Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles

Abstract Optical films and surfaces using geometric phase are increasingly demonstrating unique and sometimes enhanced performance compared to traditional elements employing propagation phase. Here, we report on a diffraction grating with wider angular bandwidth and significantly higher average firs...

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Autores principales:	Xiao Xiang, Jihwan Kim, Michael J. Escuti
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2018
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/5dafae0639944dab87fad338086ad190
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spelling	oai:doaj.org-article:5dafae0639944dab87fad338086ad1902021-12-02T11:41:03ZBragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles10.1038/s41598-018-25535-02045-2322https://doaj.org/article/5dafae0639944dab87fad338086ad1902018-05-01T00:00:00Zhttps://doi.org/10.1038/s41598-018-25535-0https://doaj.org/toc/2045-2322Abstract Optical films and surfaces using geometric phase are increasingly demonstrating unique and sometimes enhanced performance compared to traditional elements employing propagation phase. Here, we report on a diffraction grating with wider angular bandwidth and significantly higher average first-order efficiency than the nearest prior art of metasurfaces, volume holographic gratings, and surface-relief gratings configured to achieve a steep deflection angle. More specifically, we demonstrate a liquid crystal (LC) polymer Bragg polarization grating (PG) with large angular bandwidth and high efficiency in transmission-mode for 532 nm wavelength and 400 nm period. Angular bandwidth was significantly increased by arranging two slanted grating layers within the same monolithic film. First, we studied the optical properties with simulation and identified a structure with 48° angular bandwidth and 70% average first-order efficiency. Second, we fabricated a sample using a photo-aligned chiral nematic LC, where the two grating slants were controlled by the chiral dopants. We measured 40° angular bandwidth, 76% average efficiency, and 96% peak efficiency. Strong input polarization sensitivity (300:1 contrast) and spectral bandwidth (200 nm) mostly matched prior PGs. This approach is especially advantageous for augmented-reality systems and nonmechanical beam steering.Xiao XiangJihwan KimMichael J. EscutiNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 8, Iss 1, Pp 1-6 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Xiao Xiang Jihwan Kim Michael J. Escuti Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
description	Abstract Optical films and surfaces using geometric phase are increasingly demonstrating unique and sometimes enhanced performance compared to traditional elements employing propagation phase. Here, we report on a diffraction grating with wider angular bandwidth and significantly higher average first-order efficiency than the nearest prior art of metasurfaces, volume holographic gratings, and surface-relief gratings configured to achieve a steep deflection angle. More specifically, we demonstrate a liquid crystal (LC) polymer Bragg polarization grating (PG) with large angular bandwidth and high efficiency in transmission-mode for 532 nm wavelength and 400 nm period. Angular bandwidth was significantly increased by arranging two slanted grating layers within the same monolithic film. First, we studied the optical properties with simulation and identified a structure with 48° angular bandwidth and 70% average first-order efficiency. Second, we fabricated a sample using a photo-aligned chiral nematic LC, where the two grating slants were controlled by the chiral dopants. We measured 40° angular bandwidth, 76% average efficiency, and 96% peak efficiency. Strong input polarization sensitivity (300:1 contrast) and spectral bandwidth (200 nm) mostly matched prior PGs. This approach is especially advantageous for augmented-reality systems and nonmechanical beam steering.
format	article
author	Xiao Xiang Jihwan Kim Michael J. Escuti
author_facet	Xiao Xiang Jihwan Kim Michael J. Escuti
author_sort	Xiao Xiang
title	Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
title_short	Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
title_full	Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
title_fullStr	Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
title_full_unstemmed	Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
title_sort	bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
publisher	Nature Portfolio
publishDate	2018
url	https://doaj.org/article/5dafae0639944dab87fad338086ad190
work_keys_str_mv	AT xiaoxiang braggpolarizationgratingsforwideangularbandwidthandhighefficiencyatsteepdeflectionangles AT jihwankim braggpolarizationgratingsforwideangularbandwidthandhighefficiencyatsteepdeflectionangles AT michaeljescuti braggpolarizationgratingsforwideangularbandwidthandhighefficiencyatsteepdeflectionangles
_version_	1718395462258524160

Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles

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