Differentiated design strategies toward broadband achromatic and polarizationinsensitive metalenses

Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffractive nature plagues them when used in many practical applications.Current solutions for eliminating chromatic aberration usually rely on searching through many meta-atoms to seek designs that satisfy both phase and phase dispersion preconditions,inevitably leading to intensive design efforts.Moreover,most schemes are commonly valid for incidence with a specific spin state.Here,inspired by the Rayleigh criterion for spot resolution,we present a design principle for broadband achromatic and polarization-insensitive metalenses using two sets of anisotropic nanofins based on phase change material Ge2Sb2Se4Te1.By limiting the rotation angles of all nanofins to either 0 deg or 90 deg,the metalens with a suitable numerical aperture constructed by this fashion allows for achromatic and polarization-insensitive performance across the wavelength range of 4–5μm,while maintaining high focusing efficiency and diffraction-limited performance.We also demonstrate the versatility of our approach by successfully implementing the generation of broadband achromatic and polarization-insensitive focusing optical vortex.This work represents a major advance in achromatic metalenses and may find more applications in compact and chip-scale devices.

All-fiber-based ultrastable laser with long-term frequency stability of 1.1×10^(-14)

We demonstrate an ultrastable miniaturized transportable laser system at 1550 nm by locking it to an optical fiber delay line[FDL].To achieve optimized long-term frequency stability,the FDL was placed into a vacuum chamber with a five-layer thermal shield,and a delicate two-stage active temperature stabilization,an optical power stabilization,and an RF power stabilization were applied in the system.A fractional frequency stability of better than 3.2×10^[-15]at 1 s averaging time and1.1×10^[-14]at 1000 s averaging time was achieved,which is the best long-term frequency stability of an all-fiber-based ultrastable laser observed to date.

All-fiber-based photonic microwave generation with 10^(-15) frequency instability

We demonstrate an all-fiber-based photonic microwave generation with 10^(-15) frequency instability.The system consists of an ultra-stable laser by optical fiber delay line,an all-fiber-based"figure-of-nine"optical frequency comb,a high signal-tonoise ratio photonic detection unit,and a microwave frequency synthesizer.The whole optical links are made from optical fiber and optical fiber components,which renders the whole system compactness,reliability,and robustness with respect to environmental influences.Frequency instabilities of 3.5×10^(-15) at 100 s for 6.834 GHz signal and 4.3×10^(-15) at 100 s for9.192 GHz signal were achieved.

All-fiber-based laser with 200 mHz linewidth

We demonstrate the frequency stabilization of a 1.55 μm erbium-doped fiber laser by locking it to a 5-km-long optical fiber delay line(FDL).The stabilized laser is characterized via comparison with a second identical laser system.We obtain a fractional frequency stability of better than 3 × 10^-15 over time scales of 1–10 s and a laser linewidth of 0.2 Hz, which is the narrowest linewidth of an FDL-stabilized laser observed to date.

Facile fabrication of superior antibacterial cotton fabric based on ZnO nanoparticles/quaternary ammonium salts hybrid composites and mechanism study

In the research for the safe and efficiently antibacterial cotton fabrics to minimize risk for human health,an organic–inorganic hybrid material of ZnO nanoparticles(NPs)and quaternary ammonium salt(QAS)was employed to modify cotton fabrics by a dipping–padding–drying method.The synergistic effects of ZnO NPs and QAS on the structure and antibacterial properties of cotton fabrics were studied in detail.Results displayed that the QAS and ZnO NPs were immobilized firmly in cotton fabric by the formation of chemical covalent bonds and silica gel structure.ZnO/QAS/cotton had a good inhibitory effect on the growth of E.coli and S.aureus,with superior antibacterial efficiency of>99.99%.ZnO/QAS/cotton preserved good mechanical property,water absorbability,and limpness.We also provided a detailed analysis of antibacterial mechanism for the hybrid materials.The contact mechanism and the Zn2+release were considered as the main mechanisms for the ZnO/QAS/cotton,while the reactive oxygen species(ROS)generation only had a little contribution to the antibacterial activity.In short,the excellent integrated properties endowed the hybrid cotton fabrics as potential application in many fields,like healthcare,food packaging.

Vibration-insensitive fiber spool for laser stabilization

Excess frequency noise induced by mechanical vibration is the dominant noise source at low Fourier frequencies in fiber-delay-line stabilized lasers. To resolve this problem, a double-winding fiber spool is designed and implemented that has ultralow acceleration sensitivity in all spatial directions. By carefully choosing the optimal geometry parameters of the fiber spool, we achieve acceleration sensitivity of 8 × 10^-11/g and 3 × 10^-11/g(g denotes the gravitational acceleration) in axial and radial directions, respectively.

Arachis species:High-quality forage crops—nutritional properties and breeding strategies to expand their utilization and feeding value

Plants of the genus Arachis originated from South America and are cultivated worldwide.The genus Arachis contains 83 species and nine intrageneric taxonomic sections.The cultivated peanut(Arachis hypogaea L.)belongs to the Arachis section,the forage peanut(Arachis pintoi Krapov.&W.C.Greg.)belongs to the Caulorrhizae section,and the perennial peanut(Arachis glabrata Benth.)belongs to the Rhizomatosae section.These three peanut species have been developed for use as fodder crops.This review summarizes the forage value of Arachis species.Forage and perennial peanuts can be intercropped with forage species to feed livestock.The cultivated peanut vines and peanut by-products,such as peanut skins and peanut meal,are also high-quality fodder used to feed sheep,cattle,and poultry.A major limiting factor in terms of adopting forage and perennial peanuts as forage crops is their limited resistance to frosts,resulting from their low winter hardiness.Therefore,the feeding value of cultivated peanuts is higher compared to forage and perennial peanuts.This review suggests that Arachis is a suitable forage crop,focusing on their nutritional properties and breeding to increase their performance under cultivation and feeding value.