Phys.org March 11, 2024 Metasurfaces are candidates for vectorial optics polarization, but their static post-fabrication geometry largely limits dynamic tunability. Liquid crystal (LC) is usually employed as an additional index-changing layer together with metasurfaces. However, most of the reported LCs only impart a varying but uniform phase on top of that from the metasurface. An international team of researchers (China, Singapore) pixelated a single-layer LC to display versatile and tunable vectorial holography, in which the polarization and amplitude could be arbitrarily and independently controlled at varying spatial positions. The subtle and vectorial LC-holography highlighted the broadband and electrically switchable functionalities. […]
Tag Archives: Polarization
Nanosheet technology developed to boost energy storage dielectric capacitors
Science Daily July 4, 2023 Dielectric capacitors can become ideal, safe energy storage devices. However, they yield rather low energy densities compared with other energy storage devices such as batteries and supercapacitors. Researchers in Japan designed ultrahigh energy storage capacitors using two-dimensional (2D) high-κ dielectric perovskites (Ca2Nam–3NbmO3m+1; m = 3–6). Individual Ca2Nam–3NbmO3m+1 nanosheets exhibited an ultrahigh dielectric strength even in the monolayer form, which exceeded those of conventional dielectric materials. Multilayer stacked nanosheet capacitors exhibited ultrahigh energy densities, high efficiencies (>90%), excellent reliability (>107 cycles), and temperature stability (−50–300 °C); the maximum energy density was much higher than those of […]
Controlling light with a material three atoms thick
Phys.org October 22, 2021 An international team of researchers (USA – Caltech, Japan) constructed a material from black phosphorous which has anisotropic optical properties. As the black phosphorous is a semiconductor, structures built from black phosphorous can control the polarization of light as an electric signal is applied to them. This makes it possible to make an array of these elements each of which can convert the polarization into a different reflected polarization state. A telecommunications device based on thin layers of black phosphorous could tune the polarization of each signal so that they don’t interfere with each other. This […]
The world’s thinnest technology—only two atoms thick
Phys.org June 30, 2021 An international team of researchers (Israel, Japan) reports a stable ferroelectric order emerging at the interface between two naturally grown flakes of hexagonal boron nitride, which were stacked together in a metastable non-centrosymmetric parallel orientation. They observed alternating domains of inverted normal polarization, caused by a lateral shift of one lattice site between the domains. Reversible polarization switching coupled to lateral sliding was achieved by scanning a biased tip above the surface. Their calculations trace the origin of the phenomenon to a subtle interplay between charge redistribution and ionic displacement and provide intuitive insights to explore […]
Metasurface opens world of polarization
Science Daily June 3, 2020 To achieve broad polarization manipulation, multiple birefringent materials need to be stacked one top of another making these devices bulky and inefficient. Researchers at Harvard University used topological optimization to design birefringent materials. They started with the functionality of the metasurface and allowed the algorithm to explore the huge parameter space to develop a pattern that can best deliver that function. The resulting metasurface was composed of nested half circles. The odd shapes have opened a whole new world of birefringence. They can achieve broad polarization manipulations; polarization can be tuned by changing the angle […]