Phase Manipulation Research Articles

Six‐Mode Orbital Angular Momentum Generator Enabled by Helicity‐Assisted Full‐Space Metasurface with Flexible Manipulation of Phase, Polarization, and Spatial Information

AbstractVortex beam carrying orbital angular momentum (OAM) has been experiencing a research upsurge attributed to its excellent communication capability, which also boosts the development of the OAM technology and promotes the application of the OAM generator. However, most of the existing designs of the OAM generators can only produce a small number of diverse OAM modes, and restrict the channel capacity of single OAM generator. Herein, an appealing strategy of six‐mode OAM generator based on helicity‐assisted full‐space metasurface is proposed to generate up to six diverse OAM modes by altering the polarization state, illumination region, and incidence direction of incident waves. Significantly, the designed OAM generator has high communication security because of its great information entropy, and the generated OAM modes possess the characteristics of high purity and low crosstalk which result from the orthogonal polarization states and unequal deflection angles of produced vortex beams. A proof‐of‐concept prototype is constructed to corroborate the validity of our methodology, and the results of simulations and experiments are in excellent agreement with theoretical predictions. This fire‐new OAM generator will possess a promising application prospect in communication systems, and may also provide an efficacious method to design multifunctional devices.

Angular engineering strategy of an additional periodic phase for widely tunable phase-matched deep-ultraviolet second harmonic generation

Manipulation of the light phase lies at the heart of the investigation of light-matter interactions, especially for efficient nonlinear optical processes. Here, we originally propose the angular engineering strategy of the additional periodic phase (APP) for realization of tunable phase matching and experimentally demonstrate the widely tunable phase-matched second harmonic generation (SHG) which is expected for dozens of years. With an APP quartz crystal, the phase difference between the fundamental and frequency-doubled light is continuously angularly compensated under this strategy, which results the unprecedented and efficient frequency doubling at wavelengths almost covering the deep-UV spectral range from 221 to 332 nm. What’s more, all the possible phase-matching types are originally realized simultaneously under the angular engineering phase-matching conditions. This work should not only provide a novel and practical nonlinear photonic device for tunable deep-UV radiation but also be helpful for further study of the light-matter interaction process.

Ultrathin Dual‐Band Wide‐Angle Beam Scanning Metalens Based on High‐Efficiency Meta‐Atom

Metasurfaces composed of planar subwavelength‐scaled meta‐atoms demonstrate unprecedented wavefront manipulation capabilities. However, the wavelength‐dependent property of the metasurface could severely reduce the design freedom, and most metasurfaces require multilayer structure for high efficiency. Herein, a single‐layered‐substrate meta‐atom is proposed to achieve independent phase manipulations as well as high transmission efficiencies at two frequencies. Specifically, the full 2π phase coverages can be individually realized through rotating the corresponding resonators. As a proof‐of‐concept demonstration, a dual‐band high‐efficiency metalens with wide field‐of‐view (FoV) under the circular polarization incidence is simulated, fabricated and measured at Ka‐band for satellite communications. Both simulation and experimental results agree well with each other, demonstrating that wide scanning coverages of ±60° can be achieved at both 20 and 30 GHz. The proposed method can be a competitive candidate for designing dual‐band high‐efficiency meta‐devices.

Polariton-induced transparency in hybrid 2D-material hetero-nanostructure with multi-functions

In this work, we theoretically investigate the polariton-induced transparency (PoIT) phenomenon based on a hetero-nanostructure that possesses hybrid two-dimensional (2D) materials. The hetero-nanostructure consists of periodic hexagonal boron nitride (hBN) and graphene nanoribbons that are separated by a dielectric spacer. Consequently, the near-field coupling between hyperbolic phonon-polaritonic resonances on hBN ribbons and localized surface plasmon resonances on graphene ribbons leads to a transparent window in the mid-infrared region, where strong phase dispersion as well as slow light effect exist. Such hybrid-polariton induced transparency is dominated by electric dipole, and possesses reciprocity. It can be passively tailored by changing structural parameters, and actively tuned by shifting graphene Fermi level. Meanwhile, it is insensitive to the incident angle within a wider range, and rotating polarization angle of the incident wave leads to the excitation of edge phonon polaritons, which enriches the adjustability of this heterostructure. Furthermore, it can serve as a mid-infrared sensor to detect surrounding refractive index change, gas concentration, and molecular fingerprints. And introducing a metal reflector can easily turn it to be a wide-angle dual-band light absorber. Finally, we investigate the near-omnidirectional PoIT and polarization-dependent PoIT in the extended bilayer metasurface. This work has potential mid-infrared multifunctional applications in low-dimensional hybrid-polaritonic nanodevices for phase manipulation, slow light, sensing, and absorption.

Nondestructive Evaluation of Special Defects Based on Ultrasound Metasurface

We demonstrate the nondestructive evaluation by means of directional ultrasound emitted from a planar metasurface. The ultrasound metasurface is designed to generate the collimated and directional ultrasound efficiently in a planar configuration, which is endowed with the full-2π-range phase manipulation ability and high transmittance up to 80%. We employ the directional emission based on the ultrasound metasurface to innovate the traditional nondestructive evaluation methods, benefited from the freely controlled directivity and the superior fitness to sample surface of the planar metasurface. Merits of this innovative application are evidenced by the remarkable accuracy (higher than 98%) in the thickness evaluation, and precise detection (accuracy higher than 96%) of the special defect inside the V-shaped workpiece which is intractable to be inspected conventionally. The implementation of the metasurface-based directional ultrasound emission in the nondestructive evaluation bears the advantages of high coupling efficiency, superior fitness, high accuracy, and applicability to special defect, providing new solutions to the challenges in conventional defect detection and promotes the development in the nondestructive evaluation applications.

Spectral compression by phase doubling in second harmonic generation

In second harmonic generation, the phase of the optical field is doubled, which has important implications. Here, the phase-doubling effect is utilized to solve a long-standing challenge in the power scaling of single-frequency laser. (-π/2, π/2) binary phase modulation is applied to a single-frequency seed laser to broaden the spectrum and suppress the stimulated Brillouin scattering in a high-power fiber amplifier. The second harmonic of the phase-modulated laser returns to single frequency because the (-π/2, π/2) modulation is doubled to (-π, π) for the second harmonic. A compression-to-single-frequency rate as high as 95% is demonstrated in experiments limited by the electronic bandwidth of the setup. Such phase manipulation in wave-mixing processes may open up a new field of development in nonlinear optics and laser technology.

Implementation of Quantum Level Addressability and Geometric Phase Manipulation in Aligned Endohedral Fullerene Qudits.

Endohedral nitrogen fullerenes have been proposed as building blocks for quantum information processing due to their long spin coherence time. However, addressability of the individual electron spin levels in such a multiplet system of 4 S3/2 has never been achieved because of the molecular isotropy and transition degeneracy among the Zeeman levels. Herein, by molecular engineering, we lifted the degeneracy by zero-field splitting effects and made the multiple transitions addressable by a liquid-crystal-assisted method. The endohedral nitrogen fullerene derivatives with rigid addends of spiro structure and large aspect ratios of regioselective bis-addition improve the ordering of the spin ensemble. These samples empower endohedral-fullerene-based qudits, in which the transitions between the 4 electron spin levels were respectively addressed and coherently manipulated. The quantum geometric phase manipulation, which has long been proposed for the advantages in error tolerance and gating speed, was implemented in a pure electron spin system using molecules for the first time.

Implementation of Quantum Level Addressability and Geometric Phase Manipulation in Aligned Endohedral Fullerene Qudits

AbstractEndohedral nitrogen fullerenes have been proposed as building blocks for quantum information processing due to their long spin coherence time. However, addressability of the individual electron spin levels in such a multiplet system of 4S3/2 has never been achieved because of the molecular isotropy and transition degeneracy among the Zeeman levels. Herein, by molecular engineering, we lifted the degeneracy by zero‐field splitting effects and made the multiple transitions addressable by a liquid‐crystal‐assisted method. The endohedral nitrogen fullerene derivatives with rigid addends of spiro structure and large aspect ratios of regioselective bis‐addition improve the ordering of the spin ensemble. These samples empower endohedral‐fullerene‐based qudits, in which the transitions between the 4 electron spin levels were respectively addressed and coherently manipulated. The quantum geometric phase manipulation, which has long been proposed for the advantages in error tolerance and gating speed, was implemented in a pure electron spin system using molecules for the first time.

Methodology for assessing the influence of non­fluctuation interferences on the immunity of receiving discrete signals with multi­position phase manipulation

The work deals with the assessment of the impact of non-fluctuating interference on the interference immunity of the reception of discrete signals with multi-position phase manipulation. It was determined that the improvement of immunity under the influence of fluctuating interference and further scientific work on improving the efficiency of data transmission form a new, urgent scientific task to assess the impact of non-fluctuating interference on the immunity of TCM based on BFM signals. It was found that the main types of non-fluctuating interference that can affect the immunity of reception of discrete signals with multi-position phase manipulation are the following: harmonic interference, phase-manipulated interference, relayed interference, scannin interference, chaotic impulse interference, multiplicative interference. In order to reduce the impact on the immunity of TCM based on BFM signals, an appropriate methodology for assessing the impact of non-fluctuating interference on the immunity of reception of discrete signals with multi-position phase manipulation is proposed. The following procedure is proposed as the above methodology. Formation of TCM parameters of data transmission on the basis of BFM signals according to the functional purpose. Development of a TCM interference protection model for data transmission based on BFM signals under the influence of fluctuation interference, its implementation and evaluation of application effectiveness. Analysis of conditions and factors that can affect the formation of non-fluctuation disturbances on TCM based on BFM signals. Determination of the list of non-fluctuating interferences that can be formed under the influence of specified conditions and factors, in which the TCM of data transmission based on BFM signals functions. Evaluation of the impact of non-fluctuation interference on the effectiveness of TCM interference protection based on BFM signals. Development of recommendations for reducing the impact of non-fluctuational interference on the effectiveness of TCM interference protection based on BFM signals.

Development of smart fruit crops by genome editing

Plant genome editing tools as Zinc-Finger Nucleases (ZFNs), Trans Activator-Like Effector Nucleases (TALENs), and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) associated with Cas proteins are offering new possibilities for crop improvement and new insights for functional genomics. In this review, we discuss (i) the new findings in gene editing technologies, (ii) a comparison between them, and (iii) their applications for genetic analysis and manipulation of fruit crops. Different editing technologies, especially the CRISPR/Cas9 system, were successfully used in fruit crops such as apple, banana, cacao, citrus, grape, kiwifruit, and pear. Experimental designs used to analyze the efficiency of the CRISPR/Cas9 genome editor are presented, including manipulating key genes associated with carotenoid biosynthesis that could allow the development of complete albino and variegated phenotypes in some cultivars. The most recent outcomes of the application of genome-editing tools to improve the quality and yields of fruit crops, such as manipulation of juvenile phase and flowering period, gibberellin biosynthesis and generation of dwarf cultivars, ethylene biosynthesis, fruit ripening and parthenocarpy, development of resistant/tolerant cultivars to numerous pests and diseases are also summarized.

Independent Manipulation of Reflection Amplitude and Phase by a Single‐Layer Reconfigurable Metasurface

AbstractReconfigurable metasurfaces have attracted much attention in recent years due to their flexible capabilities of manipulating electromagnetic (EM) waves. However, most of the existing reconfigurable metasurfaces can only modulate either phase or magnitude, severely limiting the scope of their applications. Here, a novel metasurface is proposed that can simultaneously realize dynamic manipulation of reflection magnitude and phase. Such a metasurface is composed of periodic array of a single‐layer metallic structure loaded with two kinds of PIN diodes. By switching the state of one kind of PIN diodes, the 180° reflection phase difference can be obtained, meanwhile, the corresponding magnitude can be dynamically tuned at each phase state by changing the resistance of the other kind of PIN diodes. Compared with previously reported phase coding metasurface, the metasurface can not only control the directions of scattering beams, but also realize the tunable scattering intensity. In addition, it still can generate multibeam radiation with controllable power intensity and different beam number. The above versatile EM functionalities are demonstrated by full‐wave numerical simulation and experimental measurement at microwave frequencies. This study may pave a way to design smart materials and devices for multifunctional EM‐wave manipulation.

Tunable Phase Distribution of Liquid Metamaterial

A tunable liquid metamaterial (TLM) is proposed and demonstrated to possess phase tunability. TLM is composed of SiO2 nanopillars encapsulated with silicone oil. The phase of incident wavelength of 660 nm can be tuned 2π by elevating the height of SiO2 nanopillars to 1.65 μm. TLM shows high transmission intensity of 0.9. The phase manipulation is based on the liquid morphology, which is different from that by temperature and electrical methods. Herein, a TLM design is proposed to exhibit an actively tunable phase metamaterial and promote its application prospect. It provides the potential possibility of holography with high transmission intensity and shows actively tunable transmission phase to realize the tunable deflection angle, variable image, and varifocal metalens applications. This TLM design, an innovative idea for one kind of liquid metamaterial, is desirable to bring more possibilities to the tunable phase metamaterial. The adoptable electromagnetic spectrum of this design can also extend to the entire electromagnetic spectrum, such as microwave, terahertz (THz), infrared (IR), etc. The proposed TLM design provides an effective approach in tunable optoelectronics applications and a new direction for the future 3D stereoimaging and holographic projection applications.

Orthogonal manipulations of phase and phase dispersion in realization of azimuthal angle-resolved focusings

In conventional achromatic metasurfaces configurations where the engineering paths of phase and phase dispersion are the same, limited phase dispersion control range inevitably imposes a restriction on the broadband device size, which otherwise can be arranged in a periodic manner to achieve infinite size at a single wavelength. In addition to this, the adoption of geometric-phase structures imparts the orthogonal circular polarization conversion, whereas the birefringent propagation-phase structures bring an uncertain polarization state, thus resulting in an incomplete polarization conversion. In this study, we propose an azimuthal angle-resolved beam-deflection metasurface at the same polar angle with orthogonal phase and phase dispersion control paths. Periodic expansion is implemented to achieve unlimited device size along the phase control path and the broadband light is monotonously and azimuthally deflected to the designated polar angle with the delicate design along the dispersion path. In addition, the non-crossed polarized light arising from the incomplete geometric phase control would naturally separate from the cross-polarized light when adjusting the planar geometric parameters of the birefringent metaatoms to realize dispersion control. This design scenario may find applications in phased-array detection applications where beams are azimuthally swept to search targets at one polar angle.

Simultaneous control of amplitude and phase via shifting isotropy to anisotropy for achieving holographic meta-mirror

Although the emerging isotropic and uniaxially anisotropic metasurfaces have been demonstrated to provide diverse ways for achieving the manipulation of electromagnetic waves, the simultaneous control of both amplitude and phase with designated spin states is still an academic challenge, especially in microwave domain. Here, a paradigm of shifting meta-atom symmetry is proposed to push the development of this difficult issue. A split-ring structure with four identical gaps is applied as a proof-of-principle. By properly arranging the relative positions of four gaps, the electromagnetic characteristics of the meta-atom can be shifted from isotropy to anisotropy. The amplitude of the cross-polarized component of reflective electromagnetic wave is smoothly changed from 0 to 1. Assisted by the Pancharatnam-Berry phase principle, the phase manipulation of anisotropic meta-atom is governed by the control of pivoting. The phase gradient metasurface with uniform amplitude modulation is used as preliminary verification. Subsequently, the complex-amplitude holographic meta-mirrors are designed to promote the proposed paradigm to the application level. Numerical simulations and experimental demonstrations are carried out to reconstruct the holographic images of “B”, “I”, and “T”. Encouragingly, the proposed paradigm may be extended in the applications of circular polarized meta-devices and on-chip systems.

Acoustic Focusing with Intensity Modulation Based on Sub-Wavelength Waveguide Array

Acoustic focusing with intensity modulation plays an important role in biomedical and life sciences. In this work, we propose a new approach for simultaneous phase and amplitude manipulation in sub-wavelength coupled resonant units, which has not been reported so far. Based on the equivalent impedance and refractive index modulation induced by the change of geometry, arbitrary amplitude response from 0 to 1 and phase shift from 0 to 2π is realized. Thus, the acoustic focusing with intensity modulation can be achieved via waveguide array. Herein, the focal length can be adjusted by alternating the length of supercell, and the whole system can work in a broadband of 0.872f0–1.075f0. By introducing the coding method, the thermal viscosity loss is reduced, and the wavefront modulation can be more accurate. Compared with previous works, our approach has the advantages of simple design and broadband response, which may have promising applications in acoustic communication, non-destructive testing, and acoustic holography.

Phase manipulated two-mode entangled state from a phase-sensitive amplifier.

The phase manipulation of the two-mode entangled state, which can flexibly control the combination of quadrature components on demand, is important for continuous variable (CV) quantum information and quantum metrology. Here, we experimentally demonstrate the phase manipulation of entangled state by using a phase-sensitive amplifier (PSA) based on four-wave mixing (FWM) process. The entanglement with different phase space squeezing orientations can be generated by directly changing the phase of the PSA. Our scheme is concise and can be expanded to generate multi-parties entangled states on demand. Our results here pave the way to realize a phase-coded quantum key distribution protocol and squeezing-enhanced Raman spectroscopy.

Strain-driven phase manipulation of α- and κ-Ga2O3 by nanoepitaxial lateral overgrowth on embedded α-In2O3 submicron dots

Heteroepitaxy of corundum-structured α-Ga2O3 and intriguing ferroelectric κ-Ga2O3 is proven as an alternative strategy to solve current challenges in heat dissipation and large-scale productivity for Ga2O3-based power electronic devices, whereas the fundamental growth dynamics and phase control of metastable Ga2O3 are still far unexplored. In this Letter, we demonstrate the strategy of strain engineering for the in situ phase manipulation of metastable Ga2O3 by embedding α-In2O3 submicrometer dots. Phase transition is modulated by the surface coverage of α-In2O3 due to the competitive growth of κ-Ga2O3 upon α-In2O3 and the homoepitaxy of α-Ga2O3 on the exposed α-Ga2O3 seed region. Upon discrete α-In2O3 submicrometer dots with a low surface coverage, the growth undergoes a nano-scale epitaxial lateral overgrowth mode, in which the selective homoepitaxy of α-Ga2O3 is dominant, and embedded α-In2O3 serves as nano-masks to prevent the threading dislocation propagation into the lateral overgrown Ga2O3 layer. In comparison, κ-Ga2O3 is energetically favorable on the interconnected α-In2O3 submicrometer dots, which are driven by the in-plane tensile strain as probed by the geometric phase analysis of transmission electron microscopy. Phase manipulation by embedded sub micrometer dots allows us to deliver high-quality Ga2O3 with well-defined phases and to conceive advanced devices with ultra-low loss, high frequency, and memorizing functionality.

Topological materials discovery from crystal symmetry

Topological materials discovery has evolved at a rapid pace over the past 15 years following the identification of the first nonmagnetic topological insulators (TIs), topological crystalline insulators (TCIs) and 3D topological semimetals (TSMs). Most recently, through complete analyses of symmetry-allowed band structures — including the theory of topological quantum chemistry (TQC) — researchers have determined crystal-symmetry-enhanced Wilson-loop and complete symmetry-based indicators for nonmagnetic topological phases, leading to the discovery of higher-order TCIs and TSMs. The recent application of TQC and related methods to high-throughput materials discovery has revealed that over half of the known stoichiometric, solid-state, nonmagnetic materials are topological at the Fermi level, over 85 per cent of the known stoichiometric materials host energetically isolated topological bands, and just under two-thirds of the energetically isolated bands in known materials carry the stable topology of a TI or TCI. In this Review, we survey topological electronic materials discovery in nonmagnetic crystalline solids from the prediction of the first 2D and 3D TIs to the recently introduced methods that have facilitated large-scale searches for topological materials. We also discuss future venues for the identification and manipulation of solid-state topological phases, including charge-density-wave compounds, magnetic materials, and 2D few-layer devices. Solid-state materials have emerged as a platform for probing and manipulating topological phases of matter. This Review surveys topological materials discovery in nonmagnetic crystalline solids, focusing on the role of crystal symmetry and geometry in topological material predictions.

Control of angular dispersion in dielectric gratings for multifunctional wavefront shaping and dynamic polarization conversion

Compared with traditional optical elements, metasurfaces have shown unique advantages in multifunctionality encoded in different frequencies, polarization states, and orbital angular momentums. However, the study of metasurfaces with well-controlled functions under different incident angles is still in its infancy. Here we propose a general method to tailor the angular dispersion over the simplest binary dielectric grating in the transmission mode. We demonstrate that the angular response is strongly related to the number of waveguide modes inside the grating, so one can intentionally reduce or enhance the angular dispersion by controlling the number of waveguide modes. Independent phase manipulation over incident angles is experimentally demonstrated by a metalens with angle-dependent focus. The angular dispersion in orthogonal polarization states is further utilized to demonstrate angle-insensitive and angle-multiplexed wave plates. These devices with simple configuration and clear physics offer a general platform to expand the scope of beam manipulation over metasurfaces.

Broadband and wide-angle metamaterial absorber based on the hybrid of spoof surface plasmonic polariton structure and resistive metasurface.

Electromagnetic (EM) wave absorber with broad and robust absorption performance over wide incident angle range is persistently desired in specific applications. In this work, we propose and demonstrate a broadband and wide-angle metamaterial absorber (MA) based on a hybrid of stereo spoof surface plasmonic polariton (SSPP) structure and planar resistive metasurface. At first, we design a broadband SSPP absorber by adjusting the dispersion and loss of the artificial plasmonic structure (PS) simultaneously. Furthermore, owing to utilize its spatial phase manipulation ability, we integrate a resistive metasurface on top of the PS to construct a modified circuit analog (CA) absorber with a dispersive metamaterial spacer. The absorption mechanism of the hybrid structure is analyzed theoretically. The results indicate that the hybrid MA is equipped with broad and robust absorption performance over a wide incident angle range due to the synergistic absorption of the PS and metasurface. Finally, a prototype of the hybrid MA is fabricated by silk-printing technic and its absorption performances are measured. The experimental results can verify the theoretic ones and indicate that proposed hybrid MA can achieve 90% absorptivity from 3.9 GHz to 10.6 GHz with thickness of 7.0 mm, which is only 106% times of the ultimate thickness corresponding to the absorption performance of MA. In general, the concept and design offer a distinct approach of utilizing SSPP to design absorbers with excellent performances from radio frequency to optic band, which are promising for extensive applications.