Scattering exceptional point in the visible

Abstract

Exceptional point (EP) is a special degeneracy of non-Hermitian systems. One-dimensional transmission systems operating at EPs are widely studied and applied to chiral conversion and sensing. Lately, two-dimensional systems at EPs have been exploited for their exotic scattering features, yet so far been limited to only the non-visible waveband. Here, we report a universal paradigm for achieving a high-efficiency EP in the visible by leveraging interlayer loss to accurately control the interplay between the lossy structure and scattering lightwaves. A bilayer framework is demonstrated to reflect back the incident light from the left side ( | r−1 | >0.999) and absorb the incident light from the right side ( | r+1 | < 10–4). As a proof of concept, a bilayer metasurface is demonstrated to reflect and absorb the incident light with experimental efficiencies of 88% and 85%, respectively, at 532 nm. Our results open the way for a new class of nanoscale devices and power up new opportunities for EP physics.

Exceptional dynamics at exceptional points

“…Recently, in a newly published paper in Light: Science & Applications 8 , Xinbin Cheng from MOE Key Laboratory of Advanced Micro-Structured Materials, Tongji University, Shanghai, and Cheng-Wei Qiu from the National University of Singapore, Singapore, have jointly demonstrated such EP in the visible spectrum based on a bilayered metasurface, as illustrated in Fig. 1 .…”

Enhanced Circular Dichroism for Achiral Sensing Based on a DNA-Origami-Empowered Anapole Metasurface

“…During the past decade, metasurfaces, a class of artificial nanophotonic structures with orderly design, − have been proposed for enhanced chiral sensing by increasing the chiral light-matter interaction. The key to enhancing chiral sensing, which is the magnitude of CD signals, is to squeeze the electromagnetic field into the subwavelength region and generate enhanced optical chirality. − In the early stage, plasmonic metasurfaces , were introduced to amplify the inherently weak CD signals and shift them into the visible/near-infrared range, but the photothermal heating effects stemming from intrinsic optical loss are unavoidable.…”