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Chinese Physics B 2016年第7期25卷 250-257页

作者：郝杰巩马理杜鹏飞卢宝杰张帆张海涛付星 center for Photonics and Electronics Department of Precision Instrument Tsinghua University

A novel concept of collision avoidance single-photon light detection and ranging（LIDAR） for vehicles has been demonstrated, in which chaotic pulse position modulation is applied on the transmitted laser pulses for robust anti-crosstalk purposes. Besides, single-photon detectors（SPD） and time correlated single photon counting techniques are adapted, to sense the ultra-low power used for the consideration of compact structure and eye safety. Parameters including pulse rate, discrimination threshold, and number of accumulated pulses have been thoroughly analyzed based on the detection requirements, resulting in specified receiver operating characteristics curves. Both simulation and indoor experiments were performed to verify the excellent anti-crosstalk capability of the presented collision avoidance LIDAR despite ultra-low transmitting power.

关键词： collision avoidance chaotic pulse position modulation time-correlated single photon counting anti-crosstalk

Internal Features of Fiber Fuse in a Yb-Doped Double-Clad Fiber at 3 kW

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Chinese Physics Letters 2018年第5期35卷 29-33页

作者： Qi-Rong Xiao Jia-Ding Tian Yu-Sheng Huang Xue-Jiao Wang Ze-Hui Wang Dan Li Ping Yan Ma-Li Gong center for Photonics and Electronics Department of Precision Instrument Tsinghua University

We study internal features of fiber fuse in a Yb-doped double-clad fiber. The samples of fiber fuse are acquired at the power level of 3 kW in an all-fiber forward-pumped master oscillator power amplifier configuration fiber laser that is built specially for fiber fuse analyses. At this high power level, drastic refractive-index redistribution arises in an expended high refractive index area around the bullet-shaped voids of fiber fuse. Electron spin resonance analyses on post-fiber-fuse samples of the Yb-doped double-clad fiber indicate rising Frenkel defect concentration, meanwhile showing a new resonance center that is different from the ones of the Ge-doped fibers studied previously. This new resonance center probably suggests the generation of Al-oxygen hole center, a kind of defect formed during the catastrophic fuse process.

关键词： Fiber lasers

On-orbit real-time magnetometer bias determination for micro-satellites without attitude information

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Chinese Journal of Aeronautics 2015年第5期28卷 1503-1509页

作者： Zhang Zhen Xiong Jianping Jin Jin Department of Precision instrument Tsinghua University Space center Tsinghua University

Due to the disadvantages such as complex calculation, low accuracy of estimation, and being non real time in present methods, a new real-time algorithm is developed for on-orbit mag- netometer bias determination of micro-satellites without attitude knowledge in this paper. This method uses the differential value approach. It avoids the impact of quartic nature and uses the iterative method to satisfy real-time applications. Simulation results indicate that the new real-time algorithm is more accurate compared with other methods, which are also tested by an experiment system using real noise data. With the new real-time algorithm, a magnetometer calibration can be taken on-orbit and will reduce the demand for computing power effectively.

关键词： Magnetometer bias:On-orbit determinationMicro-satellite Attitude-independent Real-time

Investigations of range accuracy for long-range three-dimensional active imaging

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Chinese Optics Letters 2011年第6期9卷 48-50页

作者：张秀达严惠民周琴 State Key Laboratory of Modern Optical instrument National Engineering Research Center for Optical Instrument Optical Engineering Department Zhejiang University

Distance resolutions and noises are analyzed experimentally for long-range three-dimensional （3D） active imaging systems that have signal-to-noise ratios （SNRs） more optimal than 30：1. Findings indicate that the photon shot noise primarily determines the SNR. However, the active imaging method, which has a relatively low SNR, generates a relatively high distance resolution. To explain this phenomenon, a theory in which the distance resolution of 3D active imaging systems is determined by both the photon shot noise and the subinterval width is developed. Theoretical and experimental results differ by less than 4%.

关键词： Imaging systems Photons Shot noise Signal to noise ratio

Beyond Performance of Learning Control Subject to Uncertainties and Noise: A Frequency-Domain Approach Applied to Wafer Stages

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 198-214页

作者： Fazhi Song Ning Cui Shuaiqi Chen Kai Zhang Yang Liu Xinkai Chen Jiubin Tan IEEE the center of Ultra-precision Optoelectronic instrument Engineering Harbin Institute of Technology the Key Laboratory of Ultra-Precision Intelligent instrumentation Ministry of Industry and Information Technology the State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment Guangdong University of Technology the center of Ultraprecision Optoelectronic instrument Engineering Harbin Institute of Technology the Key Laboratory of UltraPrecision Intelligent instrumentation Ministry of Industry and Information Technology the Department of Electronic and Information Systems Shibaura Institute of Technology

The increasingly stringent performance requirement in integrated circuit manufacturing, characterized by smaller feature sizes and higher productivity, necessitates the wafer stage executing a extreme motion with the accuracy in terms of nanometers. This demanding requirement witnesses a widespread application of iterative learning control(ILC), given the repetitive nature of wafer scanning. ILC enables substantial performance improvement by using past measurement data in combination with the system model knowledge. However, challenges arise in cases where the data is contaminated by the stochastic noise, or when the system model exhibits significant uncertainties, constraining the achievable performance. In response to this issue, an extended state observer(ESO) based adaptive ILC approach is proposed in the frequency *** being model-based, it utilizes only a rough system model and then compensates for the resulting model uncertainties using an ESO, thereby achieving high robustness against uncertainties with minimal modeling effort. Additionally, an adaptive learning law is developed to mitigate the limited performance in the presence of stochastic noise, yielding high convergence accuracy yet without compromising convergence speed. Simulation and experimental comparisons with existing model-based and data-driven inversion-based ILC validate the effectiveness as well as the superiority of the proposed method.

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All-fiber linearly polarized laser oscillator by fiber coiling loss control

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Chinese Physics B 2018年第4期27卷 305-308页

作者： Yu-Sheng Huang Qi-Rong Xiao Dan Li Ze-Hui Wang Xue-Jiao Wang Ping Yan Ma-Li Gong center for Photonics and Electronics Department of Precision Instrument Tsinghua University Beijing 100084 China

In this paper,we demonstrate an all-fiber linearly polarized fiber laser *** single polarization of the oscillator is achieved through the careful designing of the active fiber *** relationship between fiber coiling diameter and polarization extinction ratio and optical efficiency is studied,whose results lead to an optimized *** thermal management of the oscillator is also refined,which allows the oscillator to reach a maximum output power of44.1 W with an optical-to-optical efficiency of 57.9%.A high average polarization extinction ratio of 21.6 d B is achieved during a 2-hour stability *** oscillator also owns a narrow 3-d B bandwidth of 0.1 nm,as well as near-diffraction-limit beam quality of M^2～ 1.14.

关键词： fiber laser oscillator linearly polarized all-fiber

Influence of mode competition on beam quality of fiber amplifier

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Chinese Physics B 2014年第10期23卷 235-241页

作者：肖起榕闫平孙骏逸陈霄任海翠巩马理 center for Photonics and Electronics State Key Laboratory of Tribology Department of Precision Instrument Tsinghua University

Theoretical and experimental studies of the influence of the mode competition on the output beam quality of fiber amplifiers are presented. Rate equations and modal decomposition method are used in the theoretical model. In the experiment, the output beam-quality factor of a fiber amplifier, which is based on a Yb-doped double-clad large mode area fiber as a function of the seed beam quality and the pump power of the amplifier, is measured. The experimental results are consistent with the theoretical analysis.

关键词： fiber laser and amplifier mode competition beam quality

Fiber fuse behavior in kW-level continuous-wave double-clad field laser

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Chinese Physics B 2016年第1期25卷 600-603页

作者：孙骏逸肖起榕李丹王雪娇张海涛巩马理闫平 center for Photonics and Eleconics Department of Precision InstrumentTsinghua UniversityBeijing 100084China

In this study, original experimental data for fiber fuse in kW-level continuous-wave （CW） high power double-clad fiber （DCF） laser are reported. The propagating velocity of the fuse is 9.68 m/s in a 3.1-kW Yb-doped DCF laser. Three other cases in Yb-doped DCF are also observed. We think that the ignition of fiber fuse is caused by thermal mechanism, and the formation of bullet-shaped tracks is attributed to the optical discharge and temperature gradient. The inducements of initial fuse and formation of bullet-shaped voids are analyzed. This investigation of fiber fuse helps better understand the fiber fuse behavior, in order to avoid the catastrophic destruction caused by fiber fuse in high power fiber laser.

关键词： fiber lasers high power lasers laser damage

Multi-grained system integration for hybrid-paradigm brain-inspired computing

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Science China(Information Sciences) 2023年第4期66卷 272-285页

作者： Jing PEI Lei DENG Cheng MA Xue LIU Luping SHI Department of Precision instrument Center for Brain Inspired Computing Research(CBICR) Beijing Innovation Center for Future Chip Tsinghua University

Hybrid neuromorphic computing supporting the prevailing artificial neural networks and neuroscience-inspired models/algorithms offers substantial flexibility for cross-paradigm model *** is one of the most promising technologies for accelerating intelligence development, ultimately contributing to artificial general intelligence development. Recently, an increasing number of hybrid neuromorphic computing chips have been reported, but such research focuses on chip design without demonstrating systems for large-scale workloads. To this end, we construct a multi-grained system based on many Tianjic chips, presenting a large-scale system for hybrid-paradigm brain-inspired computing. With different numbers of chips and different connection topologies, we develop a Tianjic card and a Tianjic board as the infrastructure for building embedded systems and cloud servers, respectively. Extensive measurements of the communication latency, computational latency, and power consumption evidence the superior potential of Tianjic systems for exploring brain-inspired computing for artificial general intelligence.

关键词： brain-inspired computing multi-grained system integration hybrid paradigm Tianjic chip brain-inspired platform

Hybrid neural state machine for neural network

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Science China(Information Sciences) 2021年第3期64卷 136-148页

作者： Lei TIAN Zhenzhi WU Shuang WU Luping SHI Department of Precision instrument Center for Brain-Inspired Computing Research(CBICR)Beijing Innovation Center for Future Chip Tsinghua University

The integration of computer-science-oriented and neuroscience-oriented approaches is believed to be a promising way for the development of artificial general intelligence(AGI). Recently, a hybrid Tianjic chip that integrates both approaches has been reported, providing a general platform to facilitate the research of AGI. The control algorithm for handling various neural networks is the key to this platform; however, it is still primitive. In this work, we propose a hybrid neural state machine(H-NSM) framework that can efficiently cooperate with artificial neural networks and spiking neural networks and control the workflows to accomplish complex tasks. The H-NSM receives input from different types of networks, makes decisions according to the fusing of various information, and sends control signals to the sub-network or actuator. The H-NSM can be trained to adapt to context-aware tasks or sequential tasks, thereby improving system robustness. The training algorithm works correctly even if only 50% of the forced state information is provided. It achieved performance comparable to the optimum algorithm on the Tower of Hanoi task and achieved multiple tasks control on a self-driving bicycle. After only 50 training epochs, the transfer accuracy reaches 100% in the test case. It proves that H-NSM has the potential to advance control logic for hybrid systems, paving the way for designing complex intelligent systems and facilitating the research towards AGI.

关键词： hybrid neural state machine ANNs SNNs supervised learning context-aware task sequential task