分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Relativistic vortex particles offer a promising avenue for investigating and manipulating processes in high-energy and nuclear physics, as they provide an additional degree of freedom in the form of orbital-angular-momentum (OAM). Despite the potential benefits, the generation and detection of these particles have proven to be a significant challenge. In this work, we present a new method for producing high-energy vortex electrons and $\gamma$-photons by colliding relativistic electrons with circularly polarized laser pulses in the radiation-dominated quantum electrodynamics (QED) regime. We use the laser-dressed vortex state to develop a nonlinear scattering theory, which allows us to understand the transfer of spin angular momenta (SAM) to intrinsic OAM in the highly nonlinear multi-photon process. The theory shows that electrons in the vortex state carry higher intrinsic OAM when radiation-reaction becomes significant, with the central OAM number proportional to the amount of energy taken by the $\gamma$-photon. This study provides an effective approach to generating high-energy vortex electron beams using laser intensities that are currently achievable. Additionally, the emission spectra of energetic electrons in vortex states are found to exhibit multi-peaks, which sets them apart from plane-wave electrons and makes them easier to distinguish.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Cheng Zhang
Tiandao Chen
Jinyu Pan
Zhiyuan Huang
Donghan Liu
Ding Wang
Fei Yu
Dakun Wu
Yu Zheng
Ruochen Yin
Xin Jiang
Meng Pang
Yuxin Leng
Ruxin Li
摘要： High-energy ultraviolet pulse generation in gas-filled hollow capillary fibers (HCFs) through dispersive-wave-emission process, has attracted considerable attentions in recent several years due to its great application potentials in ultraviolet spectroscopy and photochemistry. While the ability of this technique to deliver high-energy, ultrafast ultraviolet pulses is widely recognized, few-fs duration of {\mu}J-level dispersive-wave (DW) pulses has, however, escaped direct measurements. In this letter, we demonstrate that using several chirped mirrors, few-fs ultraviolet DW pulses can be obtained in atmosphere environment without the use of vacuum chambers. The pulse temporal profiles, measured using a self-diffraction frequency-resolved optical gating set-up, exhibit full-width-half-maximum pulse widths of 9.6 fs at 384 nm and 9.4 fs at 430 nm, close to the Fourier-transform limits. Moreover, theoretical and experimental studies reveal the strong influences of driving pulse energy and HCF length on temporal width and shape of the measured DW pulses. The ultraviolet pulses obtained in atmosphere environment with {\mu}J-level pulse energy, few-fs pulse width and broadband wavelength tunability are ready to be used in many applications.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The peak power improvement and running safety of petawatt (PW) lasers are limited by laser-induced damage of optical components with limited sizes and damage thresholds. Diffraction gratings in pulse compressors have been the shortest stave of PW lasers up to now, as to manufacture a high quality meter-sized grating remains particularly challenging. Here, the asymmetric four-grating compressor (AFGC) with asymmetric configuration is proposed for PW lasers to increase the maximum bearable output pulse energy and running safety without neither additional optical component nor extra control in comparison to a traditional Treacy four-grating compressor (TFGC) with symmetric configuration. In AFGC, suitable spatial dispersion can be introduced in the output laser beam which is able to decrease the laser spatial intensity modulation (LSIM) of the output beam on the final grating. The introduced spatial dispersion can be automatically compensated at the focal plane by using the spatiotemporal focusing technique. Based on this simple AFGC design, not only the damage risk of the final grating can be reduced, but also the maximum output pulse energy can be improved by about 1.8 times theoretically. As an example, 100 PW output power can be achieved theoretically by using the AFGC with an input beam size of 550*700 mm2.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： A multistage smoothing multistep pulse compressor (MPC) based on a single-pass single-grating-pair (SSGP) main compressor is proposed to simplify the entire petawatt (PW) compressor. Only one grating pair with relatively long distance is used to generate the same amount of spectral dispersion in the main compressor compared with a four-grating main compressor. As the SSGP induces the largest spatial dispersion, it can introduce the best beam-smoothing effect to the laser beam on the last grating. When considering the diffraction loss of only two gratings, the total compression efficiency of the SSGP main compressor is even larger than that of a four-grating main compressor. Furthermore, the spatiotemporal aberration induced by single-grating-pair can be compensated effectively by using deformable mirrors, however it is difficult or complicated to be well compensated in a four-grating compressor. Approximately 50-100 PW laser pulses can be obtained using this SSGP-based multistage smoothing MPC with a single laser beam
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Ultrahigh peak power lasers are important scientific tools for frontier laser-physics researches, in which both the peak power improvement and operating safety are very important meanwhile limited by the damage threshold and size of compression gratings currently. Based on a recent reported method "multistep pulse compressor (MPC)", a multistage smoothing based MPC (MS-MPC) is proposed here to further improve the running safety, operating convenience, and simplify the whole setup of the MPC. In this optimized design, the beam smoothing is not simply executed in the pre-compressor or main-compressor, but separated into multistage. Then, it can protect important optics in every stage directly and reduce the executing difficult of typical MPC at the same time. The prism pair based pre-compressor will induce suitable spatial dispersion which is easier to be achieved and enough to protect the first grating directly. At the same time, the asymmetric four-grating compressor (AFGC) will also induce spatial dispersion to further smooth the laser beam which helps to protect the last grating directly. In this way, 10s-100s PW lasers can be compressed by using current available optics with improved operating safety owing to remove random spatial intensity modulations. Furthermore, an additional beam smoothing stage can be added before the main amplifier to protect the biggest amplification crystal away from damage. This MS-MPC optical design can be easily extended to be used in all exist PW laser facilities to improve their potential compressed pulse energy and running safety.
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