Publications by authors named "Kuang Zhang"

33 Publications

Short-circuited stub-loaded spoof surface plasmon polariton transmission lines with flexibly controllable lower out-of-band rejections.

Opt Lett 2021 Sep;46(17):4354-4357

This Letter proposes an approach to develop a spoof surface plasmon polariton (SSPP) transmission line (TL) by loading short-circuited (SC) shunt stubs. Lower out-of-band rejections can be flexibly controlled without affecting the upper cutoff frequency by independently modifying the stubs. Dispersion analysis of the SSPP unit is realized by theoretical calculation and circuit simulation to predict the upper cutoff frequency of the proposed SSPP TL simultaneously. Also, parametric sweeping of the SC shunt stubs is performed based on circuit simulation to investigate their impacts on the lower and upper out-of-band rejections of the proposed SSPP TL. In addition, electric field distributions of different types of TLs are simulated and compared to study the transmission characteristics of the proposed SSPP TL. The lower cutoff frequency can be flexibly tuned in a wide range, from 1.2 to 2.1 GHz, in the simulations. The measured 3-dB fractional bandwidth is about 128.1%, covering a range from 1.19 to 5.43 GHz. The numerical and experimental results are compatible, which verifies the feasibility of the proposed approach. This approach can offer more convenience and flexibility for controlling the rejections of the SSPP by introducing up to four tuning parameters. More importantly, the proposed SSPP TL avoids using the substrate integrated waveguide (SIW) technique, which shows the potential to decrease the transverse width (0.44), especially at lower frequencies (e.g., 1.2 GHz), and to reduce the complexity in designing the high-efficiency transition. This work paves the way for the development of novel SSPP-based microwave devices.
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http://dx.doi.org/10.1364/OL.435842DOI Listing
September 2021

Multi-band terahertz resonant absorption based on an all-dielectric grating metasurface for chlorpyrifos sensing.

Opt Express 2021 Apr;29(9):13563-13575

Perfect metasurface absorbers play a significant role in imaging, detecting, and manipulating terahertz radiation. We utilize all-dielectric gratings to demonstrate tunable multi-band absorption in the terahertz region. Simulation reveals quad-band and tri-band absorption from 0.2 to 2.5 THz for different grating depths. Coupled-mode theory can explain the absorption phenomenon. The absorption amplitude can be precisely controlled by changing the pump beam fluence. Furthermore, the resonant frequency is sensitive to the medium's refractive index, suggesting the absorber may be of great potential in the sensor detection field. The experimental results exhibit a high detectivity of pesticides.
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http://dx.doi.org/10.1364/OE.423256DOI Listing
April 2021

Polarization-multiplexed Huygens metasurface holography.

Opt Lett 2020 Oct;45(19):5488-5491

Huygens metasurface, as a subcategory of metamaterials, shows great potential in the capacity and efficiency of electromagnetic wave manipulation within a subwavelength scale. Here, the transmission-type Huygens metasurface is demonstrated for complete and independent control of orthogonally polarized transmitted waves by constructing pairs of crossed electric and magnetic resonances in three-sheet meta-atoms as the building blocks for holographic imaging. Under incoherent horizontally and vertically polarized illuminations, two designated holographic images with negligible mutual interferences are accomplished with at least 62.95% measured imaging efficiency and 63.53 signal-to-noise ratio, respectively. This work addresses several major issues in traditional polarization-multiplexed holography with regard to transmission-coefficient manipulation capacity, image fidelity, and simple fabrication technique, empowering advanced research and applications in polarization-selective microwave devices and information processing.
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http://dx.doi.org/10.1364/OL.403060DOI Listing
October 2020

A Fully Phase-Modulated Metasurface as An Energy-Controllable Circular Polarization Router.

Adv Sci (Weinh) 2020 Sep 16;7(18):2001437. Epub 2020 Jul 16.

Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore.

Geometric metasurfaces primarily follow the physical mechanism of Pancharatnam-Berry (PB) phases, empowering wavefront control of cross-polarized reflective/transmissive light components. However, inherently accompanying the cross-polarized components, the copolarized output components have not been attempted in parallel in existing works. Here, a general method is proposed to construct phase-modulated metasurfaces for implementing functionalities separately in co- and cross-polarized output fields under circularly polarized (CP) incidence, which is impossible to achieve with solely a geometric phase. By introducing a propagation phase as an additional degree of freedom, the electromagnetic (EM) energy carried by co- and cross-polarized transmitted fields can be fully phase-modulated with independent wavefronts. Under one CP incidence, a metasurface for separate functionalities with controllable energy repartition is verified by simulations and proof-of-principle microwave experiments. A variety of applications can be readily expected in spin-selective optics, spin-Hall metasurfaces, and multitasked metasurfaces operating in both reflective and transmissive modes.
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http://dx.doi.org/10.1002/advs.202001437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7509705PMC
September 2020

Independent phase modulation for quadruplex polarization channels enabled by chirality-assisted geometric-phase metasurfaces.

Nat Commun 2020 08 21;11(1):4186. Epub 2020 Aug 21.

Université Côte d'Azur, CNRS, Centre de Recherche sur l'Hétéro-Epitaxie et ses Applications (CRHEA), 06560, Valbonne, France.

Geometric-phase metasurfaces, recently utilized for controlling wavefronts of circular polarized (CP) electromagnetic waves, are drastically limited to the cross-polarization modality. Combining geometric with propagation phase allows to further control the co-polarized output channel, nevertheless addressing only similar functionality on both co-polarized outputs for the two different CP incident beams. Here we introduce the concept of chirality-assisted phase as a degree of freedom, which could decouple the two co-polarized outputs, and thus be an alternative solution for designing arbitrary modulated-phase metasurfaces with distinct wavefront manipulation in all four CP output channels. Two metasurfaces are demonstrated with four arbitrary refraction wavefronts, and orbital angular momentum modes with four independent topological charge, showcasing complete and independent manipulation of all possible CP channels in transmission. This additional phase addressing mechanism will lead to new components, ranging from broadband achromatic devices to the multiplexing of wavefronts for application in reconfigurable-beam antenna and wireless communication systems.
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http://dx.doi.org/10.1038/s41467-020-17773-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7442839PMC
August 2020

Helicity-switched hologram utilizing a polarization-free multi-bit coding metasurface.

Opt Express 2020 Jul;28(15):22669-22678

In this work, a polarization-free coding metasurface is proposed to manipulate circularly polarized waves. Compared to a Pancharatnam-Berry phase metasurface, the proposed design not only allows for overcoming anti-symmetrical response characteristics between orthogonal circularly polarized states to enable achieving identical functionality under both right-handed and left-handed circularly polarized wave illuminations and avoiding polarization-conversion losses but also offers additional degree of freedom in the control of handedness. As a proof-of-concept demonstration, a polarization-free multi-bit coding metasurface is designed to realize helicity-switched holograms in the microwave region. Experimental measurements performed on a fabricated prototype reveal outstanding imaging quality with extremely high imaging efficiency above 76% for arbitrary polarizations at 10 GHz. Our proposed method expands the route in manipulating circularly polarized waves and can be applied over the whole electromagnetic spectrum for wavefront manipulation.
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http://dx.doi.org/10.1364/OE.400274DOI Listing
July 2020

High-density linkage map construction and QTL analyses for fiber quality, yield and morphological traits using CottonSNP63K array in upland cotton (Gossypium hirsutum L.).

BMC Genomics 2019 Nov 21;20(1):889. Epub 2019 Nov 21.

Cotton Incorporated, 6399 Weston Parkway, Cary, NC, 27513, USA.

Background: Improving fiber quality and yield are the primary research objectives in cotton breeding for enhancing the economic viability and sustainability of Upland cotton production. Identifying the quantitative trait loci (QTL) for fiber quality and yield traits using the high-density SNP-based genetic maps allows for bridging genomics with cotton breeding through marker assisted and genomic selection. In this study, a recombinant inbred line (RIL) population, derived from cross between two parental accessions, which represent broad allele diversity in Upland cotton, was used to construct high-density SNP-based linkage maps and to map the QTLs controlling important cotton traits.

Results: Molecular genetic mapping using RIL population produced a genetic map of 3129 SNPs, mapped at a density of 1.41 cM. Genetic maps of the individual chromosomes showed good collinearity with the sequence based physical map. A total of 106 QTLs were identified which included 59 QTLs for six fiber quality traits, 38 QTLs for four yield traits and 9 QTLs for two morphological traits. Sub-genome wide, 57 QTLs were mapped in A sub-genome and 49 were mapped in D sub-genome. More than 75% of the QTLs with favorable alleles were contributed by the parental accession NC05AZ06. Forty-six mapped QTLs each explained more than 10% of the phenotypic variation. Further, we identified 21 QTL clusters where 12 QTL clusters were mapped in the A sub-genome and 9 were mapped in the D sub-genome. Candidate gene analyses of the 11 stable QTL harboring genomic regions identified 19 putative genes which had functional role in cotton fiber development.

Conclusion: We constructed a high-density genetic map of SNPs in Upland cotton. Collinearity between genetic and physical maps indicated no major structural changes in the genetic mapping populations. Most traits showed high broad-sense heritability. One hundred and six QTLs were identified for the fiber quality, yield and morphological traits. Majority of the QTLs with favorable alleles were contributed by improved parental accession. More than 70% of the mapped QTLs shared the similar map position with previously reported QTLs which suggest the genetic relatedness of Upland cotton germplasm. Identification of QTL clusters could explain the correlation among some fiber quality traits in cotton. Stable and major QTLs and QTL clusters of traits identified in the current study could be the targets for map-based cloning and marker assisted selection (MAS) in cotton breeding. The genomic region on D12 containing the major stable QTLs for micronaire, fiber strength and lint percentage could be potential targets for MAS and gene cloning of fiber quality traits in cotton.
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http://dx.doi.org/10.1186/s12864-019-6214-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6878679PMC
November 2019

High-Efficiency Metalenses with Switchable Functionalities in Microwave Region.

ACS Appl Mater Interfaces 2019 Aug 25;11(31):28423-28430. Epub 2019 Jul 25.

Department of Microwave Engineering , Harbin Institute of Technology , Harbin 150001 , China.

Regarding miniaturized and integrated systems, a single flat device that possesses diversified functionalities is highly desirable in optical to microwave regimes. With this perspective, bifunctional metalenses constructed by meta-atoms with integrated response to propagation phase and geometric phase are proposed for independent manipulation of right-handed and left-handed circularly polarized waves. The derived general criterion is verified in the microwave region from three bifunctional metalenses operating in transmission manner. The proof-of-concept measurements show that all these metalenses exhibit two independent functionalities that can be switched by flipping the helicity of the incident illumination. Very high efficiencies of around 80%, with peak value of 91%, are achieved by the ultrathin metasurfaces of thickness 0.15λ. The proposed metasurfaces provide a promising route for the realization of reconfigurable lenses and antennas in wireless communication systems.
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http://dx.doi.org/10.1021/acsami.9b07102DOI Listing
August 2019

Carbon Molecular Sieve Membrane Preparation by Economical Coating and Pyrolysis of Porous Polymer Hollow Fibers.

Angew Chem Int Ed Engl 2019 Aug 25;58(35):12149-12153. Epub 2019 Jul 25.

School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Dr. NW, Atlanta, GA, 30332, USA.

Dip coating and pyrolysis processes are used to create multi-layer asymmetric carbon molecular sieve (CMS) hollow fiber membranes with excellent gas separation properties. Coating of an economical engineered support with a high-performance polyimide to create precursor fibers with a dense skin layer reduces material cost by 25-fold compared to monolithic precursors or ceramic supports. CMS permeation results with CO /CH (50:50) mixed gas feed show attractive CO /CH selectivity of 58.8 and CO permeance of 310 GPU at 35 °C.
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http://dx.doi.org/10.1002/anie.201906653DOI Listing
August 2019

Multi-focus hologram utilizing Pancharatnam-Berry phase elements based metamirror.

Opt Lett 2019 May;44(9):2189-2192

An ultrathin reflection-type metamirror is proposed for multi-focusing with any desired focusing fashion including focal number and location. The metamirror is composed of reflection-type Pancharatnam-Berry (P-B) phase elements, which are able to provide full reflection phase of 2π, together with near-unity reflection efficiency by judiciously engineering the rotation angle of each latter element. A holographic algorithm is utilized to calculate the phase distribution at the interface of the metamirror to achieve the desired multi-focus spots. Experimental demonstrations performed in microwave region show good imaging quality with high reflection efficiency and imaging efficiency. The proposed metamirror provides a high-performance solution for low-cost and lightweight beam-shaping and beam-focusing devices.
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http://dx.doi.org/10.1364/OL.44.002189DOI Listing
May 2019

Coding Huygens' metasurface for enhanced quality holographic imaging.

Opt Express 2019 Mar;27(5):7108-7119

In this paper, coding Huygens' metasurface (CHM) is proposed for holographic imaging with enhanced quality. A weighted holographic algorithm is used to calculate the phase distribution at the interface and to design the CHM. Experimental demonstration performed in the microwave region validates holographic imaging with the ability to modulate energy distribution among focal points and improve image quality. By judiciously engineering both electric and magnetic dipolar resonators, the proposed digital Huygens' meta-atom is able to provide a full transmission-phase covering the whole range of 2π together with a near-unity transmission efficiency. The proof-of-concept experiments show that holographic imaging quality can be indeed improved by using digital meta-atoms with several bits. Furthermore, the modulation of intensity distribution among focal points is experimentally realized by using the 3-bits CHM. The proposed CHM hologram shows great potential in a variety of application fields, such as programmable high-resolution imaging lenses, microscopy, data storage, information processing, and computer-generated holograms.
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http://dx.doi.org/10.1364/OE.27.007108DOI Listing
March 2019

Publisher Correction: Mixed matrix formulations with MOF molecular sieving for key energy-intensive separations.

Nat Mater 2019 01;18(1):90

School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA.

In the version of this Article originally published, the units of the y axis of Fig. 3b were incorrectly given as '10 cm s'; they should have been '10 cm s'. This has been corrected in the online versions of the Article.
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http://dx.doi.org/10.1038/s41563-018-0253-8DOI Listing
January 2019

Anisakid and raphidascaridid nematodes (Ascaridoidea) infection in the important marine food-fish Lophius litulon (Jordan) (Lophiiformes: Lophiidae).

Int J Food Microbiol 2018 Nov 3;284:105-111. Epub 2018 Aug 3.

Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Science, Hebei Normal University, 050024 Shijiazhuang, Hebei Province, PR China. Electronic address:

The yellow goosefish Lophius litulon is a commercially important marine fish species. However, our present knowledge of the occurrence of nematode parasites in L. litulon remains incomplete. A total of 42 L. litulon collected from the East China Sea were investigated for the presence of ascaridoid nematodes. Eight ascaridoid species with different developmental stages were identified using morphological and molecular methods, including Anisakis pegreffii (L3s), Raphidascaris lophii (L3s), Hysterothylacium fabri (L3s, L4s), H. aduncum (L3s, L4s, Ads), H. amoyense (L3s), H. liparis (L3s, L4s), H. zhoushanense (L3s) and H. sinense (L4s, Ads). The overall prevalence of infection was 100% (mean intensity 18.6). Of them, H. fabri (L3s, L4s), H. liparis (L3s, L4s), H. sinense (L4s, Ads), H. amoyense (L3s) and H. zhoushanense (L3s) were reported from this fish for the first time. Anisakis pegreffii (L3s) with prevalence 83.3% and mean intensity 12.1, represents the predominant species. The genus Hysterothylacium with six species detected herein, has the highest richness of species diversity. Our present results provided important information for determining the composition of the nematode parasite fauna of L. litulon in the East China Sea, and it is also a key step for the risk assessment of human anisakidosis when L. litulon caught from the East China Sea are consumed.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2018.08.002DOI Listing
November 2018

Broadband high-order mode of spoof surface plasmon polaritons supported by compact complementary structure with high efficiency.

Opt Lett 2018 Jul;43(13):3176-3179

In this work, spoof surface plasmon polaritons (SSPPs) supported by microstrip lines with T-shaped complementary grooves are proposed. Compared with the traditional SSPP structure based on single-conductor transmission lines, a broadband high-order mode of SSPPs can be predicted from the dispersion diagrams. Besides, a decrease in transverse size of 75% can be realized under the same asymptotic frequency. Then, a smooth and simple transition, which is composed of gradient complementary grooves, is designed to realize high-efficiency excitation and support practical applications of the high-order mode of SSPPs. As a result, a seamless connection with microstrip lines is easily achieved without using flaring ground, which simplifies the design procedure. Based on the proposed structure, a prototype of a SSPP waveguide is designed and fabricated. Both numerical and experimental results validate efficient excitation and broadband propagation (up to 12 GHz) of the high-order mode of SSPPs. This work will greatly accelerate the development of advanced plasmonic integrated circuits at microwave frequencies.
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http://dx.doi.org/10.1364/OL.43.003176DOI Listing
July 2018

Topological Data Analysis as a Morphometric Method: Using Persistent Homology to Demarcate a Leaf Morphospace.

Front Plant Sci 2018 25;9:553. Epub 2018 Apr 25.

Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States.

Current morphometric methods that comprehensively measure shape cannot compare the disparate leaf shapes found in seed plants and are sensitive to processing artifacts. We explore the use of persistent homology, a topological method applied as a filtration across simplicial complexes (or more simply, a method to measure topological features of spaces across different spatial resolutions), to overcome these limitations. The described method isolates subsets of shape features and measures the spatial relationship of neighboring pixel densities in a shape. We apply the method to the analysis of 182,707 leaves, both published and unpublished, representing 141 plant families collected from 75 sites throughout the world. By measuring leaves from throughout the seed plants using persistent homology, a defined morphospace comparing all leaves is demarcated. Clear differences in shape between major phylogenetic groups are detected and estimates of leaf shape diversity within plant families are made. The approach predicts plant family above chance. The application of a persistent homology method, using topological features, to measure leaf shape allows for a unified morphometric framework to measure plant form, including shapes, textures, patterns, and branching architectures.
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http://dx.doi.org/10.3389/fpls.2018.00553DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5996898PMC
April 2018

Gradient phase partially reflecting surfaces for beam steering in microwave antennas.

Opt Express 2018 Mar;26(6):6724-6738

A metal-dielectric-metal gradient phase partially reflecting surface based on the combination of a gradient index dielectric substrate with an inductive and a capacitive grids, is designed at microwave frequencies for antenna applications. The gradient index is obtained by realizing air holes of different dimensions in a dielectric host material. A prototype of the gradient index dielectric substrate is fabricated through three-dimensional printing, an additive fabrication technology. It is then associated to two patterned metallic grids to realize a partially reflecting surface with a gradient phase behavior. For experimental validation, the partially reflective surface is used as reflector in a low-profile Fabry-Perot cavity antenna. An angular enhancement of the emitted beam in a desired direction is reported by further engineering the phase introduced by the inductive and the capacitive grids. Far-field measurements are performed on fabricated antenna prototypes to validate the concept. Such gradient phase reflective surface paves the way to low-cost easy-made microwave metal-dielectric surfaces incorporating functionalities such as beam control, forming and collimation.
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http://dx.doi.org/10.1364/OE.26.006724DOI Listing
March 2018

Experimental validation of active holographic metasurface for electrically beam steering.

Opt Express 2018 Mar;26(5):6316-6324

In this paper, a holographic metasurface possessing beam scanning capability at fixed frequency is presented. The desired radiation beam is obtained by using a reference wave to excite a sinusoidally-modulated impedance surface, which is equivalent to the interference pattern between the radiation wave and reference wave. By changing the bias voltage of varactor diodes loaded on the sub-wavelength unit cells, the variation range of the modulated impedance can be tuned, resulting in the change of radiation angle. Both the simulation and experimental results demonstrate that the direction of the radiation beam can be tuned in the range from 23° to 50° at 5.5 GHz. The proposed holographic metasurface shows great potential applications in constructing planar beam scanning antenna for integrated microwave system.
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http://dx.doi.org/10.1364/OE.26.006316DOI Listing
March 2018

High-efficiency surface plasmonic polariton waveguides with enhanced low-frequency performance in microwave frequencies.

Opt Express 2017 Feb;25(3):2121-2129

In this paper, a planar waveguide based on spoof surface plasmon polaritons (SSPPs) with metals on both sides of the corrugated strip as grounds is firstly proposed in microwave region. Simple and efficient conversion between guided waves and SSPPs is realized by gradient corrugated strip with grounds on both sides. Compared with plasmonic waveguide with flaring ground [Laser Photonics Rev. 8, 146 (2014)], the addition of grounds suppresses the radiation loss effectively and improves the low-frequency performance with tighter field confinement, which leads to a wider operating bandwidth. Moreover, as the asymptotic frequency of SSPPs decreasing, the confinement of SSPPs is further enhanced by a defected ground structure (DGS), which is achieved by the periodic grooves symmetrical to those on the corrugated strip. Therefore, miniaturization of the proposed waveguide can be realized. Measured results validate both high efficiency of momentum and impedance matching and enhanced performance in the region of lower frequencies with the wave vectors close to those in free space. Such results have significant values in plasmonic functional devices and integrated circuits in microwave frequencies.
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http://dx.doi.org/10.1364/OE.25.002121DOI Listing
February 2017

Mixed matrix formulations with MOF molecular sieving for key energy-intensive separations.

Nat Mater 2018 03 12;17(3):283-289. Epub 2018 Feb 12.

School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA.

Membrane-based separations can improve energy efficiency and reduce the environmental impacts associated with traditional approaches. Nevertheless, many challenges must be overcome to design membranes that can replace conventional gas separation processes. Here, we report on the incorporation of engineered submicrometre-sized metal-organic framework (MOF) crystals into polymers to form hybrid materials that successfully translate the excellent molecular sieving properties of face-centred cubic (fcu)-MOFs into the resultant membranes. We demonstrate, simultaneously, exceptionally enhanced separation performance in hybrid membranes for two challenging and economically important applications: the removal of CO and HS from natural gas and the separation of butane isomers. Notably, the membrane molecular sieving properties demonstrate that the deliberately regulated and contracted MOF pore-aperture size can discriminate between molecular pairs. The improved performance results from precise control of the linkers delimiting the triangular window, which is the sole entrance to the fcu-MOF pore. This rational-design hybrid approach provides a general toolbox for enhancing the transport properties of advanced membranes bearing molecular sieve fillers with sub-nanometre-sized pore-apertures.
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http://dx.doi.org/10.1038/s41563-017-0013-1DOI Listing
March 2018

Phase-engineered metalenses to generate converging and non-diffractive vortex beam carrying orbital angular momentum in microwave region.

Opt Express 2018 Jan;26(2):1351-1360

In this paper, ultra-thin metalenses are proposed to generate converging and non-diffractive vortex beam carrying orbital angular momentum (OAM) in microwave region. Phase changes are introduced to the transmission cross-polarized wave by tailoring spatial orientation of Pancharatnam-Berry phase unit cell. Based on the superposition of phase profile of spiral phase plate and that of a converging lens or an axicon, vortex beam carrying OAM mode generated by the metalens can also exhibit characteristics of a focusing beam or a Bessel beam. Measured field intensities and phase distributions at microwave frequencies verify the theoretical design procedure. The proposed method provides an efficient approach to control the radius of vortex beam carrying OAM mode in microwave wireless applications for medium-short range distance.
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http://dx.doi.org/10.1364/OE.26.001351DOI Listing
January 2018

Morphological and molecular characterization of Seuratascaris numidica (Seurat, 1917) (Ascaridida: Ascarididae).

Acta Parasitol 2018 Mar;63(1):154-159

Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, 050024 Shijiazhuang, Hebei Province, P. R. China.

Seuratascaris numidica (Seurat, 1917) is a specialized nematode species parasitizing amphibians only. In the present study, the detailed morphology of this poorly known species was studied using light and scanning electron microscopy based on the newly material collected from Hoplobatrachus chinensis (Osbeck) (Amphibia: Anura) in China. We found that the relative length of intestinal caecum in our male specimens (representing 68.4-71.1% of oesophageal length) is slighter longer than the previously reported data (not over 60.0% of oesophageal length). Our SEM observations also revealed the presence of ca. 64-76 small conical denticles on each lip. In addition, Angusticaecum wuyiensis Wang, 1981, collected from Rana schmackeri Boettger (Amphibia: Anura) from Wuyi Mountain in Fujian Province, China was considered as a new synonym of S. numidica. The ITS and cox1 sequences of S. numidica were also sequenced for the first time and there is no nucleotide variability detected in both regions. The present supplementary morphological and molecular data (especially the ITS and cox1 sequences) obtained herein is extremely important and useful to determine the morphological variability, population genetics and phylogenetic position of S. numidica in the future.
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http://dx.doi.org/10.1515/ap-2018-0017DOI Listing
March 2018

Quantum mixed phases of a two-dimensional polarized degenerate Fermi gas in an optical cavity.

Sci Rep 2017 09 5;7(1):10568. Epub 2017 Sep 5.

State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan, 030006, China.

The coupling of ultracold fermions to a high-finesse optical cavity can result in novel many-body phenomena, and has attracted significant interests at present. Here we consider a realization of the Fermi-Dicke model with controllable parameters, based on a two-dimensional polarized degenerate Fermi gas coupled to an optical cavity. We analytically investigate the ground-state properties of such system under the mean-field approximation. We find the system can exhibit a rich phase diagram depending on the fermion-photon coupling strength and the atomic resonant frequency. Contrasting to the bosonic counterpart, a first-order quantum phase transition between the superradiant phase and the normal phase featuring two Fermi surfaces can occur for the weak atomic resonant frequency, and there is a unique mixed phase where this normal phase and the superradiant phase coexist. The experimental detection of our results is also discussed.
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http://dx.doi.org/10.1038/s41598-017-10686-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5585414PMC
September 2017

Spacial Energy Distribution Manipulation with Multi-focus Huygens Metamirror.

Sci Rep 2017 08 22;7(1):9081. Epub 2017 Aug 22.

Department of Microwave Engineering, Harbin Institute of Technology, Harbin, 150001, China.

Huygens metasurface is a planar array of crossed electric and magnetic dipoles, which provide specific surface current to tailor the electromagnetic field distribution. By changing the geometrical parameters of the proposed unit cell, the manipulation range of reflection phase can achieve 2π, while the amplitude of the reflection coefficient can keep above 0.993. Based on the designed Huygens meta-atoms, a novel multi-focus Huygens metamirror is proposed at microwave range in this paper. Utilizing the meta-atoms with the desired reflection phase distribution as calculated, the incident plane wave can be converged to designated points in any desired fashion including focal number, location and intensity distribution, which exhibits outstanding manipulation capability. Our research on Huygens metamirror provides a fascinating design of multi-focus imaging in microwave region, which makes it potential applications in antenna and imaging systems.
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http://dx.doi.org/10.1038/s41598-017-09474-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5567311PMC
August 2017

High-efficiency broadband excitation and propagation of second-mode spoof surface plasmon polaritons by a complementary structure.

Opt Lett 2017 Jul;42(14):2766-2769

A complementary structure based on coplanar waveguides (CPWs) with periodical etching slots is proposed to support spoof surface plasmon polaritons (SSPPs). In contrast to the traditional slotline-based complementary SSPP structure, a dispersion curve of the second mode by the proposed structure has a much lower starting point from the origin which exhibits greatly improved operating bandwidth. Moreover, tighter confinements of SSPPs in the region of small wave vectors corresponding to lower frequencies can be predicted from the dispersion analysis, which means enhancement of transmission efficiency. Then a simple and efficient transition structure with tapered CPWs and gradient slots is proposed to realize high-efficiency and broadband excitation of the second mode of SSPPs for the first time, to the best of our knowledge. Based on the proposed structure, a seamless connection between CPWs and the SSPP structure can be achieved. The measured insertion loss and return loss below 6.6 GHz is better than -0.86 and -13.62  dB, respectively. Furthermore, it can be seen from the measurement results that a 3 dB bandwidth ranges from 0 to 10.57 GHz, and the return loss is better than -10  dB from 0 to 8.96 GHz. The proposed structure can promote the development of plasmonic integrate circuits and functional devices at microwave frequencies.
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http://dx.doi.org/10.1364/OL.42.002766DOI Listing
July 2017

Analysis and modeling of Fano resonances using equivalent circuit elements.

Sci Rep 2016 08 22;6:31884. Epub 2016 Aug 22.

Microwave and Electromagnetic Laboratory, Harbin Institute of Technology, No.92, Xidazhi Street, Nangang District, Harbin City, Heilongjiang Province, China.

Fano resonance presents an asymmetric line shape formed by an interference of a continuum coupled with a discrete autoionized state. In this paper, we show several simple circuits for Fano resonances from the stable-input impedance mechanism, where the elements consisting of inductors and capacitors are formulated for various resonant modes, and the resistor represents the damping of the oscillators. By tuning the pole-zero of the input impedance, a simple circuit with only three passive components e.g. two inductors and one capacitor, can exhibit asymmetric resonance with arbitrary Q-factors flexiblely. Meanwhile, four passive components can exhibit various resonances including the Lorentz-like and reversely electromagnetically induced transparency (EIT) formations. Our work not only provides an intuitive understanding of Fano resonances, but also pave the way to realize Fano resonaces using simple circuit elements.
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http://dx.doi.org/10.1038/srep31884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4992960PMC
August 2016

Unconventional pairings of spin-orbit coupled attractive degenerate Fermi gas in a one-dimensional optical lattice.

Sci Rep 2015 Oct 7;5:14863. Epub 2015 Oct 7.

State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.

Understanding novel pairings in attractive degenerate Fermi gases is crucial for exploring rich superfluid physics. In this report, we reveal unconventional pairings induced by spin-orbit coupling (SOC) in a one-dimensional optical lattice, using a state-of-the-art density-matrix renormalization group method. When both bands are partially occupied, we find a strong competition between the interband Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) and intraband Bardeen-Cooper-Schrieffer (BCS) pairings. In particular, for the weak and moderate SOC strengths, these two pairings can coexist, giving rise to a new phase called the FFLO-BCS phase, which exhibits a unique three-peak structure in pairing momentum distribution. For the strong SOC strength, the intraband BCS pairing always dominates in the whole parameter regime, including the half filling. We figure out the whole phase diagrams as functions of filling factor, SOC strength, and Zeeman field. Our results are qualitatively different from recent mean-field predictions. Finally, we address that our predictions could be observed in a weaker trapped potential.
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http://dx.doi.org/10.1038/srep14863DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4595649PMC
October 2015

Ultrathin pancharatnam-berry metasurface with maximal cross-polarization efficiency.

Adv Mater 2015 Feb 28;27(7):1195-200. Epub 2014 Dec 28.

Department of Microwave Engineering, Harbin Institute of Technology, Harbin, 150001, China.

Novel ultrathin dual-functional metalenses are proposed, fabricated, tested, and verified in the microwave regime for the first time. The significance is that their anomalous transmission efficiency almost reaches the theoretical limit of 25%, showing a remarkable improvement compared with earlier ultrathin metasurface designs with less than 5% coupling efficiency. The planar metalens proposed empowers significant reduction in thickness, versatile focusing behavior, and high transmission efficiency simultaneously.
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http://dx.doi.org/10.1002/adma.201405047DOI Listing
February 2015

Facile route to produce chitin nanofibers as precursors for flexible and transparent gas barrier materials.

Biomacromolecules 2014 Dec 19;15(12):4614-20. Epub 2014 Nov 19.

School of Materials Science and Engineering and ‡School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.

Chitin is the second most abundant biopolymer in nature and has tremendous potential in renewable materials for packaging, energy storage, reinforced composites, and biomedical engineering. Despite attractive properties, including biodegradability, antibacterial activity, and high strength, chitin is not utilized widely due to strong molecular interactions, which make solubilization and processing difficult. We report a high pressure homogenization route to produce pure chitin nanofibers (ChNFs) starting with a mildly acidic aqueous dispersion of purified crab α-chitin. The well-dispersed ChNFs with diameter ∼20 nm do not form strong network structures under conditions explored herein and can be directly processed into useful materials, bypassing the need to dissolve the chitin. Dried ChNFs form pure self-standing chitin films with the lowest to-date reported O2 and CO2 permeabilities of 0.006 and 0.018 barrer, respectively. Combined with high flexibility and optical transparency, these materials are ideal candidates for sustainable barrier packaging.
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http://dx.doi.org/10.1021/bm501416qDOI Listing
December 2014
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