The nanoscale structures inspired by the natural catenaries can achromatically spin light wave.

Optical metasurfaces with high quality factors (Q-factors) of chiral resonances can boost substantially light-matter interaction for various applications of chiral response in ultrathin, active, and nonlinear metadevices. However, current approaches lack the flexibility to enhance and tune the chirality and Q-factor simultaneously. Here, we suggest a design of chiral metasurface supporting bound state in the continuum (BIC) and demonstrate experimentally chiroptical responses with ultra-high Q-factors and near-perfect circular dichroism (CD = 0.93) at optical frequencies. We employ the symmetry-reduced meta-atoms with high birefringence supporting winding elliptical eigenstate polarizations with opposite helicity. It provides a convenient way for achieving the maximal planar chirality tuned by either breaking in-plane structure symmetry or changing illumination angle. Beyond linear CD, we also achieved strong near-field enhancement CD and near-unitary nonlinear CD in the same planar chiral metasurface design with circular eigen-polarization. Sharply resonant chirality realized in planar metasurfaces promises various practical applications including chiral lasers and chiral nonlinear filters.

The advance of nanophotonics has provided a variety of avenues for light–matter interaction at the nanometer scale through the enriched mechanisms for physical and chemical reactions induced by nanometer-confined optical probes in nanocomposite materials. These emerging nanophotonic devices and materials have enabled researchers to develop disruptive methods of tremendously increasing the storage capacity of current optical memory. In this paper, we present a review of the recent advancements in nanophotonics-enabled optical storage techniques. Particularly, we offer our perspective of using them as optical storage arrays for next-generation exabyte data centers.

A twist on optical multiplexing: Information can be encoded using various properties of light. Optical multiplexing frequency, brightness, and polarization have played crucial roles in information technologies, high-capacity data storage, high-speed communications, and biological sensing. Angular momentum is another degree of freedom that could increase capacity further. Typically, however, the bulk optical elements used to determine the angular momentum of light limit possible on-chip processing. Ren et al. take a nanophotonics approach to measure and sort light co-propagating with different states of angular momentum (see the Perspective by Molina-Terriza). The approach is promising for on-chip multiplex processing of optical signals. Science , this issue p. 805 ; see also p. 774