arXiv subjects

Haitao Jiang

Publications and source records attributed to Haitao Jiang.

29 records · Page 2Linked to original sources

arXiv2020

Experimental Realization of Near-Field Photonic Routing with All-Electric Metasources

The spatially confined evanescent microwave photonics have been proved to be highly desirable in broad practical scenarios ranging from robust information communications to efficient quantum interactions. However, the feasible applications of these photonics modes are limited due to the lack of fundamental understandings and feasible directional coupling approaches at sub-wavelengths. Here, we experimentally demonstrate the efficient near-field photonic routing achieved in waveguides composed of two kinds of single-negative metamaterials. Without mimicking the polarization features, we propose all-electric near-field metasource in subwavelength scale and exemplify its near-field functions like Janus, Huygens and spin sources, corresponding to time-reversal, parity-time and parity symmetries of its inner degree of freedom. Our work furthers the understandings about optical near-field symmetry and feasible engineering approaches of directional couplings, which would pave the way for promising integrated mircrowave photonics devices.

physics.optics↗

arXiv2019

Hyperbolic Metamaterials: From Dispersion Manipulation to Application

Manipulating the property of iso-frequency contour (IFC) will provide a powerful control for the interaction between light and matter. Importantly, hyperbolic metamaterials (HMMs), a class of artificial anisotropic materials with hyperbolic IFC have been intensively investigated. Because of the open dispersion curves, HMMs support propagating high-k modes and possess enhanced photonic density of states. As a result, HMMs can be utilized to realize hyper-lens breaking the diffraction limit, meta-cavity laser with subwavelength scale, high sensitivity sensor, long-range energy transfer and so on. In order to make it easier for people who are about to enter this burgeoning and rapidly developing research field, this tutorial article not only introduces the basic physical properties of HMMs, but also discusses the dispersion manipulation of HMMs and HMM-based structures such as hypercrystals. The theoretical methods and experimental platforms are given in this tutorial. Finally, some potential applications associated with hyperbolic dispersion are also introduced

physics.optics↗

arXiv2018

Seeing Topological Order and Band Inversion in Optical Diatomic Chain

Recent realizations of exotic topological states in condensed matter and cold atoms have advanced the exploration for topological characteristics, such as invariant topological orders and band inversion. Here we construct a 1D optical diatomic system made of split ring resonators with electric-magnetic couplings to implement the topological features. We experimentally measure the dispersion relationship and sub-lattice pseudo-spin vectors by detecting field strength distributions, which determines the accompanying winding number of bulk band as the topological order. The sub-lattice pseudo-spin vector inversion observed at band-edges evidences the band inversion. We further reconfirm the band-inversion-induced topological phase transition by measuring the symmetry exchanges at band-edges. These results have shown the great potential of split ring resonator platform to experimentally explore the advanced topological characteristics, such as high winding numbers or even high Chern numbers in more exotic setups.

physics.optics↗

arXiv2018

Significant enhancement of magneto-optical effect in one-dimensional photonic crystals with magnetized epsilon-near-zero defect

Nonreciprocal (NOR) transmission with magneto-optical materials plays a critical role in a broad range of applications, such as optical isolation, all-optical signal processing, and integrated photonic circuits. The underlying mechanism is that a static magnetic field can break the time-reversal symmetry in the presence of magneto-optical materials. However, the typical NOR devices usually need a large size because the weak magneto-optical activity of materials. Here, our theoretical investigations show that the NOR transmission can be obtained in the one-dimensional photonic crystal with a magnetized epsilon-near-zero (ENZ) defect due to strong field localization in the ENZ medium. The inherent weak magneto-optical activity is significantly enhanced in ENZ medium. In our configuration, the wavelength shift of transmission peaks along two opposite incident directions can be up to 100 times higher than that in the case that the defect layer is a normal bismuth iron garnet. Such results will provide a new degree to design novel magneto-optical devices with small size, and may open novel routes to exploit advanced materials for steering the electromagnetic waves in nano-scale structures.

physics.optics↗

arXiv2018

Observation of the topological edge state in X-ray band

The possibility of obtaining robust edge state of light by mimicking the topological properties of solid state system, have brought a profound impact on optical sciences. With the advent of high-brilliance, accelerator-driven light sources such as storage rings or X-ray lasers, it has become attractive to extend the concept of optical topological manipulation to the X-ray regime. In this paper, we theoretically proposed and experimentally demonstrated the topological edge state at the interface of two photonic crystals having different band-gap topological characteristics for X-ray. Remarkably, this topologically protected edge state is immune to the weak disorder in form of the thickness disorder and strong disorder in form of the positional disorder of layers in the structure, as long as the zero-average-effective-mass condition is satisfied. Our investigation therefore brings the topological characteristics to the X-ray regime, provides new theoretical tools to study X-ray optics and may pave way to exploit some important potential applications, such as the high efficiency band filter in X-ray band.

physics.app-ph↗

arXiv2018

Actively controlling the topological transition of dispersion based on electrically controllable metamaterials

Topological transition of the iso-frequency contour (IFC) from a closed ellipsoid to an open hyperboloid, will provide unique capabilities for controlling the propagation of light. However, the ability to actively tune these effects remains elusive and the related experimental observations are highly desirable. Here, tunable electric IFC in periodic structure which is composed of graphene/dielectric multilayers is investigated by tuning the chemical potential of graphene layer. Specially, we present the actively controlled transportation in two kinds of anisotropic zero-index media containing PEC/PMC impurities. At last, by adding variable capacitance diodes into two-dimensional transmission-line system, we present the experimental demonstration of the actively controlled magnetic topological transition of dispersion based on electrically controllable metamaterials. With the increase of voltage, we measure the different emission patterns from a point source inside the structure and observe the phase-transition process of IFCs. The realization of actively tuned topological transition will opens up a new avenue in the dynamical control of metamaterials.

physics.optics↗

arXiv2018

Zak phase and band inversion in dimerized one-dimensional locally resonant metamaterials

Zak phase, which refers to the Berry's phase picked up by a particle moving across the Brillouin zone, characterizes the topological properties of Bloch bands in one-dimensional periodic system. Here the Zak phase in dimerized one-dimensional locally resonant metamaterials is investigated. It is found that there are some singular points in the bulk band across which the Bloch states contribute π to the Zak phase, whereas while in the rest of the band the contribution is nearly zero. These singular points associated with zero reflection are caused by two different mechanisms: the dimerization-independent anti-resonating of each branch, and the dimerization-dependent destructive interference in multiple backscattering. The structure undergoes a topological transition point in the band structure where the band inverts and the Zak phase, which is determined by the numbers of singular points in the bulk band, changes following a shift in dimerization parameter. Finally, the interface state between two dimerized metamaterial structures with different topological property in the first band gap is demonstrated experimentally. The quasi-one-dimensional configuration of the system allows one to explore topology-inspired new methods and applications in the sub-wavelength scale.

cond-mat.mes-hall↗

arXiv2018

Enhancement of Electromagnetically Induced Transparency in Metamaterials Using Long Range Coupling Mediated by a Hyperbolic Material

Near-field coupling is a fundamental physical effect, which plays an important role in the establishment of classical analog of electromagnetically induced transparency (EIT). However, in a normal environment the coupling length between the bright and dark artificial atoms is very short and far less than one wavelength, owing to the exponentially decaying property of near fields. In this work, we report the realization of a long range EIT, by using a hyperbolic metamaterial (HMM) which can convert the near fields into high-k propagating waves to overcome the problem of weak coupling at long distance. Both simulation and experiment show that the coupling length can be enhanced by nearly two orders of magnitude with the aid of a HMM. This long range EIT might be very useful in a variety of applications including sensors, detectors, switch, long-range energy transfer, etc.

physics.optics↗

arXiv2018

Experimental demonstration of the robust end state in a split-ring-resonator chain

One of the fascinating topological phenomena is the end state in one dimensional system. In this work, the topological photonics in the dimer chains composed by the split ring resonators are revealed based on the Su-Schrieffer-Heeger model. The topologically protected photonic end state is observed directly with the in situ measurements of the local density of states in the topological nontrivial chain. Moreover, we experimentally demonstrate that the end state localized at both ends is robust against a varied of perturbations, such as loss and disorder. Our results not only provide a versatile platform to study the topological physics in photonics but also may have potential applications in the robust communication and power transfer.

physics.optics↗

arXiv2017

Photonic Spin Hall Effect in Waveguides Composed of Two Types of Single-Negative Metamaterials

The polarization controlled optical signal routing has many important applications in photonics such as polarization beam splitter. By using two-dimensional transmission lines with lumped elements, we experimentally demonstrate the selective excitation of guided modes in waveguides composed of two kinds of single-negative metamaterials. A localized, circularly polarized emitter placed near the interface of the two kinds of single-negative metamaterials only couples with one guided mode with a specific propagating direction determined by the polarization handedness of the source. Moreover, this optical spin-orbit locking phenomenon, also called the photonic spin Hall effect, is robust against interface fluctuations, which may be very useful in the manipulation of electromagnetic signals.

cond-mat.mes-hall↗

arXiv2011

Comparing Pedigree Graphs

Pedigree graphs, or family trees, are typically constructed by an expensive process of examining genealogical records to determine which pairs of individuals are parent and child. New methods to automate this process take as input genetic data from a set of extant individuals and reconstruct ancestral individuals. There is a great need to evaluate the quality of these methods by comparing the estimated pedigree to the true pedigree. In this paper, we consider two main pedigree comparison problems. The first is the pedigree isomorphism problem, for which we present a linear-time algorithm for leaf-labeled pedigrees. The second is the pedigree edit distance problem, for which we present 1) several algorithms that are fast and exact in various special cases, and 2) a general, randomized heuristic algorithm. In the negative direction, we first prove that the pedigree isomorphism problem is as hard as the general graph isomorphism problem, and that the sub-pedigree isomorphism problem is NP-hard. We then show that the pedigree edit distance problem is APX-hard in general and NP-hard on leaf-labeled pedigrees. We use simulated pedigrees to compare our edit-distance algorithms to each other as well as to a branch-and-bound algorithm that always finds an optimal solution.

cs.DS↗