Article
Optics
Yongguang Zhao, Li Wang, Weidong Chen, Pavel Loiko, Xavier Mateos, Xiaodong Xu, Ying Liu, Deyuan Shen, Zhengping Wang, Xinguang Xu, Uwe Griebner, Valentin Petrov
Summary: This study successfully generates ultrashort-pulse Hermite- and Laguerre-Gaussian laser modes with a pulse duration of around 100 fs from a compact solid-state laser in combination with a simple single-cylindrical-lens converter, pushing the advancement of such femtosecond structured laser sources into the 2-mu m spectral region. The negligible beam astigmatism, broad optical spectra, and almost chirp-free pulses highlight the high reliability of this laser source.
PHOTONICS RESEARCH
(2021)
Article
Optics
Mottamchetty Venkatesh, Rashid A. Ganeev, Vyacheslav V. Kim, Ganjaboy S. Boltaev, Ibrokhim B. Sapaev, Jingguang Liang, Jiaqi Yu, Wei Li
Summary: Intense high-order harmonics can be generated by phase- and polarization-structured femtosecond pulses. The strength of low-order harmonics varies with different driving beams (radially polarized beam, azimuthally polarized beam, and their superposition) in laser-induced plasmas. The phenomenon can be explained by phase matching and specific properties of vector beams.
Article
Physics, Multidisciplinary
Vivek Unikandanunni, Rajasekhar Medapalli, Marco Asa, Edoardo Albisetti, Daniela Petti, Riccardo Bertacco, Eric E. Fullerton, Stefano Bonetti
Summary: We investigate the spin dynamics driven by terahertz magnetic fields in epitaxial thin films of cobalt in its three crystalline phases. The angular momentum relaxation time is found to be the only material parameter needed to describe all the experimental evidence. Our experiments suggest a proportionality between the angular momentum relaxation time and the strength of the magnetocrystalline anisotropy.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Lang Li, Yingchi Guo, Zhichao Zhang, Zijun Shang, Chen Li, Jiaqi Wang, Liliang Gao, Lan Hai, Chunqing Gao, Shiyao Fu
Summary: Total angular momentum (TAM) of photons, which consists of spin angular momentum and orbital angular momentum, is an inherent degree of freedom and has attracted significant attention and interest in recent years. This paper proposes a TAM processor that enables tunable TAM manipulation through a set of quasi-symmetric units. Experimental results demonstrate the feasibility of the concept using 42 single TAM states, showing promising TAM state selection performance for applications such as high-speed large-capacity data transmission, optical computing, and high-security photon encryption systems.
ADVANCED PHOTONICS
(2023)
Article
Materials Science, Multidisciplinary
G. Stegmann, W. Toews, G. M. Pastor
Summary: This study presents an electronic theory of laser-induced ultrafast magnetization dynamics in transition-metal alloys. A many-body model Hamiltonian is used to incorporate electronic hopping, local Coulomb interaction, and spin-orbit coupling (SOC). Time propagations are performed on a tetrahedral cluster to obtain the time dependencies of local spin moments, orbital occupations, and single-particle energies for homogeneous systems and binary alloys. The effects of laser absorption inhomogeneities and SOC strengths on spin-density transfers between alloy components are investigated. A local perspective on optically induced spin transfer is proposed, involving dominantly local optical excitation followed by hopping-driven spin-density transfers among different alloy components. The role of electron delocalization and electronic hopping in spin-density redistribution and demagnetization of alloy components is demonstrated.
Article
Multidisciplinary Sciences
I. R. Khairulin, V. A. Antonov, M. Yu Ryabikin, M. A. Berrill, V. N. Shlyaptsev, J. J. Rocca, Olga Kocharovskaya
Summary: This work demonstrates how the challenges of amplifying attosecond pulses and producing a well-defined polarization state can be addressed simultaneously using a plasma-based X-ray amplifier modulated by an infrared field.
SCIENTIFIC REPORTS
(2022)
Article
Optics
Shuoshuo Zhang, Zhangyu Zhou, Yanan Fu, Qian Chen, Weipeng Li, Hui Fang, Changjun Min, Yuquan Zhang, Xiaocong Yuan
Summary: Spin and orbital angular momenta are essential physical quantities that describe optical fields' complex dynamic behaviors. The strong coupling between them gives rise to various intriguing topological phenomena, such as helicity-dependent optical vortex generation that converts spin to orbital degrees of freedom. However, current research mainly neglects the temporal properties of monochromatic optical fields. In this work, we demonstrate the temporal evolution of spin-to-orbit conversion induced by tightly-focused femtosecond optical fields, revealing a time-dependent conversion in polychromatic focused fields.
Review
Chemistry, Physical
Takashige Omatsu, Katsuhiko Miyamoto, Ken-Ichi Yuyama, Keisaku Yamane, Ryuji Morita
Summary: Helical light fields carrying orbital and spin angular momentum have the unique ability to twist materials and form exotic structures by interacting with them. This light-matter interaction has the potential to revolutionize industrial processes, including non-contact printing, and enable the production of advanced photonics, electronics, and spintronics devices. This review focuses on the printing technique called optical vortex laser induced forward transfer and discusses the interactions between light's angular momentum and materials, as well as the fabrication of novel devices using this technique.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS
(2022)
Article
Chemistry, Multidisciplinary
Yang Liu, Yuchi Huo, Lin Zhu, Mingxing Jin, He Zhang, Suyu Li, Wei Hua, John Xiupu Zhang
Summary: This study experimentally investigates the conical emission induced by femtosecond vortex beams in water. The characteristics of the conical emission induced by two types of vortex beams are studied by recording the light spots of different spectra components. The study also discusses the transfer of optical angular momentum during the supercontinuum induced by the filamentation of femtosecond vortex beams.
APPLIED SCIENCES-BASEL
(2023)
Article
Physics, Multidisciplinary
Hong -Bin Yao, Qi-Wen Qu, Zhao-Han Zhang, Jia-Wei Wang, Jian Gao, Chen-Xi Hu, Hui Li, Jian Wu, Feng He
Summary: Ionization reduction of atoms in two-color femtosecond laser fields is investigated in this study, combining theoretical and experimental approaches. The ionization probability of atoms undergoing multiphoton ionization with a 400 nm laser pulse is found to be reduced when overlapped with a relatively weak 800 nm laser pulse. This ionization reduction phenomenon is consistently observed regardless of the relative phase between the two pulses. Simulation results based on the time-dependent Schrodinger equation demonstrate that assisted by the 800 nm photons, electrons can be propelled into Rydberg states with large angular quantum numbers, which are spatially separated from the nuclei and less likely to be liberated in the multiphoton regime. This mechanism is applicable to hydrogen, helium, and potentially other atoms with properly tuned two-color laser fields.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
David R. Blackman, Yin Shi, Sallee R. Klein, Mihail Cernaianu, Domenico Doria, Petru Ghenuche, Alexey Arefiev
Summary: This study investigates an alternative electron injection method using a low-density foam target and a helical laser pulse. Three-dimensional simulations demonstrate that this method can generate a high-energy, short acceleration distance, and low-divergence electron beam.
COMMUNICATIONS PHYSICS
(2022)
Article
Physics, Multidisciplinary
Iman Ahmadabadi, Hossein Dehghani, Mohammad Hafezi
Summary: Motivated by recent experimental demonstrations of Floquet topological insulators, theoretical proposals have investigated the use of structured light to create additional properties like flat bands and vortex states. This study examines the effects of light's orbital angular momentum, revealing non-zero orbital magnetization and current density. The authors also investigate the optical conductivity for diverse electron transitions within the system, including vortex, edge, and bulk states.
COMMUNICATIONS PHYSICS
(2023)
Article
Optics
Guan Gui, Nathan J. Brooks, Henry C. Kapteyn, Margaret M. Murnane, Chen-Ting Liao
Summary: The study observes the second-harmonic spatiotemporal orbital angular momentum of an optical pulse and reveals the conservation of topological charge during frequency doubling. The experiment suggests a general nonlinear scaling rule for ST-OAM, analogous to conventional OAM of light, and demonstrates that the topology of a second-harmonic ST-OAM pulse can be modified by complex spatiotemporal astigmatism.
Article
Optics
Zijun Peng, Qing Wang, Hongshan Chen, Hongyu Liu, Xin Liu, Lison Yan, Jinwei Zhang
Summary: We have successfully generated high-order transverse modes from a Kerr-lens mode-locked femtosecond laser by non-collinear pumping. The generated modes were converted into Laguerre-Gaussian vortex modes using a cylindrical lens mode converter. This work demonstrates the potential of developing Kerr-lens mode-locked bulk lasers with various pure high-order modes and opens up possibilities for generating ultrashort vortex beams.
Article
Multidisciplinary Sciences
Tiancheng Huo, Li Qi, Jason J. Chen, Yusi Miao, Zhongping Chen
Summary: This study presents a femtosecond pulse scope that unifies vector vortex mode-locked lasing and vectorial quantification. By implementing intracavity-controlled phase modulation, continuous and ergodic generation of spirally polarized states along a broadband higher-order Poincare sphere was achieved. The proposed methodology opens up possibilities for optimizing ultrafast optics and facilitating applications in optical physics research and laser-based manufacturing.
SCIENTIFIC REPORTS
(2021)