One-way Surface Research Articles

Preparation and characterization of Baijiu Jiuzao cellulose nanofibers-kafirin composite bio-film with excellent physical properties

Jiuzao is the main solid by-products of Baijiu industry, which contain a high amount of underutilized cellulose and proteins. In recent years, cellulose nanofibers mixed with proteins to prepare biodegradable bio-based film materials have received widespread attention. In this study, we propose a novel method to simultaneously extract kafirin and cellulose from strong-flavor type of Jiuzao, and modify cellulose to prepare cellulose nanofibers by the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxide) oxidation-pressure homogenization technique, and finally mix kafirin with cellulose nanofibers to prepare a new biodegradable bio-based composite film. Based on the analysis of one-way and response surface experiments, the highest purity of cellulose was 82.04 %. During cellulose oxidation, when NaClO was added at 25 mmol/g, cellulose nanofibers have a particle size of 80–120 nm, a crystallinity of 65.8°. Finally, kafirin and cellulose nanofibers were mixed to prepare films. The results showed that when cellulose nanofibers were added at 1 %, the film surface was smooth, the light transmittance was 60.8 %, and the tensile strength was 9.17 MPa at maximum, which was 104 % higher than pure protein film. The contact angle was 34.3°. This paper provides new ideas and theoretical basis for preparing biodegradable bio-based composite film materials, and improves the added value of Jiuzao.

Wideband isolator based on one-way surface magnetoplasmons with ultra-high isolation

In this paper, we present a new type of isolator based on one-way surface magnetoplasmons (SMPs) at microwave frequencies, and it is the first time that an experimental prototype of isolator with wideband and ultra-high isolation is realized using SMP waveguide. The proposed model with gyromagnetic and dielectric layers is systematically analyzed to obtain the dispersion properties of all the possible modes, and a one-way SMP mode is found to have the unidirectional transmission property. In simulation and experiment with metallic waveguide loaded with yttrium–iron–garnet (YIG) ferrite, the scattering parameters and the field distributions agree well with the analysis and verify the one-way transmission property. The isolation is found to be as high as 80 dB and the typical value of insertion loss is 1 dB. Besides, the one-way transmission band can be controlled by changing the magnetic bias. From theoretical analysis and simulation, it is found that with a tiny value of 10 Oe of the magnetic bias, the relative bandwidth can be tuned to be greater than 50%. Compared with conventional isolators, this one-way SMP isolator has the advantages of ultra-high isolation, wide relative frequency band, and requires much smaller bias field, which has promising potential in non-reciprocal applications.

Optimization of Extraction Process and Analysis of Biological Activity of Flavonoids from Leaves of Cultivated 'Qi-Nan' Agarwood.

Currently, the planting of 'Qi-Nan' is continuously increasing, yet a substantial amount of 'Qi-Nan' leaves have not been properly exploited. To improve the 'Qi-Nan' tree 's utilization value, 'Qi-Nan' leaves were used as a raw material. An ultrasound-assisted method was performed to obtain the flavonoids from the 'Qi-Nan' leaves, followed by optimization of the extraction factors using a one-way and response surface methodology to enhance the extraction of flavonoids. Subsequently, the composition of the flavonoids, as well as their bioactive abilities, were analyzed by ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) and in vitro activity testing methods. The findings demonstrated that a 1:50 material-to-liquid ratio, 60% ethanol concentration, and ultrasound-assisted extraction time of 30 min were the ideal procedures for extracting flavonoids (flavonoid content: 6.68%). Meanwhile, the 'Qi-Nan' leaves possessed the antioxidant and medicinal potential to prevent diabetes and Alzheimer 's disease, as evidenced by the semi-inhibitory concentrations (IC50 values) of flavonoid extracts for scavenging DPPH• free radicals, scavenging ABTS•+ free radicals, inhibiting acetylcholinesterase, and inhibiting α-glucosidase, which were 12.64 μg/mL, 66.58 μg/mL, 102.31 μg/mL, and 38.76 μg/mL, respectively, which indicated that the 'Qi-Nan' leaves possessed the properties of antioxidant and medicinal potential for the prevention of Alzheimer 's disease and diabetes.

Enhanced Magneto-Optical Effect in Heterostructures Composed of Epsilon-Near-Zero Materials and Truncated Photonic Crystals

Optical non-reciprocal transmission plays an important role in many applications such as optical isolation, switching, and integrated photonic circuits. However, the non-reciprocity of natural magneto-optical (MO) materials is too weak to be widely used in the actual applications. Magnetized metamaterials enable the exploration of a new regime about the MO effect, including the enhanced non-reciprocal transmission and one-way surface waves. In this work, the Fano-type interference effect is studied in the heterostructure composed of a magnetized epsilon-near-zero material and a truncated photonic crystal. The inherent weak MO activity is significantly enhanced in the heterostructure because of the field intensity enhancement mechanism and Fano interference. The results provide a way to design novel optical non-reciprocal devices with excellent performance using metamaterials.

Chiral and multiple one-way surface states on photonic gyroelectric metamaterials with small Chern number.

Topological one-way surface states allow light to pass through sharp corners without reflection. In order to enhance the capability of surface routing devices, multiple one-way surface modes are usually required. Different from previously reported multiple surface modes achieved with large Chern number photonic media, we realize multiple surface waves on a continuous medium with small Chern number, i.e., |C| = 1. The new topological phase is found when the hyperbolic and double semi-ellipsoid-like cone bands are simultaneously gapped by vacuum state. We also find the degeneracy of multiple one-way surface waves in the double semi-ellipsoid-like metamaterials. The propagation direction of the waves is determined by their own ellipticities. Our results may help to construct surface state devices with multiplexing capability and higher coupling efficiency.

Robust Acoustic Pulling Using Chiral Surface Waves

We show that long-range and robust acoustic pulling can be achieved by using a pair of one-way chiral surface waves supported on the interface between two phononic crystals composed of spinning cylinders with equal but opposite spinning velocities embedded in water. When the chiral surface mode with a relative small Bloch wave vector is excited, the particle located in the interface waveguide will scatter the excited surface mode to another chiral surface mode with a greater Bloch wave vector, resulting in an acoustic pulling force, irrespective of the size and material of the particle. Thanks to the backscattering immunity of the chiral surface waves against local disorders, the particle can be pulled following a flexible trajectory as determined by the shape of the interface. As such, this new acoustic pulling scheme overcomes some of the limitations of the traditional acoustic pulling using structured beams, such as short pulling distances, straight-line type pulling and strong dependence on the scattering properties of the particle. Our work may also inspire the application of topological acoustics to acoustic manipulations.

Tuning the chiral edge states and unidirectional transmission by surface morphology of gyromagnetic photonic crystal

Though topologically protected one-way edge states are determined by the bulk mode of the magnetic photonic crystal (MPC), the edge profile can influence topological edge states and associated wave propagation since the waves at the states are localized at the edge of the photonic crystal. By truncating the honeycomb structured MPC at the same side but at different cuts, we show the MPC slab will present different topological edge band, and the associate transmission of a one-way surface wave will change a lot. We demonstrate the good transmission efficiency of the one-way surface wave needs a good field localization at the edge of MPC at the topological edge states, and bearded edge has better field localization ability than the zigzag one in a wider frequency range. In addition to the different cuts, one can modify the topological edge state by tuning the radius of outmost rods of the slab or the material parameters of the rods, which does not affect the topological state of the MPC. Our study provides an effective means to improve the performances of the devices based on topological edge states of the materials, such as one-way waveguide.

Unidirectional and robust propagating surface magnetoplasmon in magneto-optical coaxial waveguides

In this paper, a novel coaxial waveguide comprising a hollow cylinder made of a magneto-optical material and a metal wire at the axis is proposed. The surface magnetoplasmon and guided modes of the waveguide are studied. The results show that the dispersion relation and electromagnetic field distribution are highly sensitive to the operating frequency and physical dimensions of the structure. It is demonstrated that there exist three different types of modes, that is bulk mode, surface mode, and regular mode. By adjusting the operating frequency and reducing the inner diameter of the hollow cylinder, the regular mode is suppressed and only the surface mode remains, which shows one-way propagating property. Moreover, the one-way surface mode is robust against backscattering at defect and surface roughness, which has good potential in practice. The unique properties of this waveguide are demonstrated through mode analyzes as well as numerical simulations.

Ultra-subwavelength focusing and giant magnetic-field enhancement in a low-loss one-way waveguide based on remanence

The subwavelength focusing based on surface plasmon polaritons has been widely explored in tapered metallic structures. However, the efficiency of energy localization is relatively weak, largely due to high propagation loss and strong back reflection. Here, we propose a three-dimensional (3D) straight-tapered one-way surface magnetoplasmon (SMP) waveguide with the end surface of ∼10−4λ0 × 10−4λ0 to achieve energy focusing in the microwave regime. Due to low propagation loss of SMP, we achieve huge magnetic field enhancement in such an ultra-subwavelength area, by five orders of magnitude. Instead of using an external static magnetic field, our proposed SMP waveguide relies on remanence, which is very convenient for operating practical 3D applications. These results show promising applications in magnetic-field enhancing or quenching fluorescence, luminescence or nonlinearity of two-dimensional materials, novel scanning near-field microwave microscopy and energy storage.

Do truly unidirectional surface plasmon-polaritons exist?

In this work, we revisit the topic of surface waves on nonreciprocal plasmonic structures, and clarify whether strictly unidirectional surface plasmon-polaritons are allowed to exist in this material platform. By investigating different three-dimensional configurations and frequency regimes, we theoretically show that, while conventional surface magneto-plasmons are not strictly unidirectional due to nonlocal effects, consistent with recent predictions made in the literature, another important class of one-way surface plasmon-polaritons, existing at an interface with an opaque isotropic material, robustly preserves their unidirectionality even in the presence of nonlocality, and for arbitrarily small levels of dissipation. We also investigate the extreme behavior of terminated unidirectional waveguiding structures, for both classes of surface waves, and discuss their counterintuitive implications.

All-optical logic gates based on unidirectional surface plasmon polaritons

Optical logic gates are important elements in optical computing and optical circuits. In this study, all-optical logic gates, including OR, XOR, XNOR, NAND, and NOT gates, are obtained in a composite structure composed of gyroelectric material and metal based on the interference and absorption of surface waves. In the composite structure, a Y-shaped channel through which surface plasmon polaritons propagate unidirectionally is formed. Through the ingenious one-way surface plasmon polaritons, backscattering and side-scattering generated by the composite structure and influencing the surrounding devices are prohibited effectively. The precisely controlled optical phase difference ensures the realization of five different logic gates with high contrast ratios. The maximum contrast ratios for XOR, XNOR, NAND, and NOT gates are 31.64dB, 43.47dB, 31.47dB, and 43.47dB, respectively. The output logic states "1"or "0" obtained by different logic inputs have nearly the same light intensity. Our research results provide the possibility for constructing all-optical integrated logic devices.

Topologically protected broadband rerouting of propagating waves around complex objects

Abstract Achieving robust propagation and guiding of electromagnetic waves through complex and disordered structures is a major goal of modern photonics research, for both classical and quantum applications. Although the realization of backscattering-free and disorder-immune guided waves has recently become possible through various photonic schemes inspired by topological insulators in condensed matter physics, the interaction between such topologically protected guided waves and free-space propagating waves remains mostly unexplored, especially in the context of scattering systems. Here, we theoretically demonstrate that free-space propagating plane waves can be efficiently coupled into topological one-way surface waves, which can seamlessly flow around sharp corners and electrically large barriers and release their energy back into free space in the form of leaky-wave radiation. We exploit this physical mechanism to realize topologically protected wave-rerouting around an electrically large impenetrable object of complex shape, with transmission efficiency exceeding 90%, over a relatively broad bandwidth. The proposed topological wave-rerouting scheme is based on a stratified structure composed of a topologically nontrivial magnetized plasmonic material coated by a suitable isotropic layer. Our results may open a new avenue in the field of topological photonics and electromagnetics, for applications that require engineered interactions between guided waves and free-space propagating waves, including for complex beam-routing systems and advanced stealth technology. More generally, our work may pave the way for robust defect/damage-immune scattering and radiating systems.

Reflectionless magnetic-to-optical differential modulator based on gyroelectric material

In this work, we present a theoretical scheme to create a reflectionless magnetic-to-optical differential modulator constructed with two mirror symmetrical star structures of three interfaces formed of two gyroelectric materials and a bulk of metal. Taking advantage of two star structures, we receive the modulated signal through coherent superposition of two one-way surface waves. The modulator we have designed can realize the modulation of surface wave in response to magnetic signal. Reflected waves affecting the surrounding devices are prohibited. In addition, the modulator is mini-sized with simple construction and can detect the magnetic signal in an integrated optical system.

One-Way Electromagnetic Mode Guided by the Mechanism of Total Internal Reflection

One-way electromagnetic mode that is guided by the mechanism of total internal reflection (TIR) can be realized in terahertz regime. In the optical system consisting of a dielectric layer sandwiched between magnetized semiconductor and metal, the one-way TIR mode can be immune to backscattering at imperfections. This mode possesses a broad band when high-order TIR modes are suppressed in the relevant semiconductor bandgap. Furthermore, it is shown that compared with one-way surface magnetoplasmons, the one-way TIR mode can more effectively match with the fundamental mode of conventional optical waveguide.

Possibilities of applying motif group parameters for description roughness of turned surfaces

This article explores the methodology of assessing the applicability of roughness parameters from the motif group to the evaluation of one-way and periodic geometrical surface structures. The results of surface roughness measurements of aluminum samples turned with variable kinematic parameters were presented. Usability of using surface motifs in combination with selected parameters described in ISO standards for assessment of geometrical structures characteristic for longitudinal turning was shown.

The effects of three-dimensional defects on one-way surface plasmon propagation for photonic topological insulators comprised of continuum media.

We have investigated one-way surface plasmon-polaritons (SPPs) at the interface of a continuum magnetoplasma material and metal, in the presence of three-dimensional surface defects. Bulk electromagnetic modes of continuum materials have Chern numbers, analogous to those of photonic crystals. This can lead to the appearance of topologically-protected surface modes at material interfaces, propagating at frequencies inside the bandgap of the bulk materials. Previous studies considered two-dimensional structures; here we consider the effect of three-dimensional defects, and show that, although backward propagation/reflection cannot occur, side scattering does take place and has significant effect on the propagation of the surface mode. Several different waveguiding geometries are considered for reducing the effects of side-scattering, and we also consider the effects of metal loss.

One-way helical electromagnetic wave propagation supported by magnetized plasma

In this paper we reveal the presence of photonic one-way helical surface states in a simple natural system- magnetized plasma. The application of an external magnetic field to a bulk plasma body not only breaks time-reversal-symmetry but also leads to separation of Equi-Frequency Contour surfaces (EFCs) to form topologically nontrivial gaps in k space. Interestingly, these EFCs support topologically protected surface states. We numerically investigate an interface between magnetized plasma, using a realistic model for parameter dispersion, and vacuum, to confirm the existence of one-way scatter-immune helical surface states. Unlike previous proposals for achieving photonic one-way propagation, our scheme does not require the use of artificial structures and should therefore be simple to implement experimentally.

One-way surface magnetoplasmon cavity and its application for nonreciprocal devices.

We theoretically analyze surface magnetoplasmon modes in a compact circular cavity made of magneto-optical material under a static magnetic field. Such a cavity provides two different methods for the surface wave to circulate in a unidirectional manner around the cavity, which offers more freedom, both in the one-way direction and in the frequency range, for designing nonreciprocal photonic components. We also show the interaction between this one-way cavity and waveguides through the example of a circulator, which lays the fundamental groundwork for potential nonreciprocal devices.

Robust estimates of soil moisture and latent heat flux coupling strength obtained from triple collocation

Land surface models (LSMs) are often applied to predict the one-way coupling strength between surface soil moisture (SM) and latent heat (LH) flux. However, the ability of LSMs to accurately represent such coupling has not been adequately established. Likewise, the estimation of SM/LH coupling strength using ground-based observational data is potentially compromised by the impact of independent SM and LH measurements errors. Here we apply a new statistical technique to acquire estimates of one-way SM/LH coupling strength which are nonbiased in the presence of random error using a triple collocation approach based on leveraging the simultaneous availability of independent SM and LH estimates acquired from (1) LSMs, (2) satellite remote sensing, and (3) ground-based observations. Results suggest that LSMs do not generally overestimate the strength of one-way surface SM/LH coupling.

One-way surface states due to nonreciprocal light-line crossing

We revisit the problem of the surface plasmon polariton (SPP) propagation at a metal–magneto-optical dielectric interface and predict a conceptually different regime of one-way surface wave propagation. We show that in the presence of magnetization, the nonreciprocal crossing of the light-line by dispersion curve of SPPs is possible. This leads to the formation of leaky-wave surface states in one of the propagation directions, whereas in other direction SPPs are confined to the interface. We show that such a regime of surface plasmon propagation is fundamentally different from one-way regimes of surface waves predicted earlier.