Article
Optics
Hao Wang, Ziyu Zhan, Yijie Shen, Jianqi Hu, Xing Fu, Qiang Liu
Summary: In the face of a pending capacity crunch in the information era, researchers have demonstrated an alternative method to increase transmission bandwidth by utilizing multiple non-orthogonal states of structured light. This challenges the prevailing view of using orthogonal states as information carriers. Using an adapted deep neural network, six categories of beams were accurately recognized, providing the targeted wide bandwidth. The efficiency was further demonstrated through the transmission/reception of a grayscale image encoded using 256-ary mode encoding and shift keying schemes. The well-trained model also showed high fidelity recognition of structured beams under unknown turbulence and restricted receiver aperture size. This work holds significant potential for intelligence-assisted large-capacity and secure communications to meet the growing demand for daily information bandwidth.
Article
Nanoscience & Nanotechnology
Thomas Dinter, Chenhao Li, Lucca Kuehner, Thomas Weber, Andreas Tittl, Stefan A. Maier, Judith M. Dawes, Haoran Ren
Summary: This study demonstrates the use of an ultrathin OAM mode-sorting metasurface for characterizing the breakdown of OAM orthogonality under different turbulence conditions. The metasurface exhibits strong OAM selectivity and allows the measurement of the whole OAM spectrum at the same time.
Article
Multidisciplinary Sciences
Xiyuan Lu, Mingkang Wang, Feng Zhou, Mikkel Heuck, Wenqi Zhu, Vladimir A. Aksyuk, Dirk R. Englund, Kartik Srinivasan
Summary: The authors demonstrate a method for generating orbital angular momentum (OAM) using photonic crystal ring resonators, while maintaining high cavity quality factors (up to 10^6). By ejecting high angular momentum states of a whispering gallery mode (WGM) microresonator through a grating-assisted mechanism, a scalable and chip-integrated solution for OAM generation is achieved.
NATURE COMMUNICATIONS
(2023)
News Item
Optics
Spencer W. Jolly
Summary: A diffractive axicon can create intricate connections between topological charges and frequencies of ultrashort laser pulses, resulting in a diverse range of coiled light structures.
Article
Physics, Multidisciplinary
Yongtao Zhang, Jiayi Yu, Greg Gbur, Olga Korotkova
Summary: The behavior of orbital angular momentum (OAM) flux density of partially coherent vortex (PCV) beams in atmospheric turbulence was investigated. Different spatial coherence structures of PCV beams result in rich variations in OAM flux density distribution along the propagation path, providing insight into the use of OAM in free-space optical communications under significant turbulence effects.
FRONTIERS IN PHYSICS
(2022)
Article
Optics
Kai Pang, Kaiheng Zou, Hao Song, Zhe Zhao, Amir Minoofar, Runzhou Zhang, Haoqian Song, Huibin Zhou, Xinzhou Su, Cong Liu, Nanzhe Hu, Moshe Tur, Alan E. Willner
Summary: By coherently combining multiple frequencies, near-diffraction-free and near-dispersion-free OAM pulses with arbitrary group velocities have been generated. It has been found that both positive and negative group velocities can be achieved and continuously controlled, and that the simulated value of group velocity remains the same when the topological charge l is varied. However, as the l value increases, the pulse duration becomes longer for a given number of frequency lines.
Article
Multidisciplinary Sciences
Zelin Ma, Poul Kristensen, Siddharth Ramachandran
Summary: Spatial mode-count scalability in optical fibers is severely limited by perturbative mode mixing. We propose an alternative means of light guidance using light's orbital angular momentum to create a centrifugal barrier. This distinctive light-guidance regime enables low-loss transmission of light, substantially increasing the information content per photon for quantum or classical networks.
News Item
Optics
Philippe St-Jean
Summary: This paper presents a novel solid-state laser that can generate a large array of phase-locked optical vortices with tunable orbital angular momentum.
Article
Physics, Multidisciplinary
Asher Klug, Isaac Nape, Andrew Forbes
Summary: By calculating the orbital angular momentum (OAM) of the atmosphere itself, researchers have drawn general conclusions on the impact of atmospheric turbulence on OAM beams. These conclusions have been experimentally confirmed, opening up new insights into the physics of OAM in turbulence and can be extended to other structured light fields through arbitrary aberrations.
NEW JOURNAL OF PHYSICS
(2021)
Article
Optics
Jingjing Meng, Jianguo He, Min Huang, Yang LI, Baoyu Zhu, Xinxin Kong, Zhe Han, Xin LI, Yang Liu
Summary: This study proposes a deep learning method that combines CNN and ConvLSTM models to compensate for atmospheric turbulence and correct distorted beams. The experimental results show that this method can effectively and accurately compensate for distorted beams.
Editorial Material
Optics
Gianluca Ruffato
Summary: A recent publication suggests a solution to overcome the limitations of optical techniques and high-intensity beams by probing highly-intense vortex pulses with a structured reference beam.
LIGHT-SCIENCE & APPLICATIONS
(2022)
Article
Optics
Pauline Boucher, Hugo Defienne, Sylvain Gigan
Summary: This study demonstrates tunable control of spatial correlations between photon pairs in order to engineer the properties of quantum optical states, measured using an EMCCD camera. By shaping the spatial pump beam profile, the spatial structure of entangled photon pairs in high dimensions was tailored without affecting intensity, holding potential for quantum technologies based on high-dimensional spatial entanglement.
Article
Optics
Asher Klug, Cade Peters, Andrew Forbes
Summary: Structured light is commonly used in free-space optical communication channels to increase bandwidth by encoding information in the spatial structure. Turbulence in the atmosphere can cause distortions in structured light modes, leading to amplitude and phase distortions. We propose complex forms of structured light that are invariant under atmospheric turbulence and provide a theoretical procedure for obtaining these eigenmodes. The proposed approach can also be extended to other channels such as aberrated paths, underwater, and optical fiber.
ADVANCED PHOTONICS
(2023)
Article
Optics
Wenhua He, Saikat Guha, Jeffrey H. Shapiro, Boulat A. Bash
Summary: This paper theoretically analyzes spatial-mode-multiplexed, decoy-state BB84 quantum key distribution systems with transmitter modes being either a collection of phase-tilted, flat-top focused beams (FBs) or Laguerre-Gaussian (LG) modes. Despite the QKD rate penalty suffered by FBs relative to LG modes in vacuum propagation, their potential ease of implementation makes them an attractive alternative. Furthermore, in the presence of turbulence, FB modes may outperform LG modes.
Article
Chemistry, Analytical
Jian Yang, Yingning Wang, Yuxi Fang, Wenpu Geng, Wenqian Zhao, Changjing Bao, Yongxiong Ren, Zhi Wang, Yange Liu, Zhongqi Pan, Yang Yue
Summary: In this paper, a silica-cladded Germania-doped ring-core fiber (RCF) that supports orbital angular momentum (OAM) modes is designed. By optimizing the fiber structure parameters, the RCF achieves near-zero flat dispersion. This design serves as an efficient way to extend the spectral coverage of beams carrying OAM modes for various applications.
