Achromatic Metalens over 60 nm Bandwidth in the Visible and Metalens with Reverse Chromatic Dispersion.

In this Letter, we experimentally report an achromatic metalens (AML) operating over a continuous bandwidth in the visible. This is accomplished via dispersion engineering of dielectric phase shifters: titanium dioxide nanopillars tiled on a dielectric spacer layer above a metallic mirror. The AML works in reflection mode with a focal length independent of wavelength from λ = 490 to 550 nm. We also design a metalens with reverse chromatic dispersion, where the focal length increases as the wavelength increases, contrary to conventional diffractive lenses. The ability to engineer the chromatic dispersion of metalenses at will enables a wide variety of applications that were not previously possible. In particular, for the AML design, we envision applications such as imaging under LED illumination, fluorescence, and photoluminescence spectroscopy.

Polarization-Insensitive Metalenses at Visible Wavelengths.

In this Letter, we demonstrate highly efficient, polarization-insensitive planar lenses (metalenses) at red, green, and blue wavelengths (λ = 660, 532, and 405 nm). Metalenses with numerical apertures (NA) of 0.85 and 0.6 and corresponding efficiencies as high as 60% and 90% are achieved. These metalenses are less than 600 nm-thick and can focus incident light down to diffraction-limited spots as small as ∼0.64λ and provide high-resolution imaging. In addition, the focal spots are very symmetric with high Strehl ratios. The single step lithography and compatibility with large-scale fabrication processes make metalenses highly promising for widespread applications in imaging and spectroscopy.

Multispectral Chiral Imaging with a Metalens.

The vast majority of biologically active compounds, ranging from amino acids to essential nutrients such as glucose, possess intrinsic handedness. This in turn gives rise to chiral optical properties that provide a basis for detecting and quantifying enantio-specific concentrations of these molecules. However, traditional chiroptical spectroscopy and imaging techniques require cascading of multiple optical components in sophisticated setups. Here, we present a planar lens with an engineered dispersive response, which simultaneously forms two images with opposite helicity of an object within the same field-of-view. In this way, chiroptical properties can be probed across the visible spectrum using only the lens and a camera without the addition of polarizers or dispersive optical devices. We map the circular dichroism of the exoskeleton of a chiral beetle, Chrysina gloriosa, which is known to exhibit high reflectivity of left-circularly polarized light, with high spatial resolution limited by the numerical aperture of the planar lens. Our results demonstrate the potential of metasurfaces in realizing a compact and multifunctional device with unprecedented imaging capabilities.

Development of microsatellite markers for Mytilus coruscus (Mytilidae), an economically important mussel in the East China Sea.

Twelve new polymorphic microsatellite loci were developed for the hard-shelled mussel, Mytilus coruscus. In 32 individuals from a wild population of coastal Zhoushan, Zhejiang Province, China, the number of alleles at these loci varied from 3 to 15, with a mean of 5.667. The mean observed and expected heterozygosities were 0.6927 and 0.6591, respectively. Among these polymorphic microsatellite loci, three (MC42, MC129, and MC180) significantly deviated from Hardy-Weinberg equilibrium after sequential Bonferroni's correction. All other microsatellite loci were in linkage equilibrium. These microsatellite loci will be useful for detecting genetic differences and for planning aquaculture management of M. coruscus.

Isolation and characterization of new polymorphic microsatellite markers from the cuttlefish Sepiella maindroni (Cephalopoda; Sepiidae).

Fifteen new polymorphic microsatellite loci were developed for the cuttlefish Sepiella maindroni. In 32 individuals from a wild population of coastal Ningde, Fujian Province, China, the number of alleles at these loci varied between 2 and 12, with an average of 5.86. The mean observed and expected heterozygosities were 0.6917 and 0.5993, respectively. Among these polymorphic microsatellite loci, 4 (SM2, SM19, SM40, and SM81) significantly deviated from Hardy-Weinberg equilibrium after sequential Bonferroni's correction. All of them were in linkage equilibrium. These microsatellite loci would be useful for evaluating the effect of releasing on extant S. maindroni populations as well as for investigating genetic diversity and population structure of this species.