Presentation + Paper
19 September 2018 High efficient metasurface for broadband achromatic focusing in visible spectrum
Author Affiliations +
Abstract
Metasurfaces are expected to realize the miniaturization of conventional refractive optics into planar structures; however, they suffer from large chromatic aberration due to the high phase dispersion of their subwavelength building blocks, limiting their real applications in imaging and displaying systems. In this paper, a high-efficient broadband achromatic metasurface (HBAM) is designed and numerically demonstrated to suppress the chromatic aberration in the continuous visible spectrum. The HBAM consists of TiO2 nanofins as the metasurface building blocks (MBBs) on a layer of glass as the substrate, providing a broadband response and high polarization conversion efficiency for circularly polarized incidences in the desired bandwidth. The phase profile of the metasurface can be separated into two parts: the wavelength -independent basic phase distribution represented by the Pancharatnam-Berry (PB) phase, depending only on the orientations of the MBBs, and the wavelength-dependent phase dispersion part. The HBAM applies resonance tuning for compensating the phase dispersion, and further eliminates the chromatic aberration by integrating the phase compensation into the PB phase manipulation. The parameters of the HBAM structures are optimized in finite difference time domain (FDTD) simulation for enhancing the efficiency and achromatic focusing performance. Using this approach, this HBAM is capable of focusing light of wavelengths covering the entire visible spectrum (from 400 nm to 700 nm) at the same focal plane with the spot sizes close to the diffraction limit. The minimum polarization conversion efficiency of most designed MBBS in such spectrum is above 20%. This design could be viable for various practical applications such as cameras and wearable optics.
Conference Presentation
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Chang Wang, Rengmao Wu, Siqi Liu, Xiao Tao, Wentao Zhang, Chenning Tao, Shengqian Chang, Peng Sun, Xu Liu, and Zhenrong Zheng "High efficient metasurface for broadband achromatic focusing in visible spectrum", Proc. SPIE 10719, Metamaterials, Metadevices, and Metasystems 2018, 107192F (19 September 2018); https://doi.org/10.1117/12.2319566
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KEYWORDS
Phase compensation

Polarization

Phase shifts

Chromatic aberrations

Diffraction

Finite-difference time-domain method

Imaging systems

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