Bifocal Metalens with Diverse Polarization Combination
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Bifocal Metalens with Diverse Polarization Combination Yuansheng Han1 · Xiaoqing Lu1 · Haoran Lv1 · Zhen Mou1 · Changda Zhou1 · Shuyun Teng1 Received: 17 July 2020 / Accepted: 13 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract One compound metalens with the multiple functions is benefit to the optical integration. A bifocal metalens with diverse polarization combination is proposed by using the optical metasurface. This metalens consists of nanometer rectangular holes etched on a silver film. Two focusing spots result respectively from the propagation phase introduced by nanoholes with different sizes and the geometric phase caused by the rotation of nanoholes. Two focal spots for one designed compound metalens take on different polarization combination under different polarization light illumination. The interference between them is effectively controlled through the ingenious design. Theoretic analysis and calculation simulations give the powerful verification for the diverse polarization combination of the bifocal matelens. This focusing metalens with diverse polarization combination can expand the wide applications of metalenses. Keywords Metasurface · Metalens · Nanostructure · Polarization-selective device
Introduction Metasurface points to the two-dimensional metamaterial, and it consists of periodic nanometer scatterers with subwavelength separation. Because of ultra-thin thickness and powerful light control capability, metasurface has been applied to design compact optical devices [1–6]. Metalens is a kind of metasurface device that acts as a lens with the focusing and imaging functions [7–9]. As we know, the common lens works on basis of the refraction or diffraction effect; therefore, its volume is usually bulky. The lens with high numerical aperture or possessing special function often needs complex design. Metalens has the characteristics of sub-wavelength thickness, effective focusing, and high numerical aperture; therefore, it behaves the wide application prospects in optical integration and optical micro-manipulation. The precondition for the beam focusing is the in-phase interference of light fields. The different phases of the fields from the metasurface units to the focal spot should be offset. * Shuyun Teng [email protected] 1
Shandong Provincial Key Laboratory of Optics and Photonic Device & Shandong Provincial Engineering and Technical Center of Light Manipulations & School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
The optical metasurface can shape the wave front of light through introduce geometric phase resulting in the rotation of anisotropic nanoscatterers [10–12] or the propagation phases coming from nanoscatterers with different sizes and different shapes [13–15]. Among the applications of geometric phase delay, the illumination polarization is usually chosen as the circular polarization because the geometric phases are always accompanied by the circular polarization transformation [11, 16]. Relati
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