‡State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, China.
§Department of Electromagnetic Engineering, School of Electrical Engineering, Royal Institute of Technology, S-100 44 Stockholm, Sweden.
ACS Nano. 2015 Apr 28;9(4):4111-9. doi: 10.1021/acsnano.5b00218. Epub 2015 Apr 13.
We design, fabricate, and experimentally demonstrate an ultrathin, broadband half-wave plate in the near-infrared range using a plasmonic metasurface. The simulated results show that the linear polarization conversion efficiency is over 97% with over 90% reflectance across an 800 nm bandwidth. Moreover, simulated and experimental results indicate that such broadband and high-efficiency performance is also sustained over a wide range of incident angles. To further obtain a background-free half-wave plate, we arrange such a plate as a periodic array of integrated supercells made of several plasmonic antennas with high linear polarization conversion efficiency, consequently achieving a reflection-phase gradient for the cross-polarized beam. In this design, the anomalous (cross-polarized) and the normal (copolarized) reflected beams become spatially separated, hence enabling highly efficient and robust, background-free polarization conversion along with broadband operation. Our results provide strategies for creating compact, integrated, and high-performance plasmonic circuits and devices.
我们设计、制作并实验验证了一种基于等离子体超表面的近红外宽带半波片。模拟结果表明，在 800nm 带宽内，线性偏振转换效率超过 97%，反射率超过 90%。此外，模拟和实验结果表明，这种宽带和高效性能在宽入射角范围内也能保持。为了进一步获得无背景的半波片，我们将这种超表面排列成由几个具有高线性偏振转换效率的等离子体天线组成的集成超元的周期性阵列，从而为交叉偏振光实现反射相梯度。在这种设计中，反常（交叉偏振）和正常（同偏振）反射光束在空间上分离，从而能够实现高效、稳健、无背景的偏振转换以及宽带操作。我们的研究结果为创建紧凑、集成和高性能的等离子体电路和器件提供了策略。
