RESUMO
Metasurface based polarization multiplexing is usually conducted in two orthogonal-polarization states, e.g., linearly polarized along x/y axes, left/right-handed circularly polarized states, etc. Herein, we show metasurfaces can be employed to implement tri-channel polarization multiplexing in three non-orthogonal-polarization states, merely with a single-size nanostructure design approach. Specifically, nanostructured metasurfaces acting as nano-polarizer arrays can modulate the incident light intensity pixel-by-pixel by controlling the orientation angles of nanostructures, governed by Malus's law. Hence, by inserting a metasurface between a bulk-optic polarizer and an analyzer, and elaborately controlling their polarization combinations, we show that the Malus-assisted metasurface can simultaneously record a continuous gray-image and two independent binary-patterns in three different information channels. We experimentally demonstrate this concept by recording three independent gray-images right at the metasurface surface. With the advantages of high information density, high security, high compatibility and ultracompactness, the proposed gray-imaging meta-device can play a significant role in the field of optical storage, anti-counterfeiting, and information multiplexing, etc.
RESUMO
Metasurfaces have shown unusual abilities to modulate the phase, amplitude and polarization of an incident lightwave with spatial resolution at the subwavelength scale. Here, we experimentally demonstrate a dielectric metasurface enabled with both geometric phase and magnetic resonance that scatters an incident light beam filling the full reflective 2π-space with high-uniformity. Specifically, by delicately reconfiguring the orientations of dielectric nanobricks acting as nano-half-waveplates in a metasurface, the optical power of phase-modulated output light is almost equally allocated to all diffraction orders filling the full reflection space. The measured beam non-uniformity in the full hemispheric space, defined as the relative standard deviation (RSD) of all scattered optical power, is only around 0.25. More interestingly, since the target intensity distribution in a uniform design is rotationally centrosymmetric, the diffraction results are identical under arbitrary polarization states, e.g., circularly polarized, linearly polarized or even unpolarized light, which brings great convenience in practical applications. The proposed uniform-backscattering metasurface enjoys the advantages including polarization insensitivity, high-integration-density and high-stability, which has great potential in sensing, lighting, laser ranging, free-space optical communication and so on.
RESUMO
BACKGROUND: Upper respiratory tract infections (URTIs) is a common disease in children, which is also known as the common cold. Pediatric Tuina is a common treatment that Traditional Chinese Medicine (TCM) doctors commonly use for URTIs. However, there has no relevant systematic review studied on its effects and safety been reported. We plan to perform a systematically reviewing of all the clinical evidence on the effectiveness and safety of Tuina for URTIs in children. METHODS: We will conduct the literature searching in the following electronic databases: Pubmed, Embase, Cochrane Library, Web of science, Chinese National Knowledge Infrastructure (CNKI), VIP, Wanfang, China Biomedical Literature Database (CBM), Chinese Clinical Trial Registry System. The time limit for retrieving studies is from establishment to July 2019 for each database. All published randomized controlled trials (RTCs) related to this review will be included. Review Manager (V.5.3.5) will be implemented for the assessment of bias risk and data analyses. Subgroup analysis and sensitivity analysis will be performed based on the conditions of included data. RESULTS: A high-quality synthesis of current evidence of Tuina for children with URTIs will be provided in this study. CONCLUSION: This systematic review will provide evidence of whether Tuina is an effective intervention for children with URTIs. PROSPERO REGISTRATION NUMBER: CRD42019126963.