Wideband sub-THz half-wave plate using 3D-printed low-index metagratings with superwavelength lattice

High-index dielectric metasurfaces are rarely reported around 0.1-0.3 THz, as an extremely large etching depth is needed according to the millimeter-scale wavelength. In this work, we propose an easy solution to sub-THz wideband polarization control by utilizing 3D-printed low-index (n~1.5) metagrat...

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Bibliographic Details
Published in:Optics express 2019-01, Vol.27 (1), p.202-211
Main Authors: Dong, Xi-Pu, Cheng, Jie-Rong, Fan, Fei, Xu, Shi-Tong, Wang, Xiang-Hui, Chang, Sheng-Jiang
Format: Article
Language:English
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Summary:High-index dielectric metasurfaces are rarely reported around 0.1-0.3 THz, as an extremely large etching depth is needed according to the millimeter-scale wavelength. In this work, we propose an easy solution to sub-THz wideband polarization control by utilizing 3D-printed low-index (n~1.5) metagratings. The metagrating with subwavelength lattice is shown as a very efficient half-wave plate (net polarization conversion of 87%) at 0.14 THz but showing noisy spectrum. The design with superwavelength lattice offers a smooth and wide bandwidth for linear polarization rotation. Study of the mechanism shows that the lattice size slightly above wavelength is a better choice for the low-index metadevice as it maintains high efficiency in the zero diffraction order and wide bandwidth due to the small mode dispersion. Such designs offer a feasible solution especially suitable for sub-THz polarization and phase control, complementary to the existing high-index dielectric and metallic metasurfaces.
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.27.000202