic metasurfaces based on cyclical deep learning (DL). The proposed framework performs inverse design and optimization mechanism for the generation of meta-atoms and meta-molecules as metasurface units based on DL models and genetic algorithm. The framework includes consecutive DL models that emulate both numerical electromagnetic simulation and iterative processes of optimization, and generate optimized structural designs while simultaneously performing forward and inverse design tasks. A selection and evaluation of generated structural designs is performed by the genetic algorithm to construct a desired optical response and design space that mimics real world responses. Importantly, our cyclical generation framework also explores the space of new metasurface topologies. As an example application of the utility of our proposed architecture, we demonstrate the inverse design of gap-plasmon based half-wave plate metasurface for user-defined optical response. Our proposed technique can be easily generalized for designing nanophtonic metasurfaces for a wide range of targeted optical response.

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Section: Moreover the Non-uniqueness Of Structural Designs And High mentioning

confidence: 99%

A cyclical deep learning based framework for simultaneous inverse and forward design of nanophotonic metasurfaces

Mall

Patil

Sethi

et al. 2020

Sci Rep

View full text Add to dashboard Cite

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“…Chiral meta-holograms are also introduced for direction-dependent holographic encoding [38][39][40] . Other encoding methods relying on incident wavelength 41 , nonlinear effect 42 , spatial frequency 43 , orbital angular momentum 44,45 and tunable metasurface 46,47 are also demonstrated. Note that all of these proposed multiplexing metaholograms encode information on the intensity of the holographic images.…”

Section: Introductionmentioning

confidence: 99%

Broadband Decoupling of Intensity and Polarization with Vectorial Fourier Metasurfaces

Song

Baroni

et al. 2021

Preprint

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Intensity and polarization are two fundamental components of light. Independently control of them is of tremendous interest in many applications. In this paper, we propose a general vectorial encryption method, which enables arbitrary far-field light distribution with the local polarization, including orientations and ellipticities, decoupling intensity from polarization across a broad bandwidth using geometric phase metasurfaces. By revamping the well-known iterative Fourier transform algorithm, we propose “à la carte” design of far-field intensity and polarization distribution with vectorial Fourier metasurfaces. A series of non-conventional vectorial field distribution, mimicking cylindrical vector beams in the sense that they share the same intensity profile but with different polarization distribution and a speckled phase distribution, is demonstrated. Vectorial Fourier optical metasurfaces may enable important applications in the area of complex light beam generation, secure optical data storage, steganography and optical communications.

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“…Metasurfaces, a two-dimensional modality of metamaterials, have received extensive attention owing to their extraordinary capabilities to control amplitude, phase, and polarization of electromagnetic waves flexibly . Among fascinating applications, metasurface hologram is receiving growing interests since fabrication of numerous subwavelength meta-atoms on a large aperture effectively eliminates undesired diffraction orders and thus provides unprecedented resolution for constructed images compared to traditional holograms based on spatial light modulators which may suffer from low resolution, small viewing angles, and undesired high-order diffractions [28][29][30][31][32][33][34][35][36][37]. The marriage of computer-generated hologram and the metasurface platform further opens a bright avenue to construct multifunctional holographic system with exceptional image qualities.…”

Section: Introductionmentioning

confidence: 99%

A large field-of-view metasurface for complex-amplitude hologram breaking numerical aperture limitation

Zheng

et al. 2020

Nanophotonics

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Owing to the potential to manipulate simultaneously amplitude and phase of electromagnetic wave, complex-amplitude holographic metasurfaces (CAHMs) can achieve improved image-reconstruction quality compared with amplitude-only and phase-only ones. However, prevailing design methods based on Huygens–Fresnel theory for CAHMs, e.g., Rayleigh–Sommerfeld diffraction theory (RSDT), restrict acquisition of high-precision reconstruction in a large field of view (FOV), especially in the small numerical aperture (NA) scenario. To this end, a CAHM consisting of Sine-shaped meta-atoms is proposed in a microwave region, enabled by a novel complex amplitude retrieval method, to realize large FOV holograms while breaking the large NA limitation. Calculations and full-wave simulations demonstrate that the proposed method can achieve superior-quality holograms, even for nonparaxial holograms in a relatively small NA scenario, thus improving FOV and aperture utilization efficiency of CAHMs. The reconstruction comparison of a complex multi-intensity field distribution between CAHM prototypes designed by our method and by RSDT further confirms this point. We also compare both theoretically and experimentally the CAHM by our method with the phase-only metasurface by weighted Gerchberg–Saxton algorithm. Superior-quality holograms with suppressed background noise and relieved deformation, promised by the extra amplitude manipulation freedom, is witnessed. Finally, due to its wavelength irrelevance, the proposed method is applicable to the entire spectrum, spanning from microwave to optics.

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Switchable active phase modulation and holography encryption based on hybrid metasurfaces

Cited by 50 publications

References 46 publications

A cyclical deep learning based framework for simultaneous inverse and forward design of nanophotonic metasurfaces

A cyclical deep learning based framework for simultaneous inverse and forward design of nanophotonic metasurfaces

Broadband Decoupling of Intensity and Polarization with Vectorial Fourier Metasurfaces

A large field-of-view metasurface for complex-amplitude hologram breaking numerical aperture limitation

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