Planar optics constructed from subwavelength artificial atoms have been suggested as a route to the physical realization of steganography with controlled intrinsic redundancy at single-pixel levels. Unfortunately, two-dimensional geometries with uniform flat profiles offer limited structural redundancy and make it difficult to create advanced crypto-information in multiplexed physical divisions. Here, we reveal that splashing three-dimensional (3D) plasmonic nanovolcanoes could allow for a steganographic strategy in angular anisotropy, with high resolution, full coloration, and transient control of structural profiles. Highly reproducible 3D morphologies of volcanic nanosplashes are demonstrated by creating a standardized recipe of laser parameters. Such single nanovolcanoes can be well controlled individually at different splashing stages and thus provide a lithography-free fashion to access various spectral responses of angularly coordinated transverse and vertical modes, leading to the full-range coloration. This chip-scale demonstration of steganographic color images in angular anisotropy unfolds a long-ignored scheme for structured metasurfaces and thereby provides a paradigm for information security and anticounterfeiting.

In this letter, a detecting method for the magneto-optical constant is presented by using weak measurements. The photonic spin Hall effect (PSHE), which manifests itself as spin-dependent splitting, is introduced to characterize the magneto-optical constant, and a propagation model to describe the quantitative relation between the magneto-optical constant and the PSHE is established. According to the amplified shift of the PSHE detected by weak measurements, we determinate the magneto-optical constant of the Fe film sample. The Kerr rotation is measured via the standard polarimetry method to verify the rationality and feasibility of our method. These findings may provide possible applications in magnetic physics research.

The chiral structures have displayed some inevitable and fascinating properties in many research fields, such as chemistry, biology, mathematics, and physics. In this Article, we report the use of stepwise glancing angle deposition technology to produce the 3D chiral nanostructures. Through the optimization of deposition parameters (such as the orientation angle of poly styrene spheres (PSs) array, the deposition angle, thickness, and number), a great number of chiral structures have been achieved, and their size depends on the diameter of PS spheres. These chiral structures all can be simulated and predesigned through the use of a 3D geometrical model, which greatly improves the efficiency of this method. In addition, the circular dichroism spectrum shows that these chiral structures own an obvious Cotton effect, indicating their potential application as 3D chiral metamaterials.

In this Letter, we report a phenomenon of large in-plane-photonic-spin-splitting (IPPSS) in the case of a linear polarized Gaussian light beam reflected from an air-glass interface at the Brewster angle. The IPPSS-induced displacement reaches ∼12.4  μm, which is quite larger than the previously reported value. Particularly, the IPPSS is extremely sensitive (∼70  μm/deg) to the incident polarization. We also find that the direction of the spin accumulation can be switched by adjusting the incident polarization slightly. These findings may have useful applications in spin manipulation and precise polarization metrology.

A smart-hydrogel-based ultrasensitive grating system with ultra-low detection limit for highly-selective and rapid detection of trace heavy metal ions is developed.

Micro‐Raman imaging and spectroscopy has become an established technique for the characterization of biogenic hydroxyapatite as, for example, the primary constituent of human teeth. However, few studies have yet gone beyond a qualitative analysis of the Raman response providing only limited insight into spatial heterogeneity of composition, structure, and degree of crystallinity. Here, we show how correlative electron microprobe and extended hyperspectral Raman imaging with high spatial and spectral resolution, with peak position and linewidth analysis, and from the μm to mm scale, provides insight into structural characteristics in dentin and enamel. From comparison of healthy and hypoplastic teeth as a representative tooth disease example, we determine variations in degree of crystallinity, both locally across the dentin–enamel junction, and with distinct long‐range spatial variations. We identify a correlation of spectral peak position and linewidth as a measure of crystal lattice disorder across tubules, dentin, dentin–enamel junction, and enamel. This correlative Raman imaging and analysis approach may help to provide a better understanding of apatite geochemistry and biomineralization.

A simple grating system based on poly­(N-isopropylacrylamide-co-acrylamide) (poly­(NIPAM-co-AAm)) hydrogel for sensitive and rapid detection of ethanol concentration is developed. The hydrogel gratings enable ethanol-induced shrinking, thus changing their refractive index and height. The changes in the optical property and structure of hydrogel gratings allow efficient conversion and amplification of signals of ethanol concentration into changes in the diffraction efficiency for facile detection of ethanol concentration via a simple optical detection system. By adjusting the molar ratios of NIPAM and AAm in the hydrogel gratings, significant diffraction efficiency changes in response to ethanol concentrations in the range of 0–30 vol % at different temperatures can be achieved for sensitive ethanol detection. Moreover, the hydrogel gratings with nanometer-sized height and uniform surface relief structures allow rapid response time (less than 2 min) and good repeatability for ethanol detection.

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