- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Vortex Dynamics and Optical Vortices || Ultrashort Extreme Ultraviolet Vortices
摘要： Optical vortices are very attractive because they transport a well-defined orbital angular momentum (OAM) associated with the singularity of the beam. These singular beams, commonly generated in the optical regime, are used in a wide range of applications: communication, micromanipulation, microscopy, among others. The production of OAM beams in the extreme ultraviolet (XUV) and X-ray regimes is of great interest as it allows to extend the applications of optical vortices down to the nanometric scale. Several proposals have been explored in order to generate XUV vortices in synchrotrons and FEL facilities. Here, we study the generation of XUV vortices through high-order harmonic generation (HHG). HHG is a unique source of coherent radiation extending from the XUV to the soft X-ray regime, emitted in the form of attosecond pulses. When driving HHG by OAM beams, highly charged XUV vortices with unprecedented spatiotemporal properties are emitted in the form of helical attosecond beams. In this chapter, we revise our theoretical work in the generation of XUV vortices by HHG. In particular, we illustrate in detail the role of macroscopic phase matching of high-order harmonics when driven by OAM beams, which allows to control the production of attosecond beams carrying OAM.
关键词： attosecond helical beams,ultrafast phenomena,orbital angular momentum,attosecond pulses,extreme ultraviolet vortices,high harmonic generation,nonlinear optics,phase matching
更新于2025-09-09 09:28:46
-
Vortex Dynamics and Optical Vortices || Optical Vortices Illumination Enables the Creation of Chiral Nanostructures
摘要： We discovered that optical vortices with an annular spatial form and an orbital angular momentum owing to a helical wave front enable us to twist materials, such as metal, silicon and azo-polymer, to form various structured matters including microneedles, chiral nanostructures and chiral surface reliefs. Such structured matters will potentially open the door to advanced devices, for instance, silicon photonic device, biomedical micro-electro-mechanical systems, ultrasensitive detector for chiral chemical composites and plasmonic metasurfaces for chiral chemical reactions.
关键词： chiral structured materials,singular optics,orbital angular momentum,laser materials processing,optical vortices
更新于2025-09-09 09:28:46
-
An Electronically Mode Reconfigurable Orbital Angular Momentum Array Antenna
摘要： In this paper, an array antenna for generating multi-mode orbital angular momentum (OAM) vortex waves and having electrically controlled mode reconfigurable function is proposed. The proposed antenna is based on a reconfigurable feed network (RFN) consisting of multiple PIN diodes as reconfigurable switches, a direct current (dc) control board and a 2 × 4 radial uniform circular array. By controlling the coding sequence of the corresponding PIN diode dc bias voltage on the RFN using a programmable microcontroller, the OAM modes generated by the proposed antenna can be dynamically reconfigured between l = 0, ±1, and ±2. Moreover, the OAM beams can be generated in a wide frequency band of 5.5–6.1 GHz and 5.65–6.1GHz for l = ± 1, ±2 modes and l = 0 mode, respectively. The prototype of the proposed antenna is simulated and fabricated to validate the proposed design. Both far-field and near-field experiments were performed to verify the feasibility of the proposed design. The results of the numerical simulation and measurement have good agreement with each other.
关键词： orbital angular momentum (OAM),array antenna,Reconfigurable,PIN diodes
更新于2025-09-09 09:28:46
-
Mapping Twisted Light into and out of a Photonic Chip
摘要： Twisted light carrying orbital angular momentum (OAM) provides an additional degree of freedom for modern optics and an emerging resource for both classical and quantum information technologies. Its inherently infinite dimensions can potentially be exploited by using mode multiplexing to enhance data capacity for sustaining the unprecedented growth in big data and internet traffic and can be encoded to build large-scale quantum computing machines in high-dimensional Hilbert space. While the emission of twisted light from the surface of integrated devices to free space has been widely investigated, the transmission and processing inside a photonic chip remain to be addressed. Here, we present the first laser-direct-written waveguide being capable of supporting OAM modes and experimentally demonstrate a faithful mapping of twisted light into and out of a photonic chip. The states OAM0, OAM?1, OAMt1, and their superpositions can transmit through the photonic chip with a total efficiency up to 60% with minimal crosstalk. In addition, we present the transmission of quantum twisted light states of single photons and measure the output states with single-photon imaging. Our results may add OAM as a new degree of freedom to be transmitted and manipulated in a photonic chip for high-capacity communication and high-dimensional quantum information processing.
关键词： Photonic chip,Twisted light,Quantum information processing,Orbital angular momentum
更新于2025-09-09 09:28:46
-
Atmospheric turbulence mitigation using spatial mode multiplexing and modified pulse position modulation in hybrid RF/FSO orbital-angular-momentum multiplexed based on MIMO wireless communications system
摘要： In this paper, the capacity of a free-space optical (FSO) communication over radio frequency (RF) could potentially be increased by the simultaneous transmission of multiple orbital angular momentum (OAM) based on spatial mode multiplexing (SMM) as an additional effective degree of freedom (EDOF) and quadrature amplitude modulation (QAM). This paper describes using hybrid RF/FSO-OAM based on multiple-input multiple-output (MIMO)/SMM using M-ary modified pulse position modulation (MPPM) and spatial PPM (SPPM) for potentially enhancing capacity in wireless communication systems. We present an analytical system design concerning OAM multiplexing and MIMO/SMM processing in free space communications channel under atmospheric turbulence (AT). Here, we assume a new architecture that closes the gap in speeds between millimeter-wave (mm-wave) wireless and optical links. In this study, we highlight recent advances in the use of OAM multiplexing for high-capacity FSO and mm-wave communications. We have developed the MPPM in FSO communication over RF using the source Gaussian model and SMM by proposing a new version of hybrid SPPM and MPPM. The novelty approach presents performance enhancement of the acquisition, pointing, tracking position and AT mitigation of link. We propose to use SMM combined with OAM-QAM based MIMO communications system to mitigate both weak and strong turbulence distortions. Simulation results show that the capacity of OAM-based MIMO system outperforms the capacity of the conventional MIMO system when the propagation distance is larger than a specific threshold. The use of transmitter lenses could enhance the OAM beams with a larger mode spacing (MS) of 2 (OAM l +1, l +3, l +5, l +7 transmitted) shows a lower power penalty (PP) when the inter-channel crosstalk overwhelms a larger lateral displacement of about 2 mm. Using the lenses at the transmitter to focus OAM beams could reduce power loss and PP in OAM-based FSO links and that this improvement might be more significant for higher-order OAM beams and provide high power-efficiency. With a larger of the transmitter and receiver 8 cm, 10 cm aperture size respectively, the system with mode spacing of 2 (OAM l +1, l +3, l +5, l +7 transmitted) and mode spacing of 3 (OAM l +1, l +4, l +7, l +10 transmitted) of OAM beams based on MIMO should fulfill lower-power penalty of 2.2 dB, 3.4 dB, as respectively and could enhance system robustness under angular error but degrade tolerance of lateral displacement. The proposed system provides an excellent signal-to-noise ratio (SNR) for the capacity in the regime of strong atmospheric turbulence. In this way, the maximization of FSO communication and RF wide, the data capacity enhancement, and it is considered a massive solution in the bandwidth provision for future access networks. This work could be beneficial to the practical implementation of OAM-MIMO/SMM multiplexed RF/FSO links.
关键词： Multiple-input multiple-output,Spatial mode multiplexing,Orbital angular momentum,Free space optical communications,Millimeter-wave communications,Modified pulse position modulation
更新于2025-09-04 15:30:14
-
[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Generation of Broadband Multiple OAM Modes Using Pancharatnam-Berry Metasurface
摘要： Vortex beams carrying orbital angular momentum (OAM) have been extensively realized using different approaches. Here, we present a Pancharatnam-Berry (PB) metasurface to generate broadband multiple vortex beams, which can carry different OAM modes towards different directions. The proposed PB metasurface could control the circularly polarized incident waves by attaching geometric phase to the orientation angle of the anisotropic meta-atoms. This design is numerically demonstrated at Ku band (12-18 GHz) and can be further exploited for OAM multiplexing in the communication systems.
关键词： vortex beam,Pancharatnam-Berry (PB) phase,Metasurface,orbital angular momentum (OAM)
更新于2025-09-04 15:30:14
-
[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Polarization-Dependent Full-Space Beam Steering with Orbital-Angular-Momentum Mode by Anisotropic Coding Metasurface
摘要： Coding metasurfaces have attracted much attention in recent years. Here, we propose a novel polarization-dependent full-space beam-steering anisotropic coding metasurface to radiate beams with orbital-angular-momentum (OAM) modes. When the polarizations of incident electromagnetic waves are orthogonal, the beams can be emitted to the upper and lower half spaces with different coding information, respectively. A scheme is presented to radiate multiple OAM modes with different deflecting angles to the corresponding spaces. This work has great potentials in multi-target communications and tracking radar systems.
关键词： coding metasurfaces,orbital-angular-momentum (OAM),multi-target communications,polarization-dependent,beam-steering,tracking radar systems
更新于2025-09-04 15:30:14
-
Automultiscopic displays based on orbital angular momentum of light
摘要： Orbital angular momentum (OAM) of light has drawn increasing attention due to its intriguingly rich physics and potential for a variety of applications. Having an unbounded set of orthogonal states, OAM has been used to enhance the channel capacity of data transmission. We propose and demonstrate the viability of using OAM to create an automultiscopic 3D display. Multi-view image information is encoded using an OAM beam array, then sorted into different view directions using coordinate transformation elements. A three-view demonstration was achieved to encode and decode 9 × 9 pixel images. These demonstrations suggest that OAM could potentially serve as an additional platform for future 3D display systems.
关键词： orbital angular momentum,automultiscopic 3D,display
更新于2025-09-04 15:30:14
-
A Reflectarray for Generating Wideband Circularly Polarized Orbital Angular Momentum Vortex Wave
摘要： A reflectarray for generating wideband circularly polarized (CP) orbital angular momentum (OAM) vortex wave in X band is proposed. First, a dual-linearly-polarized element consisting of two rhombus-shaped metal patches etched on two dielectric substrates is designed. The element has high isolations between two polarizations and preferable linear phase responses in wide frequency band. Then, the phase distribution of the reflectarray carrying the OAM vortex wave with mode l=1 is designed, and dimensions of the elements are determined by their reflective phases. The far-field radiation patterns and near-field phase distributions are simulated to verify the proposed design. Finally, prototype of a 313-element reflectarray with a linearly polarized (LP) Vivaldi feed, which converts an incident LP wave into a reflective CP wave, is fabricated and measured. The results of measurement indicate that the reflectarray can generate CP OAM vortex wave with mode l=1 in 9-11 GHz band (a fractional bandwidth of 20%). The reflectarray also achieves 20% 1-dB gain bandwidth, and its peak gain is 19.9 dB at 11 GHz. Except for a very narrow band (10.9-11.1 GHz), its measured 3-dB axial ratio (AR) bandwidth is about 40%.
关键词： reflectarray,Wideband,orbital angular momentum,circular polarization
更新于2025-09-04 15:30:14
-
Multiplexed OAM Wave Communication with Two-OAM-Mode Antenna Systems
摘要： In order to improve channel capacity, waves carrying orbital angular momentum (OAM) in communication systems have attracted much attention. A two-OAM-mode antenna system, which works at 2.4 GHz, is proposed in this paper. And a signal transmission experiment is performed based on a pair of the proposed antenna systems. The proposed antenna system, which has the planar structure, is composed of two patch antenna arrays, two feeding networks and one common ground plane. Then, re?ection coef?cients, transmission coef?cients, radiation patterns and phase distributions of the proposed antenna system are measured and the measurement results verify the effectiveness of this antenna system in generating two OAM modes (OAM mode 1 and OAM mode 2). The measurement results are in good agreement with the simulation results. Then the signal transmission system is built based on a pair of the proposed antenna systems. Isolation between OAM mode 1 transceiver channel and OAM mode 2 transceiver channel is more than 20 dB. Video signals modulated by FBMC (Filter Bank Multicarrier) are de-modulated simultaneously at the receiving terminal. It means that the two-OAM-mode antenna system has the potential to enhance the channel capacity.
关键词： antenna array,FBMC,Orbital angular momentum (OAM),patch antenna
更新于2025-09-04 15:30:14