Author Affiliations
Abstract
1 School of Physics and Optoelectronics, State Key Laboratory of Luminescent Materials and Devices, Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
2 Research Institute of Future Technology, South China Normal University, Guangzhou, China
In this work, we present a high-power, high-repetition-rate, all-fiber femtosecond laser system operating at 1.5 $\unicode{x3bc}$ m. This all-fiber laser system can deliver femtosecond pulses at a fundamental repetition rate of 10.6 GHz with an average output power of 106.4 W – the highest average power reported so far from an all-fiber femtosecond laser at 1.5 $\unicode{x3bc}$ m, to the best of our knowledge. By utilizing the soliton-effect-based pulse compression effect with optimized pre-chirping dispersion, the amplified pulses are compressed to 239 fs in an all-fiber configuration. Empowered by such a high-power ultrafast fiber laser system, we further explore the nonlinear interaction among transverse modes LP01, LP11 and LP21 that are expected to potentially exist in fiber laser systems using large-mode-area fibers. The intermodal modulational instability is theoretically investigated and subsequently identified in our experiments. Such a high-power all-fiber ultrafast laser without bulky free-space optics is anticipated to be a promising laser source for applications that specifically require compact and robust operation.
high-power femtosecond fiber laser high repetition rate intermodal modulational instability nonlinear pulse compression High Power Laser Science and Engineering
2023, 11(4): 04000e50
Author Affiliations
Abstract
1 Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Laboratory of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
2 e-mail: caiyin@xjtu.edu.cn
Optical skyrmions formed by photonic spin–orbit (SO) coupling are of significant interest in high-dimensional optical information processing. We report the formation mechanism and non-Hermitian properties of skyrmion-like states in a circular confinement potential with photonic SO coupling, which is preferably realized in a concave-planar microcavity system. We show that the effective photonic gauge field leads to two split manifolds of degenerate skyrmions whose spin textures can be controlled via the non-Hermitian properties by introducing circularly polarized gain and loss, exhibiting dramatically discrepant evolutions at the two sides of the exceptional point (EP). Furthermore, the lifetime degeneracy can be lifted by spatially inhomogeneous pumping according to the non-Hermitian mechanism, enabling the possibility for the skyrmion laser. By introducing shape asymmetry of the confinement potential, a double EP evolution can be achieved, which allows non-Hermitian control of the SO coupled states with higher degrees of freedom. These results open the way for the non-Hermitian control of photonic spin in confined systems, which would be of great significance for the fundamentals of advanced optical information processing.
Photonics Research
2023, 11(4): 610
1 高性能土木工程材料国家重点实验室, 南京 211103
2 江苏苏博特新材料股份有限公司, 南京 211103
3 东南大学材料科学与工程学院, 南京 211189
为提升粗骨料超高性能混凝土(CA-UHPC)的流变与物相稳定性能, 研究了硅灰、粗骨料和纤维用量对CA-UHPC流变性能的影响规律; 建立了流变参数、纤维、骨料分布间的关系。结果表明: CA-UHPC呈剪切变稀行为, Modified bingham模型具有更准确的流变参数拟合结果, 测试流动度宜控制在450~690 mm。增加硅灰用量, 屈服应力增大而黏度减小, 剪切变稀现象弱化; 增加粗骨料用量, 屈服应力和黏度先降低后增加, 剪切变稀现象加剧; 增加钢纤维掺量, 屈服应力和黏度均增加, 并加剧了剪切变稀现象。硬化后试件从上至下, 纤维分布减少, 而骨料分布增多。粗骨料的整体均匀分散程度随骨料用量的增加而提升, 但纤维会劣化粗骨料的均匀分散程度, 且随纤维掺量增加, 纤维和粗骨料均匀分布程度先升高后降低。
粗骨料超高性能混凝土 流变性能 粗骨料分布 钢纤维分布 稳定性 ultra-high performance concrete containing coarse rheological properties coarse aggregate distribution steel fiber distribution stability
Author Affiliations
Abstract
1 Zhejiang Engineering Research Center for Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Scienceshttps://ror.org/034t30j35, Ningbo 315201, China
2 Yongjiang Laboratory, Ningbo 315201, China
3 Advanced Micro-Fabrication Equipment Inc., Shanghai 201201, China
4 Department of Physics, Xiamen University, Xiamen 361005, China
5 University of Chinese Academy of Sciences, Beijing 100049, China
6 e-mail: jichun.ye@nimte.ac.cn
Semipolar III-nitrides have attracted increasing attention in applications of optoelectronic devices due to the much reduced polarization field. A high-quality semipolar AlN template is the building block of semipolar AlGaN-based deep-ultraviolet light emitting diodes (DUV LEDs), and thus deserves special attention. In this work, a multi-step in situ interface modification technique is developed for the first time, to our knowledge, to achieve high-quality semipolar AlN templates. The stacking faults were efficiently blocked due to the modification of atomic configurations at the related interfaces. Coherently regrown AlGaN layers were obtained on the in situ treated AlN template, and stacking faults were eliminated in the post-grown AlGaN layers. The strains between AlGaN layers were relaxed through a dislocation glide in the basal plane and misfit dislocations at the heterointerfaces. In contrast, high-temperature ex situ annealing shows great improvement in defect annihilation, yet suffers from severe lattice distortion with strong compressive strain in the AlN template, which is unfavorable to the post-grown AlGaN layers. The strong enhancement of luminous intensity is achieved in in situ treated AlGaN DUV LEDs. The in situ interface modification technique proposed in this work is proven to be an efficient method for the preparation of high-quality semipolar AlN, showing great potential towards the realization of high-efficiency optoelectronic devices.
Photonics Research
2022, 10(12): 2778
1 南开大学 电子信息与光学工程学院, 天津 300350
2 南开大学 现代光学研究所, 天津 300350
3 南方海洋科学与工程广东省实验室(珠海), 广东 珠海 519000
为提高多口径发射的自由空间光通信系统性能, 以“海洋高速通信网络关键技术研究与验证”项目为背景, 提出了平均误码率(BER)的解析表达式。通信系统采用典型的强度调制直接探测(IMDD), 工作在由指数威布尔(EW)分布模型描述的湍流环境中。分析了系统在不同信道参数下的孔径平均效应, 以及不同发射口径数和通信速率对平均BER的影响。仿真结果表明: 低通信速率下多口径发射系统具有良好的湍流抑制能力, 高通信速率下不同发射口径的到达时间差会增加通信系统的误码概率。
自由空间光通信 大气湍流 多口径发射 指数威布尔分布模型 free space optical communication, turbulent atmosp
激光与光电子学进展
2022, 59(22): 2210009
中国激光
2021, 48(24): 2404003
Author Affiliations
Abstract
Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
In inertial confinement fusion experiments, fuel quality is determined mainly by the thermal environment of the capsule in the layering procedure. Owing to the absence of a radial thermal gradient, formed deuterium–deuterium (DD) ice shells in the capsule are thermally instable. To obtain a solid DD layer with good quality and long lifetime, stringent demands must be placed on the thermal performance of cryogenic targets. In DD cryogenic target preparation, two issues arise, even after the capsule’s temperature uniformity has been improved by the use of thick aluminized films. The first is the inconsistent ice shape, which is related to the capsule’s thermal field. In this article, some typical fabrication details are investigated, including adhesive penetration during assembly, the presence of the fill tube, the optical properties of the hohlraum and film surfaces, the jacket–hohlraum connection, deviations in capsule location, and asymmetrical contact at the arm–jacket interfaces. Detailed comparisons of the thermal effects of these factors provide guidance for target optimization. The second issue is the instability of seeding crystals in the fill tube due to unsteadiness of the direction of the thermal gradient in the fill tube assembly. An additional thermal controller is proposed, analyzed, and optimized to provide robust controllability of tube temperature. The analysis results and optimization methods presented in this article should not only help in dealing with thermal issues associated with DD cryogenic targets, but also provide important references for engineering design of other cryogenic targets.
Matter and Radiation at Extremes
2021, 6(5): 055901
Author Affiliations
Abstract
1 Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Institute of Modern Optics, Nankai University, Tianjin 300350, China
2 Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, College of Electronic and Information Engineering, Tianjin Polytechnic University, Tianjin 300387, China
A 473-nm-laser-tuned whispering gallery mode (WGM) silica microbubble resonator integrated with iron oxide particles is demonstrated in this paper. Owing to the photo-induced thermal effect, the WGM resonance wavelength could be tuned by adjusting laser power density of the illuminating light absorbed by the iron oxide particles. A wavelength tuning sensitivity of 0.03 nm/(mW·mm-2) and a tuning range of 0.18 nm are experimentally achieved. Moreover, the influence of ambient temperature on the WGM spectral characteristics is experimentally studied, and a silica- microbubble-based reference scheme is demonstrated to compensate for the temperature-caused resonance wavelength variation. The proposed laser-tuned microresonator has great potential in optical modulation and high-precision optical filtering applications.
光电子快报（英文版）
2021, 17(3): 129
Author Affiliations
Abstract
1 Beijing Institute of Remote Sensing Equipment, Beijing 100039, China
2 Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Institute of Modern Optics, Nankai University, Tianjin 300350,China
3 Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519000, China
Laser communication is essential part of maritime-terrestrial-air intelligent communication/sensor network. Among them, different modulation formats would play a unique role in specific applications. Based on Rytov theory, we discussed system performance of the maritime laser communication with repeated coding technology in several modulation schemes. The closed-form expression of average bit error rate (BER) from weak to moderate atmospheric turbulence described by log-normal distribution is given. Differential phase shift keying (DPSK) modulation, as a potential solution for future maritime laser communication, has attracted a lot of attention. We analyzed the effects of atmospheric turbulence parameters (visibility, refractive index structure coefficient, non-Kolmogorov spectral power-law exponent, turbulence inner scale) and DPSK system parameters (receiver aperture diameter, repeat time) on average BER in detail. Compared with the aperture-averaging effects, the system BER can be well suppressed through increasing repeat time. This work is anticipated to provide a theoretical reference for maritime laser communication systems.
光电子快报（英文版）
2021, 17(2): 90
