作者机构：
[He-Xiu Xu; Yanzhao Wang; Chaohui Wang] Department of Electronic Science and Technology, Air force Engineering University, Xi'an, 710051 China;[Shiwei Tang] Department of Physics, Faculty of Science, Ningbo University, Ningbo, 315211 China;[Xiaohui Ling] College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang, 421002 China;[Jiafeng Zhou] Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, L69 3GJ UK;[Guangwei Hu; Menghua Jiang] Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583 Singapore
关键词：
dual mode;dynamic and geometric phase;multiplexed metasurfaces;spin decoupling;wavefront control
摘要：
We theoretically propose the realization of a three-dimensional (3D) spin Hall effect (SHE) of light by tightly focusing a linearly polarized light. Owing to the spin-orbital interaction in focusing, the left and right circularly polarized components of light are partly converted into each other, acquiring opposite vortex phases. As the superposition of the vortex and the initial vortex-free light, the two polarized components exhibit spiral intensity patterns which rotate oppositely around the propagation axis. Consequently, the two spin components are distributed alternatively in both the azimuthal and the longitudinal directions, leading to a 3D array of split spin components, and the transverse intensity is also spit asynchronously. Moreover, that array is rotatable by the incident polarization, and the longitudinal spacing in the array can be controlled by the numerical aperture of the lens. The 3D SHE of light finds an additional degree of freedom available to control the spin state of the photon, which may be valuable in optical manipulation and quantum information.
摘要：
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. However, the precise and real-time detection of the reaction rate remains challenging due to its fast and dynamical process. In this paper, the photonic spin Hall effect is proposed to realize the ultrasensitive and real-time detection of the reaction rate of sucrose hydrolysis. By incorporating with quantum weak measurement, the photonic spin-Hall shift acts as the measurement pointer, and the optical rotation in the process of sucrose hydrolysis acts as the postselection state. The high measurement resolution with 1.25 × 10−4 degree is achieved due to the weak-value amplification in quantum weak measurement which outperforms the standard polarimeter. In our scheme, the amplified measurement pointer is real-time monitoring the chemical reaction process. It does not involve any mechanical adjustment of optical elements once the experimental setup is established and thereby realizes a real-time detection of the dynamic chemical reaction.
摘要：
It has been known that an optical vortex with a topological charge +/- 2 can be generated as a circularly polarized (CP) light beam propagates in a bulk uniaxial crystal, but its physical origin remains obscure which also hinders its practical applications. Here, through a rigorous full-wave analyses on the problem, we show that, as a CP beam possessing a particular spin (handedness) propagates inside a uniaxial crystal, two beams with opposite spins can be generated caused by the unique spin-sensitive light-matter interactions in the anisotropic medium. Flipping the spin can offer the light beam an vortex phase with a topological charge of +/- 2 owing to the Pancharatnam-Berry mechanism, with efficiency dictated by the material properties of the uniaxial medium and the topological structure of the beam itself. With its physical origin fully uncovered, we finally discuss how to improve the efficiency of such effect, and compare the mechanisms of vortex generations in different systems. Our findings not only provide deeper understandings on such an intriguing effect, but also shed light on other spin-orbit-interaction-induced effects. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
摘要：
Spin-controlled vortex generation is a manifestation of the spin-orbit interaction (SOI) of light, which has been extensively studied in Pancharatnam-Berry geometric phase elements in recent years. The SOI under the normal incidence of a light beam at a sharp interface, also shown by a spin-dependent vortex, has attracted little attention, except for a few exceptions. Here, we establish a Fresnel Jones matrix to fully describe the dynamics of beam reflection and refraction at sharp interfaces under normal incidence. It is pointed out that the vortex phase originates from the topological structure of the beam itself and is essentially a spin-redirection Berry phase. Although the geometric phase in Pancharatnam-Berry elements comes from the anisotropy of the external material, which shows a fundamental difference, they are the same in form. We then give a comparative study of the two kinds of SOI, and reveal the intrinsic connection and difference between them. Our research not only establishes a unified framework to describe the two SOIs, but also offers a new perspective for studying the SOIs in other physics.
摘要：
Photonic spin Hall effect (PSHE) in momentum space can lead to a giant spin-dependent splitting (SDS). However, the SDS in momentum space increases linearly with beam propagation distance, which limits its applications. In this work, a simple method is proposed to transform the PSHE from momentum space to position space. We first theoretically analyze the feasibility of the transformation. The results show that the transformation can be realized when a light wave passes through two identical Pancharatnam–Berry phase metasurfaces. Then an experimental setup is established to verify the theoretical results. Through rational design of the optical path, only one metasurface is needed to complete the transformation of PSHE from momentum space to position space. The experimental results agree well with theoretical calculations. We believe that these results are helpful for the design of photonics devices based on PSHE.
摘要：
In high-power laser systems for inertial confinement fusion, hot images may be intense enough to damage expensive optical components. Basing on split-step fast-Fourier-transform algorithm, the intensity and location of hot images of a spectrally dispersed sinusoidal phase modulated laser beam is numerically investigated. It is found that, the time-average intensity of hot image firstly decreases monotonically with the modulation depth and eventually reaches a certain minimum, then increases slowly and reaches a saturated value; in addition, with the modulation frequency and the grating dispersion coefficient increasing, the time-average intensity of hot image decreases generally; while the location of hot image always does not change. Finally, the influence of the distance from the obscuration to the nonlinear optical element on the suppression effect of spectral dispersion of sinusoidal phase modulated light on formation of hot images is discussed. The result is helpful to appropriately choose parameters of the spectrally dispersed sinusoidal phase modulated light to minimize the threat of optical damage of hot image and improve the performance of high- power laser system.
关键词：
Photonic spin hall effect;Spin-dependent shift;Rotation symmetry;Pancharatnam-Berry phase
摘要：
Photonic spin Hall effect (SHE) manifests itself as spin-dependent shift or splitting of a light beam, which is derived from spin-orbit interactions, and can be realized by breaking the rotation symmetry of light-matter interaction systems. Here, we demonstrate the observation of a photonic SHE by breaking the rotation symmetry of the optical field, while keeping the rotation symmetry of the inhomogeneous waveplate. The inhomogeneous waveplate constructed by dielectric nanostructures, introduces a spin-dependent Pancharatnam-Berry phase to the two spin components of the input beam, i.e., the left- and right-circular polarization components acquire exactly opposite vortex phases. During beam propagation, they experience opposite azimuthal rotations, and induce a four-lobe spin-dependent splitting in the azimuthal direction. In addition, the spin-dependent splitting becomes more evident upon beam propagation, and can be enhanced by increasing the topological orders of the nanostructures. For comparison, we also examine that no spin-dependent splitting can be observed when keeping the rotation symmetry of the incident optical field.
摘要：
Parabolic phase is commonly utilized for concave or convex metalens. Here, we report for the first time using such approach for determinant diffusion of scattering waves in wide incident angles by arranging parabolic-phased subarrays in arbitrary coding sequences. To engineer multi-spectrum polarization-dependent bifunctional scatterings, multi-mode anisotropic meta-atoms are utilized without polarization cross-talking. For verification, two proof-to-concept coding metasurfaces are designed, fabricated and measured at microwave regime. Numerical and experimental results show that the -10 dB backscatter radar cross-section (RCS) reduction is clearly observed in C, X and Ku band. Moreover, the diffusion behavior can be engineered dual-polarized and even bifunctional by integrating vortex scattering. Our findings, free of time-consuming optimizations, opened a rapid, easy but very efficient way for stealth applications under bistatic detection.
期刊：
Results in Physics,2018年9:215-217 ISSN：2211-3797
通讯作者：
Tang, Shiqing
作者机构：
[Dai, Zhiping; Tang, Shiqing; Ling, Xiaohui] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.
通讯机构：
[Tang, Shiqing] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.
关键词：
Hollow Gaussian beam;Strongly nonlocal media;Propagation property;Off-waist incident case
摘要：
In this paper, the propagation properties of hollow Gaussian beams (HGBs) are discussed in detail when they are off-waist incident in strongly nonlocal media. A set of mathematic expressions are given to describe the evolutions of the beam intensity, the beam width, and the real beam radius. Numerical simulations are carried out to illustrate these propagation properties depended on the off-waist incidence. It is found that a HGB always periodically transforms its transverse patterns during propagation. Accordingly, the beam width and the real beam radius are also periodic during propagation.
摘要：
In this work, we theoretically propose an optical biosensor (consists of a BK7 glass, a metal film, and a graphene sheet) based on photonic spin Hall effect (SHE). We establish a quantitative relationship between the spin-dependent shift in photonic SHE and the refractive index of sensing medium. It is found that, by considering the surface plasmon resonance effect, the refractive index variations owing to the adsorption of biomolecules in sensing medium can effectively change the spin-dependent displacements. Remarkably, using the weak measurement method, this tiny spin-dependent shifts can be detected with a desirable accuracy so that the corresponding biomolecules concentration can be determined.
