title: Gain-assisted transformation optics.
abstract: Loss severely degrades the cloaking effect of the device designed by traditional transformation. In this letter, we propose gain-assisted transformation optics to overcome the loss problem by introducing gain media into a spherical cloak. The gain media, which can amplify the electromagnetic fields, is controlled precisely to compensate the inherent loss in experimental realization of cloaks. We discuss the significance of controlling embedded gain materials in the context of the inverse design mechanism, which allows us to wisely select realizable materials with constant gain and loss along the radius. For practical realizations, isotropic spherical gain-assisted cloak is designed. Full-wave simulations validate the proposed design concept, which can be utilized to alleviate the inevitable loss problem in transformational optical devices.
authors.affiliation: EHF Key Laboratory of Fundamental Science, School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
authors.forename: Tiancheng
authors.initials: T
authors.lastname: Han
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Qiu
authors.forename: Jiaming
authors.initials: J
authors.lastname: Hao
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Tang
authors.forename: Said
authors.initials: S
authors.lastname: Zouhdi
mesh_terms: D000669:Amplifiers, Electronic; D004867:Equipment Design; D019544:Equipment Failure Analysis; D055096:Optical Devices