Wei E. I. Sha

Wei E. I. Sha
Zhejiang University | ZJU · Department of Electronic Engineering

PhD
electromagnetics, optics, and optoelectronics

About

336
Publications
70,064
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
6,714
Citations
Introduction
electromagnetics, nano-optics, nanophotonics, plasmonics, photonic crystals, solar cells, nonlinear optics, metamaterials, metasurfaces, graphene, topological insulators, quantum optics.
Additional affiliations
March 2018 - March 2019
University College London
Position
  • Fellow
October 2017 - present
Zhejiang University
Position
  • Professor
September 2015 - December 2015
The University of Hong Kong
Position
  • ELEC8302 Nanophotonics
Education
July 2003 - July 2008
Anhui University
Field of study
  • Electromagnetics

Publications

Publications (336)
Article
Using photovoltaic cells as photovoltaic laser power converters (PLPCs) is a potential technology for long-range wireless power transfer. Intrinsic processes that limit the performance of PLPCs have not been fully investigated. Based on a thermodynamic model, we categorize and calculate the intrinsic losses in PLPCs. We use the experimental data of...
Article
The effects of gain and loss on the band structures of a bulk topological dielectric photonic crystal (PC) with C6v symmetry and the PC-air-PC interface are studied based on first-principle calculation. To illustrate the importance of parity-time (PT) symmetry, three systems are considered, namely the PT-symmetric, PT-asymmetric, and lossy systems....
Article
In this work, numerical solution to a general electromagnetic (EM) system is studied using a formalism based on the formulas for the E-B-A-φ formulas with different gauge conditions. The finite-difference time-domain (FDTD) method is employed to discretize these formulas. In addition, the convolutional perfectly matched layer (CPML) technique is su...
Article
Establishing and approaching the fundamental limit of orbital-angular-momentum (OAM) multiplexing are necessary and increasingly urgent for current multiple-input multiple-output research. In this work, we elaborate the fundamental limit in terms of independent scattering channels (or the degrees of freedom of scattered fields) through angular-spec...
Article
Effective degree of freedom (EDOF) of a multiple-input-multiple-output (MIMO) system represents its equivalent number of independent single-input-single-output (SISO) systems, which directly characterizes the communication performance. Traditional EDOF only considers single polarization, where the full polarized components degrade into two independ...
Preprint
Full-text available
Extremely large-scale multiple-input-multiple-output (XL-MIMO) is a promising technology to empower the next-generation communications. However, XL-MIMO, which is still in its early stage of research, has been designed with a variety of hardware and performance analysis schemes. To illustrate the differences and similarities among these schemes, we...
Preprint
Topological photonics has attracted increasing attention in recent years due to the unique opportunities it provides to manipulate light in a robust way immune to disorder and defects. Up to now, diverse photonic platforms, rich physical mechanisms and fruitful device applications have been proposed for topological photonics, including one-way wave...
Article
Metagratings manipulating the wavefront with a subwavelength volume have been widely explored in recent years for their potential applications in optical beam routers, such as laser beam splitters and combiners. Current metagratings are hampered from practical beam rerouting due to inhibitive computational load of engineering design and expensive n...
Preprint
Full-text available
In this letter, we consider transceivers with spatially-constrained antenna apertures of rectangular symmetry, and aim to improve of spatial degrees of freedom (DoF) and channel capacity leveraging evanescent waves for information transmission in near-field scenarios based on the Fourier plane-wave series expansion. The treatment is limited to an i...
Article
Full-text available
Topological photonics has attracted increasing attention in recent years due to the unique opportunities it provides to manipulate light in a robust way immune to disorder and defects. Up to now, diverse photonic platforms, rich physical mechanisms and fruitful device applications have been proposed for topological photonics, including one-way wave...
Article
A variety of novel orbital angular momentum (OAM) based communication or sensing systems have attracted much attention over the past decade, the superiority is brought about by nothing other than its orthogonality or vorticity. Plane spiral OAM (PSOAM) mode-group (MG) technique as a reconfigurable beamforming method can be used for building a multi...
Article
Full-text available
With the spread and application of the fifth generation (5G) of mobile communication technology, the number of 5G mobile phone users increase rapidly. The traditional safety standard of electromagnetic radiation of mobile phones was set two decades ago, in which a homogeneous specific anthropomorphic mannequin (SAM) head model with standardized siz...
Article
Full-text available
Terahertz photoconductive antenna (PCA) is an important device for generating ultrabroadband terahertz radiations, being applicable in various scenarios. However, the metallic electrodes in PCAs, a pair of coplanar strip lines (CSL), always produce horizontal electrode modes in a broad THz band, thus resulting in low directivity in the vertical dir...
Article
Full-text available
The calculation method for light emission efficiency splits external quantum efficiency (EQE) into internal quantum efficiency (IQE) and light extraction efficiency (LEE) independently. Consequently, the IQE connected to Purcell factor and the LEE are calculated separately. This traditional method ignores the interplays between the Purcell factor a...
Article
Topological valley photonics provides a unique way to manipulate the flow of light. In general, valley edge states that exhibit unidirectional propagation and are immune to defects and disorders could be realized at the interface between two valley photonic crystals with opposite valley Chern numbers. Herein, by merging the physics of valley edge s...
Preprint
Full-text available
The multi-user Holographic Multiple-Input and Multiple-Output Surface (MU-HMIMOS) paradigm, which is capable of realizing large continuous apertures with minimal power consumption and of shaping radio wave propagation at will, has been recently considered as an energy-efficient solution for future wireless networks. The tractable channel modeling o...
Article
Topological edge states exhibit low backscattering, unidirectional energy propagation, and robust immunity to sharp bends and defects in photonic topological waveguides. These properties of topological waveguides are expected to be applied in terahertz (THz) technology and expand to functional devices. Here, we introduce a line-defect into valley H...
Chapter
The nonlinear optical effects originating from the light-matter interaction under intense light excitations have enabled numerous novel applications, such as frequency conversion, all-optical modulation, and ultrafast optical switching. Recent years, the development of metamaterials, photonic crystals, and topological optics allow unconventional en...
Preprint
Full-text available
This article contains a digest of the theory of electromagnetism and a review of the transformation between inertial frames, especially under low speed limits. The covariant nature of the Maxwell's equations is explained using the conventional language. We show that even under low speed limits, the relativistic effects should not be neglected to ge...
Article
Full-text available
Innovative multiplexing technologies based on nano-optics for anti-counterfeiting have been proposed as overt (visible without tools) and covert (hidden and only visible with tools) technologies to secure products and make them difficult to counterfeit. However, most of these nano-optical anti-counterfeiting materials are metasurfaces and metamater...
Preprint
Full-text available
Metafibers expand the functionalities of conventional optical fibers to unprecedented nanoscale light manipulations by integrating metasurfaces on the fiber tips, becoming an emerging light-coupling platform for both nanoscience and fiber optics communities. Mostly exploring the isolated bare fibers, current metafibers remain as proof-of-concept de...
Article
Full-text available
This article contains a digest of the theory of electromagnetism and a review of the transformation between inertial frames, especially under low speed limits. The covariant nature of the Maxwell’s equations is explained using the conventional language. We show that even underlow speed limits, the relativistic effects should not be neglected to get...
Article
Metafibers expand the functionalities of conventional optical fibres to unprecedented nanoscale light manipulations by integrating metasurfaces on the fibre tips, becoming an emerging light-coupling platform for both the nanoscience and fibre optics communities. Current metafibers remain proof-of-concept demonstrations that mostly explore isolated...
Article
Full-text available
The canonical way to sustain photonic topological edge states relies on the interface formed by topologically trivial and nontrivial photonic crystals that share a common band gap to prevent the coupling of edge states from the radiation continuum of free space. Herein, we report a scheme to achieve bound topological edge states in the continuum at...
Preprint
Full-text available
Effective degree of freedom (EDOF) of a multiple-input-multiple-output (MIMO) system represents its equivalent number of independent single-input-single-output (SISO) systems, which directly characterizes the communication performance. Traditional EDOF only considers single polarization, where the full polarized components degrade into two independ...
Preprint
The multi-user Holographic Multiple-Input and Multiple-Output Surface (MU-HMIMOS) paradigm, which is capable of realizing large continuous apertures with minimal power consumption, has been recently considered as an energyefficient solution for future wireless networks, offering the increased flexibility in impacting electromagnetic wave propagatio...
Chapter
The vortex electromagnetic (EM) wave carring orbital angular momentum (OAM) that exhibits the phase distribution of the helical wave front. It is expected to provide a new dimension of the physical parameters for the multiplexing and manipulating EM wave, and bring a new opportunity to the traditional EMs. However, there are many obstacles in the p...
Article
Oxygen sensing attracts high research interest because it is applicable to early diagnosis and health monitoring. Herein, based on photonic crystals (PCs), a novel fluorescence enhancement effect (FEE) was explored to achieve highly sensitive and accurate oxygen detection. A flexible oxygen sensor was fabricated from heterogeneous polydimethylsilox...
Chapter
Electromagnetic (EM) waves can carry angular momenta that are decomposed into a spin and angular momenta. While circularly polarized waves take nonzero spin angular momentum (SAM), structured waves with helical wavefronts carry orbital angular momentum (OAM). Manipulation of OAM especially for the interaction between SAM and OAM obeys the angular m...
Article
Reducing carrier recombination and facilitating charge extraction at the interface is of great significance to improve the device performance of perovskite solar cells (PSCs) towards commercial use. However, there has been little work done concerning transportation and recombination mechanism at the interface of the metal electrode and the electron...
Preprint
Full-text available
The effects of gain and loss on the band structures of a bulk topological dielectric photonic crystal (PC) with $C_{6v}$ symmetry and the PC-air-PC interface are studied based on first-principle calculation. To illustrate the importance of parity-time (PT) symmetry, three systems are considered, namely the PT-symmetric, PT-asymmetric, and lossy sys...
Code
Generalized finite-difference method for Wilson loop calculation to characterize the topological invariant of non-Hermitian topological dielectric photonic crystals
Article
An orbital angular momentum (OAM) antenna based on chiral harmonic diffraction of spoof surface plasmon polaritons (SSPP) is demonstrated in this paper. Due to the diffraction of the helical wire, SSPP is transformed into the high-purity OAM mode. The operation frequency is determined by SSPP, and the topological charge is manipulated by modulating...
Article
This paper presents an efficient synthesis method for generating vortex beams based on donut-shaped orbital angular momentum (OAM) metasurfaces. It not only allows one to synthesize the vortex beam with an arbitrary combination of OAM modes and arbitrary mode energy distribution, but also avoids the undesired phase singularities in the conventional...
Article
Spatial division multiplexing using conventional orbital angular momentum (OAM) has become a well-known physical layer transmission method over the past decade. The mode-group (MG) superposed by specific single mode plane spiral OAM (PSOAM) waves has been proved to be a flexible beamforming method to achieve the azimuthal pattern diversity, which i...
Article
Full-text available
With the capability to manipulate the built‐in field in solar cells, ferroelectricity is found to be a promising attribute for harvesting solar energy in solar cell devices by influencing associated device parameters. Researchers have devoted themselves to the exploration of ferroelectric materials that simultaneously possess strong light absorptio...
Article
Full-text available
Stabilizing high-efficiency perovskite solar cells (PSCs) at operating conditions remains an unresolved issue hampering its large-scale commercial deployment. Here, we report a star-shaped polymer to improve charge transport and inhibit ion migration at the perovskite interface. The incorporation of multiple chemical anchor sites in the star-shaped...
Preprint
Full-text available
Establishing and approaching the fundamental limit of orbital angular momentum (OAM) multiplexing are paramountly important and increasingly urgent for current multiple-input multiple-output research. In this work, we elaborate the fundamental limit in terms of independent scattering channels (or degrees of freedom of scattered fields) through angu...
Article
Active metamaterials, i.e., coupled systems consist of metamaterials and active or gain media. Modelling the interaction between unconventional electromagnetic response in metamolecules and quantum dynamics of active media in active metamaterials requires the development of a unified and efficient semiclassical model. Here, we propose a semiclassic...
Conference Paper
Full-text available
A communication prototype of plane spiral OAM (PSOAM) mode-group (MG) based multiple-in-multiple-out (MIMO) system is built in a line-of-sight (LoS) scenario. Then, a long-range wireless transmission experiment is conducted at a distance of 30 m (beyond Rayleigh distance). The bit-error-rate (BER) performance proves the feasibility of the proposed...
Article
Nonlinear topological photonics, which explores topics common to the fields of topological phases and nonlinear optics, is expected to open up a new paradigm in topological photonics. Here, we demonstrate second-harmonic generation (SHG) via nonlinear interaction of double topological valley-Hall kink modes in all-dielectric photonic crystals (PhCs...
Article
Full-text available
Light harvesting is crucial for thin‐film solar cells. To substantially reduce optical loss in perovskite solar cells (PSCs), hierarchical light‐trapping nano‐architectures enable absorption enhancement to exceed the conventional upper limit and have great potential for achieving state‐of‐the art optoelectronic performances. However, it remains a g...
Article
Full-text available
In article number 2008091, Mingzhu Li, Wei E. I. Sha, Yanlin Song, and co‐workers design and fabricate colorful efficient perovskite solar cells (PSCs) incorporating moiré interference structures by imprinting with a commercial DVD disc. The light‐harvesting is boosted by elongation of the optical path and “folding” sunlight into the perovskite lay...
Chapter
Controlling electromagnetic waves in terms of frequency, amplitude, phase, polarization, and wavefront is fundamentally important in emerging applied science and applied engineering. Metamaterials and metastructural thin films (named metasurfaces) offer extraordinary ways to flexibly tune the properties of electromagnetic waves. The synthetic theor...
Preprint
Full-text available
Understanding and quantifying the main loss factors affecting the power conversion efficiency of perovskite solar cells are urgently needed. In this work, based on semiconductor physics, the expressions of bulk and surface recombination currents are analytically derived. Then taking the optical loss, series and shunt resistance losses, and bulk and...
Preprint
Full-text available
Spatial division multiplexing using conventional orbital angular momentum (OAM) has become a well-known physical layer transmission method over the past decade. The mode-group (MG) superposed by specific single mode plane spiral OAM (PSOAM) waves has been proved to be a flexible beamforming method to achieve the azimuthal pattern diversity, which i...
Article
The topological corner state (TCS) and topological edge state (TES) have created new approaches to manipulate the propagation of light. The construction of a topological coupled cavity-waveguide (TCCW) based on the TCS and TES is worth looking forward to, due to its research prospects in realizing high-performance micro-nano integrated photonic dev...
Preprint
Full-text available
Vortex beams carrying orbital angular momentum (OAM) have been widely applied in various electromagnetic, optical, and quantum systems. A tailored OAM spectrum composed of several specific modes as expected holds a promise for expanding the degrees of freedom of the systems. However, such a broadband high-purity tailored spectrum is difficult to be...
Article
Full-text available
Rapid progress in nonlinear plasmonic metasurfaces enabled many novel optical characteristics for metasurfaces, with potential applications in frequency metrology [Zimmermann et al. Opt. Lett. 29:310 (2004)], timing characterization [Singh et al. Laser Photonics Rev. 14:1 (2020)] and quantum information [Kues et al. Nature. 546:622 (2017)]. However...
Article
Full-text available
The cover image shows a shape‐tailored metasurface with the triangular‐lattice arrangement of meta‐atoms, as demonstrated in article number 2001711 by Ling‐Jun Yang, Sheng Sun, and Wei E. I. Sha. The shape‐related manipulation of metasurfaces provides a promising route to control the amplitude of the reflection field, enabling further manipulation...