De Leon Israel, Horton Matthew J, Schulz Sebastian A, Upham Jeremy, Banzer Peter, Boyd Robert W
Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton, Ottawa, ON, K1N 6N5, Canada.
Institute of Optics and Department of Physics and Astronomy, University of Rochester, Rochester NY, 14627.
Sci Rep. 2015 Sep 4;5:13034. doi: 10.1038/srep13034.
Metamaterials and metasurfaces provide a paradigm-changing approach for manipulating light. Their potential has been evinced by recent demonstrations of chiral responses much greater than those of natural materials. Here, we demonstrate theoretically and experimentally that the extrinsic chiral response of a metasurface can be dramatically enhanced by near-field diffraction effects. At the core of this phenomenon are lattice plasmon modes that respond selectively to the illumination's polarization handedness. The metasurface exhibits sharp features in its circular dichroism spectra, which are tunable over a broad bandwidth by changing the illumination angle over a few degrees. Using this property, we demonstrate an ultra-thin circular-polarization sensitive spectral filter with a linewidth of ~10 nm, which can be dynamically tuned over a spectral range of 200 nm. Chiral diffractive metasurfaces, such as the one proposed here, open exciting possibilities for ultra-thin photonic devices with tunable, spin-controlled functionality.
超材料和超表面为操控光提供了一种改变范式的方法。近期关于手性响应远大于天然材料的手性响应的演示证明了它们的潜力。在此，我们通过理论和实验证明，超表面的外在手性响应可通过近场衍射效应得到显著增强。该现象的核心是晶格等离子体激元模式，其对光照的偏振手性有选择性响应。超表面在其圆二色光谱中呈现出尖锐特征，通过在几度范围内改变光照角度，可在很宽的带宽内对其进行调谐。利用这一特性，我们展示了一种线宽约为10纳米的超薄圆偏振敏感光谱滤波器，它可在200纳米光谱范围内动态调谐。诸如本文所提出的手性衍射超表面，为具有可调谐、自旋控制功能的超薄光子器件开启了令人兴奋的可能性。
