Causality and passivity constraints appear in constitutive equations of any material or meta-material and characterise the interaction electromagnetic radiation with matter. These constraints result in the well-known physical limitations which affect the design of a cloak. However, there are items in the realm of partial differential equations, namely transmission eigenvalue problems in electromagnetics, which have ignored such physical limitations and are nonetheless believed to play a role in cloaking theory. Herewith, some properties of elliptic partial differential equations are recalled; the main properties of Maxwell-Herglotz pairs are listed; transmission eigenvalue problems are stated, their connections with the properties of the “far-field scattering” operator and to “nearly non-scattering” solutions are discussed. Finally, results coming from transmission eigenvalue problems of electromagnetics, where material models ignore causality and passivity, are shown to be of limited application to cloaking.
Giovanni Franco Crosta, "Metamaterials for cloaking: the implications of causality," Proc. SPIE 10671, Metamaterials XI, 106710I (Presented at SPIE Photonics Europe: April 24, 2018; Published: 7 May 2018); https://doi.org/10.1117/12.2305346.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations.