Full-parameter omnidirectional transformation optical devices

Yuan Gao; Yu Luo; Jingjing Zhang; Zhengjie Huang; Bin Zheng; Hongsheng Chen; Dexin Ye

doi:10.1093/nsr/nwad171

Full-parameter omnidirectional transformation optical devices

Natl Sci Rev. 2023 Jun 8;11(3):nwad171. doi: 10.1093/nsr/nwad171. eCollection 2024 Mar.

Authors

Yuan Gao¹, Yu Luo^{2

3}, Jingjing Zhang^{4

5}, Zhengjie Huang¹, Bin Zheng^{1

6

7

8}, Hongsheng Chen^{1

6

7

8}, Dexin Ye¹

Affiliations

¹ Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310027, China.
² School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.
³ CNRS-International-NTU-Thales Research Alliance, Nanyang Technological University, Singapore 637553, Singapore.
⁴ Institute of Electromagnetic Space, Southeast University, Nanjing 210096, China.
⁵ State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China.
⁶ International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining 314400, China.
⁷ Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua 321099, China.
⁸ Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing 312000, China.

Abstract

Transformation optics (TO) provides an unprecedented technique to control electromagnetic (EM) waves by engineering the constitutive parameters of the surrounding medium through a proper spatial transformation. In general, ideal transformation optical devices require simultaneous electric and magnetic responses along all three dimensions. To ease the practical implementation, previous studies usually made use of reduced parameters or other simplified approaches, which inevitably introduce extra reflection or unwanted phase shift. Up to today, experimental realizations of full-parameter transformation optical devices in free space are still quite limited. Here, a general design strategy is proposed to solve this problem. As a specific example, a full-parameter spatial-compression TO medium with constitutive parameters taking the diagonal form diag(a, a, 1/a) for the TM wave incidence was designed and realized experimentally. Such spatial-compression TO media were then applied to the implementation of an ideal omnidirectional invisibility cloak capable of concealing a large-scale object over a wide range of illumination angles. Both the simulation and experiment confirm that the cloak allows for nearly unity transmission of EM waves in the forward direction without introducing extra scattering or phase shift. This work constitutes an important stepping stone for future practical implementation of arbitrary full-parameter omnidirectional transformation optical devices.

Keywords: full-parameter invisibility cloak; omnidirectional impedance matching; transformation optical devices.