title: Transformation-optical design of adaptive beam bends and beam expanders.
abstract: We describe the design of adaptive beam bends and beam splitters with arbitrary bend and split angles by use of finite embedded coordinate transformations. The devices do not exhibit reflection at the entrance or exit surfaces. It is shown that moderate and practically achievable values of the relative permittivity and permeability can be obtained for beam bends and splitters with both small and large bend radius. The devices are also discussed in the context of reconfigurable metamaterials, in which the bend and split angles can be dynamically tuned. The performance of adaptive beam bends and splitters is demonstrated in full wave simulations based on a finite-element method. Furthermore, the design of an adaptively adjustable transformation-optical beam expander/compressor is presented. It is observed that a pure transformation-optical design cannot result in a reflectionless beam expander/compressor.
authors.affiliation: Department of Electrical and Computer Engineering, Center for Metamaterials and Integrated Plasmonics, Duke University, Durham, NC 27708, USA. marco.rahm@duke.edu
authors.forename: M
authors.initials: M
authors.lastname: Rahm
authors.forename: D A
authors.initials: DA
authors.lastname: Roberts
authors.forename: J B
authors.initials: JB
authors.lastname: Pendry
authors.forename: D R
authors.initials: DR
authors.lastname: Smith
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D008027:Light; D008420:Manufactured Materials; D008962:Models, Theoretical; D055095:Optics and Photonics / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation