Author Affiliations
Abstract
1 Tsung-Dao lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
2 Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
3 Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China
4 Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG, UK
Terahertz radiation with a Bessel beam profile is demonstrated experimentally from a two-color laser filament in air, which is induced by tailored femtosecond laser pulses with an axicon. The temporal and spatial distributions of Bessel rings of the terahertz radiation are retrieved after being collected in the far field. A theoretical model is proposed, which suggests that such Bessel terahertz pulses are produced due to the combined effects of the inhomogeneous superluminal filament structure and the phase change of the two-color laser components inside the plasma channel. These two effects lead to wavefront crossover and constructive/destructive interference of terahertz radiation from different plasma sources along the laser filament, respectively. Compared with other methods, our technique can support the generation of Bessel pulses with broad spectral bandwidth. Such Bessel pulses can propagate to the far field without significant spatial spreading, which shall provide new opportunities for terahertz applications.
Ultrafast Science
2022, 2(1): 9870325
重庆邮电大学 自主导航与微系统重庆市重点实验室, 重庆 400065
针对车体振动影响微机电系统惯性测量单元(MEMS IMU)航向精度问题, 提出了一种能有效抑制振动噪声从而提升航向精度与稳定性的方法。首先, 采用最小均方法对数据进行前端预处理, 以提升信噪比; 然后, 利用加速度计与陀螺仪的互补特性滤除陀螺仪的零偏噪声; 最后, 采用扩展卡尔曼滤波进一步滤波。总计4h的现场实验结果表明: IMU受载体振动影响较小, 航向的精度与稳定性得到提升; 其中, 在大角度机械运动后的相对航向误差为3.08°, 静止时的航向方差为2.44×10-5。
Author Affiliations
Abstract
1 Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
2 Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China
A probe-shaped sensor for simultaneous temperature and pressure measurement was reported in this article. The effective length of the sensor was ~2 mm, consisting of a fiber Bragg grating (FBG) and a Fabry-Perot interferometer (FPI) with a nano silica diaphragm. The response sensitivities of the sensor for pressure and temperature were measured as –0.98 nm/MPa and 11.10 pm/℃, respectively. This sensor had an extremely low cross-sensitivity between pressure and temperature, which provided a significant potential in dual-parameter sensing.
Fabry-Perot interferometer fiber Bragg grating fiber optics sensors Photonic Sensors
2021, 11(4): 411
Author Affiliations
Abstract
1 Center for Advanced Material Diagnostic Technology, College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, China
2 Shenzhen Key Laboratory of Laser Engineering, Shenzhen University, Shenzhen 518060, China
3 College of New Materials and New Energies, Shenzhen Technology University, Shenzhen 518118, China
4 Institute of Applied Physics & Materials Engineering, Faculty of Science and Technology, University of Macau, Macau, China
Carbon nanodots (C-dots) with a uniform size of about 2 nm are synthesized via in situ pyrolysis of n-propylamine that is confined in the nanochannels of zeolite Linde Type A (LTA). The as-synthesized C-dots@LTA composite shows nonlinear optical saturable absorption properties in a broad wavelength band and can be used as saturable absorber (SA) to generate ultrafast pulsed fiber lasers. By inserting a zeolite LTA single crystal hosting C-dots into the fiber laser cavity, mode-locked fiber lasers with long-term operation stability at 1.5 μm and 1 μm are achieved. These results show that the C-dots@LTA are a promising SA material for ultrafast pulsed fiber laser generation in a broad wavelength band. To the best of our knowledge, this is the first demonstration of a C-dots@LTA-based mode-locked fiber laser.
Photonics Research
2019, 7(10): 10001182
Author Affiliations
Abstract
1 Shenzhen Key Laboratory of Laser Engineering, Key Laboratory of Advanced Optical Precision Manufacturing Technology of Guangdong Higher Education Institutes, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
2 Institute of Applied Physics and Materials Engineering, University of Macau, Macau, China
Employing 0.3 nm diameter single-walled carbon nanotubes (SWCNTs) as saturable absorbers, we demonstrate a passively mode-locked fiber laser operating at 1950 nm. The 0.3 nm diameter SWCNTs are prepared by pyrolyzing dipropylamine in the channels of zeolite crystals MgAPO-11 (AEL). The laser pumped by a 1550 nm laser source produces 972 fs pulses with a spectral width at half-maximum of 4.2 nm and a repetition rate of 21.05 MHz, an average output power of 2.3 mW corresponding to the maximum pump power of 420 mW with a 10% output coupler.
140.3510 Lasers, fiber 140.4050 Mode-locked lasers 160.4236 Nanomaterials Chinese Optics Letters
2017, 15(4): 041403
1 长沙理工大学化学与生物工程学院, 湖南 长沙 410000
2 国防科学技术大学光电科学与工程学院, 湖南 长沙 410073
3 国防科学技术大学理学院, 湖南 长沙 410073
生物激光打印(BioLP)能够将含生物材料的极微量溶液精确打印在不同的位置而不致生物活性受损，是一种新型的生物打印技术。介绍了生物激光打印技术的原理、设备及其关键处理技术，以及该技术近年来的研究进展，并对其未来发展和挑战进行了展望。
生物光学 生物激光打印 组织工程 微阵列 单细胞分离 激光与光电子学进展
2016, 53(4): 040001
上海交通大学物理与天文系激光等离子体教育部重点实验室, 上海 200240
强激光脉冲与气体靶作用是产生高功率太赫兹(THz)辐射的一个重要途径。利用光电离电流模型研究了同向传播的波长为0.8 mm 的激光及其半频光为1.6 mm 的激光与气体作用产生强太赫兹辐射的过程。讨论了气体种类、激光振幅、双色激光相位差对离化电流的影响。与通常的0.8 mm 激光及其倍频光组合相比，在同等激光强度下利用半频光组合可以产生更强的太赫兹辐射，约为倍频情况下的两倍。通过改变双色激光偏振方向的夹角，当两个光的偏振垂直时，即使半频光的强度远低于基频光，离化电流的方向也由半频光的偏振方向决定。
光谱学 太赫兹辐射 双色激光 离化电流模型 偏振夹角 激光与光电子学进展
2015, 52(7): 073001
Author Affiliations
Abstract
1 Department of Mechanical &
2 Electrical Engineering, Xiamen University, Xiamen 361005, China
3 Department of Orthopaedics, Xiamen University, Affiliated ZhongShan Hospital, Xiamen 361005, China
It is highly necessary to study the phenomenon of photon migration in the knee joint for the non-invasive near-infrared optical early diagnosis of the osteoarthritis of the knee. We investigate the migration trace and distribution rule of the photons in knee layered structure, which are simulated by the Monte-Carlo modeling. The proportion of photons which collide with bone tissue then migrate out of the muscle tissue and photons directly migrate out of muscle tissue is calculated. For analyzing the signal-to-noise ratio to determine the accurate position of the detector, we perform quantitative evaluations of distribution of photons, as well as qualitative assessments of the distribution of photons.
170.3660 Light propagation in tissues 170.5280 Photon migration 170.6930 Tissue Chinese Optics Letters
2014, 12(s2): S21701
上海交通大学激光与等离子体教育部重点实验室, 上海 200240
介绍了激光诱导击穿光谱(LIBS)技术的原理，重点讨论了该技术在液体样品方面的技术发展和应用，分析并比较了选取不同样品形式(液体内部、液体表面、液体喷流、液滴以及将液体转化为固体等)的优劣，指出提高元素检测限的关键。液体LIBS 技术因其可在线、快速检测等优点，在环境检测、污水处理、生物医药、工业控制等诸多方面具有巨大的应用潜力。
光谱学 激光诱导击穿光谱 液体 元素检测 激光与光电子学进展
2014, 51(10): 100001
Author Affiliations
Abstract
Broadband and energetic terahertz (THz) pulses can be remotely generated in air through filamentation. We review such THz generation and detection in femtosecond Ti-sapphire laser induced remote filaments. New results are presented on the direct relationship between THz generation in a two color filament and induced N2 fluorescence through population trapping during molecular alignment and revival in air. This further supports the new technique of remote THz detection in air through the sensitive measurement of N2 fluorescence.
140.3070 Infrared and far-infrared lasers 190.5530 Pulse propagation and temporal solitons 350.5400 Plasmas Chinese Optics Letters
2013, 11(1): 011401
