Generalized laws of reflection and refraction from transformation optics

Based on transformation optics, we introduce another set of generalized laws of reflection and refraction (differs from that of [Science 334, 333 (2011)]), through which a transformation media slab is derived as a meta-surface, producing anomalous reflection and refraction for all polarizations of incident light.Comment: 7 pages, 3 figure

Design issues in data warehousing : a case study

Data warehousing is the foundation of DSS (decision support system), of which the goal is to enable decision makers to make better business decisions based on analysis of historic data related to the business operation. Data warehousing has become a major business trend, both for product and service sectors and for application to daily business in all industries. In this thesis, we compare and discuss the two data models and two methods of OLAP (MOLAP and ROLAP). The two data models and two OLAPs are not mutually exclusive in any project. An example of the hybrid design is presented in a case study. In this project, we are able to apply two data models at different stages of the data warehouse. By combining ER model, Star Schema and aggregate table in one architecture, we are able to maximize on both storage capacity and query performance. In addition to the selection of data models, the choice between MOLAP and ROLAP is discussed. When the objectives of the client are clearly defined, the functional requirements of the data warehouse are determined, and the amount of data is relatively small, MOLAP would likely be a better choice because of its superior performance and intuitive querying mechanism. ROLAP becomes a more suitable candidate for OLAP when the amount of data is exceedingly large, and the client does not want to leave out anything. Again, it is possible, even desirable, for both OLAP methods to be applied in one project to compliment each other

Collimating lenses from non-Euclidean transformation optics

Based on the non-Euclidean transformation optics, we design a thin metamaterial lens that can achieve wide-beam radiation by embedding a simple source (a point source in three-dimensional case or a line current source in two-dimensional case). The scheme is performed on a layer-by-layer geometry to convert curved surfaces in virtual space to flat sheets, which pile up and form the entire lens in physical space. Compared to previous designs, the lens has no extreme material parameters. Simulation results confirm its functionality.Comment: 12 pages, 6 figure

Manipulating Smith-Purcell Emission with Babinet Metasurfaces

Swift electrons moving closely parallel to a periodic grating produce far-field radiation of light, which is known as the Smith-Purcell effect. In this letter, we demonstrate that designer Babinet metasurfaces composed of C-aperture resonators offer a powerful control over the polarization state of the Smith-Purcell emission, which can hardly be achieved via traditional gratings. By coupling the intrinsically nonradiative energy bound at the source current sheet to the out-of-plane electric dipole and in-plane magnetic dipole of the C-aperture resonator, we are able to excite cross-polarized light thanks to the bianisotropic nature of the metasurface. The polarization direction of the emitted light is aligned with the orientation of the C-aperture resonator. Furthermore, the efficiency of the Smith-Purcell emission from Babinet metasurfaces is significantly increased by 84%, in comparison with the case of conventional gratings. These findings not only open up a new way to manipulate the electron-beam-induced emission in the near-field region but also promise compact, tunable, and efficient light sources and particle detectors.United States. Office of Naval Research (N00014-16-1-2049