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Chirality refers to the structural property of an object that cannot be superposed onto its mirror image. The existence of chirality in nature is universal, ranging from molecules at the nanoscale to gastropod shells at the macroscale. Light can be chiral as well. Circularly polarized light with opposite helicity has its electric field vector rotating clockwise or counterclockwise during propagation. Chiral light-matter interactions are widely used in molecule detection, optical communication and quantum information processing. In this talk, I will discuss how to engineer the chiral light-matter interaction based on metamaterials and nano photonic structures towards novel imaging and sensing applications. I will first present a new concept of chiral metamirrors, which can achieve near-perfect reflection of designated circularly polarized light without reversing its handedness, yet complete absorption of the other polarization state [1]. Such a metamaterial can be used for polarimetric imaging to extract the polarization information of light [2]. Recently, we have applied the deep learning approach to accelerate the design of chiral metamaterials with prescribed chiroptical responses [3]. Finally, I will discuss the generation of chiral hotspots in silicon nanocube dimers that can amplify circular dichroism signals by one order of magnitude [4]. Our findings would lead to integrated devices for circular dichroism spectroscopy, enantioselective sensing, sorting and synthesis.
References: [1] Z. J. Wang et al., "Circular Dichroism Metamirrors with Near-Perfect Extinction", ACS Photonics 3, 2096 (2016); [2] L. Kang et al., "Preserving Spin States upon Reflection: Linear and Nonlinear Responses of a Chiral Meta-Mirror", Nano Letters 17, 7102 (2017); [3] W. Ma et al., "Deep-Learning-Enabled On-Demand Design of Chiral Metamaterials", ACS Nano 12, 6326 (2018). Research Highlight in Nature Photonics 12, 443 (2018); [4] K. Yao and Y. M. Liu, "Enhancing circular dichroism by chiral hotspots in silicon nanocube dimers", Nanocale 10, 8779 (2018).
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