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| 1 | Single-shot BOTDA based on an optical chirp chain probe wave for distributed ultrafast measurement显示文摘Brillouin optical time-domain analysis(BOTDA)requires frequency mapping of the Brillouin spectrum to obtain environmental information(e.g.,temperature or strain)over the length of the sensing fiber,with the finite frequencysweeping time-limiting applications to only static or slowly varying strain or temperature environments.To solve this problem,we propose the use of an optical chirp chain probe wave to remove the requirement of frequency sweeping for the Brillouin spectrum,which enables distributed ultrafast strain measurement with a single pump pulse.The optical chirp chain is generated using a frequency-agile technique via a fast-frequency-changing microwave,which covers a larger frequency range around the Stokes frequency relative to the pump wave,so that a distributed Brillouin gain spectrum along the fiber is realized.Dynamic strain measurements for periodic mechanical vibration,mechanical shock,and a switch event are demonstrated at sampling rates of 25 kHz,2.5 MHz and 6.25 MHz,respectively.To the best of our knowledge,this is the first demonstration of distributed Brillouin strain sensing with a wide-dynamic range at a sampling rate of up to the MHz level. | Dengwang Zhou Yongkang Dong Benzhang Wang Chao Pang Dexin Ba Hongying Zhang Zhiwei Lu Hui Li Xiaoyi Bao | 2018 | Light(Science & Applications)2018，7，1： | 11 |
| 2 | High-performance optical chirp chain BOTDA by using a pattern recognition algorithm and the differential pulse-width pair technique显示文摘Optical chirp chain Brillouin optical time-domain analysis(OCC-BOTDA) has the capabilities of fast measurement, high Brillouin threshold, and freedom from the nonlocal effect;at the same time, however, it also has problems introduced by transient stimulated Brillouin scattering. The influence of the transient interaction is reflected as the broadened asymmetric Brillouin spectrum, the ghost peak, and the frequency shift of the main peak. This introduces difficulty in computing the fiber Brillouin frequency shift with good measurement accuracy. Besides, the OCC modulation causes additional noise due to the uneven amplitude response for different frequency components. In this work, we propose a high-performance OCC-BOTDA using the principal component analysis(PCA) based pattern recognition algorithm and differential pulse-width pair(DPP) technique.After building the Brillouin spectrum database(i.e., all patterns), the fiber intrinsic Brillouin frequency shift can be recognized by the PCA algorithm from a nonstandard Brillouin spectrum profile, resulting in good measurement accuracy. Meanwhile, the DPP technique, subtracting between two Brillouin signals generated by two wide-width pump pulses, is utilized to reduce the OCC modulation noise and avoid the pulse self-phase modulation effect in long-range BOTDA sensing. In the experiment, a temperature measurement with 1.3 MHz measurement precision, 4 m spatial resolution, and 5 s measurement time is achieved over a 100 km single-mode fiber. | BENZHANG WANG BAOHUA FAN DENGWANG ZHOU CHAO PANG YUE LI DEXIN BA YONGKANG DONG | 2019 | Photonics Research2019，7，6： | 5 |
| 3 | Hundred-Joule-level,nanosecond-pulse Nd:glass laser system with high spatiotemporal beam quality显示文摘A 100-J-level Nd:glass laser system in nanosecond-scale pulse width has been constructed to perform as a standard source of high-fluence-laser science experiments. The laser system, operating with typical pulse durations of 3–5 ns and beam diameter 60 mm, employs a sequence of successive rod amplifiers to achieve 100-J-level energy at 1053 nm at3 ns. The frequency conversion can provide energy of 50-J level at 351 nm. In addition to the high stability of the energy output, the most valuable of the laser system is the high spatiotemporal beam quality of the output, which contains the uniform square pulse waveform, the uniform flat-top spatial fluence distribution and the uniform flat-top wavefront. | Sensen Li Yulei Wang Zhiwei Lu Lei Ding Yi Chen Pengyuan Du Dexin Ba Zhenxing Zheng Xin Wang Hang Yuan Chengyu Zhu Weiming He Dianyang Lin Yongkang Dong Dengwang Zhou Zhenxu Bai Zhaohong Liu Can Cui | 2016 | High Power Laser Science and Engineering2016，4，1： | 3 |
| 4 | Non-destructive and distributed measurement of optical fiber diameter with nanometer resolution based on coherent forward stimulated Brillouin scattering显示文摘Precise control and measurement of the optical fiber diameter are vital for a range of fields,such as ultra-high sensitivity sensing and high-speed optical communication.Nowadays,the measurement of fiber diameter relies on point measurement schemes such as microscopes,which suffer from a tradeoff between the resolution and field of view.Handling the fiber can irreversibly damage the fiber samples,especially when multi-point measurements are required.To overcome these problems,we have explored a novel technique in which the mechanical properties of fibers are reflected by forward stimulated Brillouin scattering(FSBS),from which the diameters can be demodulated via the acoustic dispersion relation.The distributed FSBS spectra with narrow linewidths were recorded via the optimized optomechanical time-domain analysis system using coherent FSBS,thereby achieving a spatial resolution of 1 m over a fiber length of tens of meters.We successfully obtained the diameter distribution of unjacketed test fibers with diameters of 125μm and 80μm.The diameter accuracy was verified by high-quality scanning electron microscope images.We achieved a diameter resolution of 3.9 nm,virtually independent of the diameter range.To the best of our knowledge,this is the first demonstration of non-destructive and distributed fiber diameter monitoring with nanometer resolution. | Zijie Hua Dexin Ba Dengwang Zhou Yijia Li Yue Wang Xiaoyi Bao Yongkang Dong | 2021 | Light(Advanced Manufacturing)2021，2，4： | 1 |
| 5 | Micro EEG/ECG signal's chopper-stabilization amplifying chip for novel drycontact electrode显示文摘Facing the body's EEG(electroencephalograph, 0.5–100 Hz, 5–100 μV) and ECG's(electrocardiogram,< 100 Hz, 0.01–5 mV) micro signal detection requirement, this paper develops a pervasive application micro signal detection ASIC chip with the chopping modulation/demodulation method. The chopper-stabilization circuit with the RRL(ripple reduction loop) circuit is to suppress the ripple voltage, which locates at the single-stage amplifier's outputting terminal. The single-stage chopping core's noise has been suppressed too, and it is beneficial for suppressing noises of post-circuit. The chopping core circuit uses the PFB(positive feedback loop) to increase the inputting resistance, and the NFB(negative feedback loop) to stabilize the 40 dB intermediate frequency gain. The cascaded switch-capacitor sample/hold circuit has been used for deleting spike noises caused by non-ideal MOS switches, and the VGA/BPF(voltage gain amplifier/band pass filter) circuit is used to tune the chopper system's gain/bandwidth digitally. Assisted with the designed novel dry-electrode, the real test result of the chopping amplifying circuit gives some critical parameters: 8.1 μW/channel, 0.8 μVrms(@band-widthD100 Hz), 4216–11220 times digitally tuning gain range, etc. The data capture system uses the NI CO's data capturing DAQmx interface,and the captured micro EEG/ECG's waves are real-time displayed with the PC-Labview. The proposed chopper system is a unified EEG/ECG signal's detection instrument and has a critical real application value. | Jianhui Sun Chunxing Wang Gongtang Wang Jinhui Wang Qing Hua Chuanfu Cheng Xinxia Cai Tao Yin Yang Yu Haigang Yang Dengwang Li | 2017 | Journal of Semiconductors2017，38，2： | 1 |
| 6 | Niobium telluride absorber for a mode-locked vector soliton fiber laser显示文摘Niobium telluride(NbTe_(2)),an emerging transition metal dichalcogenide material,has been theoretically predicted to have nonlinear absorption properties and excellent optical response.However,only a few studies of the utilization of NbTe_(2)in ultrafast photonics have been reported.In this work,a NbTe_(2)-based saturable absorber(SA)was applied in an erbium-doped fiber as a mode-locked device,and a vector soliton based on NbTe_(2)was obtained for the first time.NbTe_(2)-PVA film SA was successfully prepared by the liquid-phase exfoliation and spin coating methods,with a modulation depth of up to 10.87%.The nonlinear absorption coefficient of NbTe_(2)-based SA film tested through the open-aperture Z-scan laser measurement is 0.62×10^(−11) m/W.A conventional soliton with a pulse duration of 858 fs was generated using NbTe_(2)-based SA,which was demonstrated to be a kind of polarization-locked vector soliton in further investigation.Our experimental results reveal the nonlinear optical properties of NbTe_(2)and broaden its applications in ultrafast photonic devices. | XinXin Shang NanNan Xu Jia Guo Shuo Sun HuaNian Zhang SWageh Ahmed AAl-Ghamdi Han Zhang DengWang Li | 2023 | Science China(Physics,Mechanics & Astronomy)2023，66，5： | 0 |
| 7 | Passive mode-locked Er-doped fiber laser pulse generation based on titanium disulfide saturable absorber显示文摘In this study,titanium disulfide(TiS_(2))polyvinyl alcohol(PVA)film-type saturable absorber(SA)is synthesized with a modulation depth of 5.08%and a saturable intensity of 10.62 MW/cm^(2) by liquid-phase exfoliation and spin-coating methods.Since TiS2-based SA has a strong nonlinear saturable absorption property,two types of optical soliton were observed in a mode-locked Er-doped fiber laser.When the pump power was raised to 67.3 mW,a conventional mode-locked pulse train with a repetition rate of 1.716 MHz and a pulse width of 6.57 ps was generated,and the output spectrum centered at 1556.98 nm and 0.466 nm spectral width with obvious Kelly sidebands was obtained.Another type of mode-locked pulse train with the maximum output power of 3.92 mW and pulse energy of 2.28 nJ at the pump power of 517.2 mW was achieved when the polarization controllers were adjusted.Since TiS2-based SA has excellent nonlinear saturable absorption characteristics,broad applications in ultrafast photonic are expected. | Xinxin SHANG Linguang GUO Huanian ZHANG Dengwang LI Qingyang YUE | 2021 | Frontiers of Information Technology & Electronic Engineering2021，22，5： | 0 |
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