- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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High order perfect optical vortex shaping
摘要： We proposed a method based on high-order Bessel–Gaussian beam to improve quality and intensity profile of high-order perfect optical vortex (POV) array under tight focusing condition. By using this method, parameters of POV could be controlled such as uniform ring width, adjustable ring diameter as well as controllable position, numbers and topological charges. A quality factor was proposed for assessing POV with different ring diameter and different topological charge. Comparing with the conventional method for generating POV, the optimal high-order POV carry uniform intensity distribution and the same ring width and diameter, which may enlarge the application on optical manipulation of multiple particles, large capacity optical storage and multiplexing optical vortex communication.
关键词： Tight focusing,Optics vortex,Phase modulation
更新于2025-09-04 15:30:14
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Shaping the Wavefront of Incident Light with a Strong Robustness Particle Swarm Optimization Algorithm
摘要： We demonstrate a modified particle swarm optimization (PSO) algorithm to effectively shape the incident light with strong robustness and short optimization time. The performance of the modified PSO algorithm and genetic algorithm (GA) is numerically simulated. Then, using a high speed digital micromirror device, we carry out light focusing experiments with the modified PSO algorithm and GA. The experimental results show that the modified PSO algorithm has greater robustness and faster convergence speed than GA. This modified PSO algorithm has great application prospects in optical focusing and imaging inside in vivo biological tissue, which possesses a complicated background.
关键词： wavefront shaping,particle swarm optimization,optical focusing,genetic algorithm,digital micromirror device
更新于2025-09-04 15:30:14
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[IEEE 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Athens, Greece (2018.7.4-2018.7.6)] 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Performance of Time-Reversal for Indoor Communications
摘要： In this paper, we study the performance of time-reversal technique for wireless data transmission in indoor environment. The principle of operation of this technique is to use the time-reversed channel impulse response of the propagating medium in order to modulate the data to be sent. This technique allows reducing the effect of multi-paths and the delay spread of the received signal at the position of the receiver. The coherence bandwidth of the channel is increased. Therefore, for a targeted bit error rate, the data rate which can be sent over the channel will be increased theoretically when the time-reversal technique is used. Measurements results carried out in an indoor environment are presented and analyzed. These results are promoting and show the possibility to create independent channels with multiple users.
关键词： indoor measurement,time-reversal,spatial and temporal focusing,MISO,wireless data transmission
更新于2025-09-04 15:30:14
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Inverse photonic design of functional elements that focus Bloch surface waves
摘要： Bloch surface waves (BSWs) are sustained at the interface of a suitably designed one-dimensional (1D) dielectric photonic crystal and an ambient material. The elements that control the propagation of BSWs are defined by a spatially structured device layer on top of the 1D photonic crystal that locally changes the effective index of the BSW. An example of such an element is a focusing device that squeezes an incident BSW into a tiny space. However, the ability to focus BSWs is limited since the index contrast achievable with the device layer is usually only on the order of Δn≈0.1 for practical reasons. Conventional elements, e.g., discs or triangles, which rely on a photonic nanojet to focus BSWs, operate insufficiently at such a low index contrast. To solve this problem, we utilize an inverse photonic design strategy to attain functional elements that focus BSWs efficiently into spatial domains slightly smaller than half the wavelength. Selected examples of such functional elements are fabricated. Their ability to focus BSWs is experimentally verified by measuring the field distributions with a scanning near-field optical microscope. Our focusing elements are promising ingredients for a future generation of integrated photonic devices that rely on BSWs, e.g., to carry information, or lab-on-chip devices for specific sensing applications.
关键词： focusing elements,scanning near-field optical microscope,integrated photonic devices,Bloch surface waves,photonic design
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Lens Antennas Focus Determination Using Full-Wave Simulation
摘要： The determination of the focal length in lens antennas is usually difficult. This work applies the potential of a code used for the implementation of a full-wave, two-dimensional (2D) electromagnetic simulator based on the method of moments (MoM), which allows solving in very short time electromagnetic scattering problems using the two-dimensional (2D) Lippmann-Schwinger equation [1-3]. The results obtained with this code of hyperbolic lenses and biconvex lenses allow determining the location of the focus and comparing them with theoretical analytical results.
关键词： focusing,lens,millimeter-wave antennas,simulation
更新于2025-09-04 15:30:14
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Fabrication of a precise ellipsoidal mirror for soft X-ray nanofocusing
摘要： In X-ray focusing, grazing incidence mirrors offer advantages of no chromatic aberration and high focusing ef?ciency. Although nanofocusing mirrors have been developed for the hard X-ray region, there is no mirror with nanofocusing performance in the soft X-ray region. Designing a system with the ability to focus to a beam size smaller than 100 nm at an X-ray energy of less than 1 keV requires a numerical aperture larger than 0.01. This leads to dif?culties in the fabrication of a soft X-ray focusing mirror with high accuracy. Ellipsoidal mirrors enable soft X-ray focusing with a high numerical aperture. In this study, we report a production process for ellipsoidal mirrors involving mandrel fabrication and replication processes. The fabricated ellipsoidal mirror was assessed under partial illumination conditions at the soft X-ray beamline (BL25SU) of SPring-8. A focal spot size of less than 250 nm was con?rmed at 300 eV. The focusing tests indicated that the proposed fabrication process is promising for X-ray mirrors that have the form of a solid of revolution, including Wolter mirrors.
关键词： soft X-ray,fabrication process,ellipsoidal mirror,nanofocusing,X-ray focusing
更新于2025-09-04 15:30:14
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Focusing and Super-Resolution with Partial Cloaking Based on Linear-Crossing Metamaterials
摘要： Manipulating the topological property of iso-frequency contour (IFC) will provide a unique control for the interaction between light and matter, such as increased rates of spontaneous emission and negative refraction. Different from the aforementioned topological transition that is realized by controlling the in-plane anisotropic electromagnetic parameters in a two-dimensional case, we theoretically propose and experimentally demonstrate another topological transition by tuning the vertical electromagnetic parameters of the anisotropic medium. Specially, the critical IFC in this transition corresponds to two intersecting lines and can be called linear-crossing metamaterial (LCMM). Based on the directional propagation and negative refraction in LCMM, we demonstrate the focusing and super-resolution with partial cloaking in transmission-line-based LCMMs. The realization of LCMM will open up another avenue for controlling light propagation and verifying unusual phenomena involving zero-index media and hyperbolic metamaterials.
关键词： partial cloaking,topological transition,super-resolution,linear-crossing metamaterial,focusing,iso-frequency contour
更新于2025-09-04 15:30:14
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[IEEE 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Erlagol (Altai Republic), Russia (2018.6.29-2018.7.3)] 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Examination of Physical Phenomena and Processes in the Magnetophotonic Composite Media. Magnetophotonics Material Medium
摘要： The development of radioelectronics and informative–and–communicative technologies of the XXI century is associated with the transmission of ever increasing volume of data and is oriented to use of subTHz and THz bands – SHF, EHF, and HHF (0.1 – 10 THz). Elements and devices of these bands can be conditionally divided into 2 levels: up to 1THz electronic equipments are effectively uses, over 1 THz –are photonic devices. The development of photonic technologies is of increasing importance both in the telecommunicative and in the space communication systems. In this report the physical phenomena and processes occurring in magnetooptical (magnetophotonic) composite material media capable of optimally ensuring their efficiency have been investigated to create new element baseline for domestic radioelectronics. The creation of new–generation functional devices capable of operating in subTHz and THz frequency bands will entail the rapid development of telecommunications.
关键词： Kerr effect,laser radiation,magnetophotonics,Maxwell's equations,self–focusing of light,nonlinear photonic media,Green's functions,Nanophotonics,current harmonics
更新于2025-09-04 15:30:14
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Subwavelength focusing of a cylindrically symmetric plano-concave lens based on a one-dimensional Thue–Morse photonic quasicrystal
摘要： A cylindrically symmetric plano-concave lens based on a one-dimensional (1D) Thue–Morse photonic quasicrystal (PQC) is proposed. Sub-wavelength focusing characteristics with an incident cylindrical vector beam are investigated. Numerical results reveal that the lens can exhibit polarization-independent, high-resolution, and low-side-lobe characteristics, simultaneously for near-?eld and non-near-?eld. Furthermore, the lens can achieve perfect focusing and size-independent characteristics with equal-proportion scaling of the size of the lens at the corresponding center frequency. The focusing mechanisms of the lens are explained by analyzing the transmission spectrum, dispersion relation of a 1D periodic photonic crystal, and transmission spectrum of the 1D Thue–Morse PQC.
关键词： cylindrical vector beam,Subwavelength focusing,plano-concave lens,photonic quasicrystal
更新于2025-09-04 15:30:14