1 电子科技大学光纤传感与通信教育部重点实验室，四川 成都 611731
2 之江实验室光纤传感研究中心，浙江 杭州 311121
光脉冲编码（OPC）近年来在光纤声波传感领域备受关注，特别是将其与相位敏感光时域反射仪（Φ-OTDR）相结合的技术。通过对注入光纤中的探测脉冲进行编码，可在不增加脉冲峰值功率的情况下大幅提高传感信号的信噪比，同时避免了非线性效应的影响；在接收端解码后可获得单脉冲响应，系统空间分辨率由单个脉冲而不是整个探测脉冲序列的长度决定，从而在获得高信噪比传感信号的同时保持了空间分辨率。本文首先回顾了OPC在光纤声波传感领域中的发展历程；然后，重点介绍了本课题组基于OPC的分布式和准分布式声波传感研究进展，特别是在传感带宽提升方面的成效；最后，对基于OPC的光纤声波传感技术未来发展方向进行了探讨。
光纤传感 光脉冲编码 分布式声波传感 相位敏感光时域反射仪
电子科技大学光纤传感与通信教育部重点实验室，四川 成都 611731
拉曼光纤随机激光结合无源传感单元可以实现超长距离的准分布式传感。然而，受限于光谱探测速度，该传感方案通常只适用于静态传感领域。针对该问题，将拉曼光纤随机激光与拍频光谱探测技术相结合，提出了一种新型的拉曼光纤随机激光长距离动态传感技术。首先，基于含时光谱稳态模型论证了光谱快速测量对长距离动态传感的适用性。随后，在原理性验证实验中通过处理本振光与光纤随机激光拍频后的时域信号，实现了对光纤随机激光光谱的快速测量，并突破了光波往返时间对传感带宽的限制。同时，利用去噪卷积神经网络对光谱的中心波长变化进行标定，大幅提高了扰动信号探测的信号质量，实现了对不同频率、不同波形的扰动信息的准确测量。该研究为进一步拓展光纤随机激光的应用领域提供了新的思路。
光纤传感 光纤随机激光 拉曼散射 瑞利散射 去噪卷积神经网络 激光与光电子学进展
2023, 60(11): 1106027
Author Affiliations
Abstract
1 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
2 Graduate School of China Academy of Engineering Physics, Beijing 100193, China
3 Key Laboratory of Optical Fiber Sensing and Communications, University of Electronic Science and Technology of China, Chengdu 611731, China
Matter and Radiation at Extremes
2023, 8(2): 029901
Author Affiliations
Abstract
1 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
2 Graduate School of China Academy of Engineering Physics, Beijing 100193, China
3 Key Laboratory of Optical Fiber Sensing and Communications, University of Electronic Science and Technology of China, Chengdu 611731, China
Broadband low-coherence light is considered to be an effective way to suppress laser plasma instability. Recent studies have demonstrated the ability of low-coherence laser facilities to reduce back-scattering during beam–target coupling. However, to ensure simultaneous low coherence and high energy, complex spectral modulation methods and amplification routes have to be adopted. In this work, we propose the use of a random fiber laser (RFL) as the seed source. The spectral features of this RFL can be carefully tailored to provide a good match with the gain characteristics of the laser amplification medium, thus enabling efficient amplification while maintaining low coherence. First, a theoretical model is constructed to give a comprehensive description of the output characteristics of the spectrum-tailored RFL, after which the designed RFL is experimentally realized as a seed source. Through precise pulse shaping and efficient regenerative amplification, a shaped random laser pulse output of 28 mJ is obtained, which is the first random laser system with megawatt-class peak power that is able to achieve low coherence and efficient spectrum-conformal regenerative amplification.
Matter and Radiation at Extremes
2023, 8(2): 025902
Author Affiliations
Abstract
Key Laboratory of Optical Fiber Sensing & Communications (Ministry of Education), University of Electronic Science and Technology of China, Chengdu 611731, China
Cascaded random Raman fiber lasers (CRRFLs) have been used as a new platform for designing high power and wavelength-agile laser sources. Recently, CRRFL pumped by ytterbium-doped random fiber laser (YRFL) has shown both high power output and low relative intensity noise (RIN). Here, by using a wavelength- and bandwidth-tunable point reflector in YRFL, we experimentally investigate the impacts of YRFL on the spectral and RIN properties of the CRRFL. We verify that the bandwidth of the point reflector in YRFL determines the bandwidth and temporal stability of YRFL. It is found that with an increase in the bandwidth of the point reflector in YRFL from 0.2 nm to 1.4 nm, CRRFL with higher spectral purity and lower RIN can be achieved due to better temporal stability of YRFL pump. By broadening the point reflector’s bandwidth to 1.4 nm, the lasing power, spectral purity, and RIN of the 4th-order random lasing at 1 349 nm can reach 3.03 W, 96.34%, and –115.19 dB/Hz, respectively. For comparison, the spectral purity and RIN of the 4th-order random lasing with the point reflector’s bandwidth of 0.2 nm are only 91.20% and –107.99 dB/Hz, respectively. Also, we realize a wavelength widely tunable CRRFL pumped by a wavelength-tunable YRFL. This work provides a new platform for the development of ideal distributed Raman amplification pump sources based on CRRFLs with both good temporal stability and wide wavelength tunability, which is of great importance in applications of optical fiber communication and distributed sensing.
Random fiber laser Raman fiber laser relative intensity noise distributed Raman amplification Photonic Sensors
2022, 12(4): 220414
Author Affiliations
Abstract
Key Lab of Optical Fiber Sensing & Communications, University of Electronic Science &Technology of China, Chengdu 611731, China
In this paper, a novel birefringence measurement method through the Rayleigh backscattered lightwave within single-mode fiber is proposed, using a single chirped-pulse with arbitrary state of polarization. Numerical analysis is carried out in detail, then pulse-compression phase-sensitive optical time domain reflectometry (PC-Φ-OTDR) with polarization-diverse coherent detection is employed to verify this method. A 2 km spun single-mode fiber is tested with 8.6 cm spatial resolution, and the average birefringence of the fiber under test is measured as 0.234 rad/m, which is consistent with previous literatures about single-mode fiber. Moreover, the relationship between the measured birefringence and the spatial resolution is also studied for the first time, and the results show that spatial resolution is crucial for fiber birefringence measurement.
Birefringence Rayleigh scattering pulse-compression phase-sensitive optical time-domain reflectometry coherent detection polarization-diverse receiver Photonic Sensors
2021, 11(4): 402
强激光与粒子束
2021, 33(11): 111003
Author Affiliations
Abstract
1 Key Lab of Optical Fiber Sensing & Communications, University of Electronic Science & Technology of China, Chengdu 611731, China
2 Metrology and Testing Center, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
3 National Institute for Laser, Plasma and Radiation Physics Center for Advanced Laser Technologies, Magurele RO-077125, Romania
4 “Horia Hulubei” National Institute of Physics and Nuclear Engineering, MAgurele RO-077125, Romania
5 Photonics and Optical Communications, The University of New South Wales (UNSW), Sydney 2052, Australia
The effects of gamma ray (γ-ray) radiation and electron beam (e-beam) radiation on Rayleigh scattering coefficient in single-mode fiber are experimentally investigated. Utilizing an optical time domain reflectometry (OTDR), the power distribution curves of the irradiated fibers are obtained to retrieve the corresponding radiation-induced attenuation (RIA). Based on the backscattering power levels and the measured RIAs, the Rayleigh scattering coefficients can be characterized quantitatively for each fiber sample. Under the given radiation conditions, Rayleigh scattering coefficients have been changed very little while RIAs have been changed significantly. Furthermore, simulations have been implemented to verify the validity of the measured Rayleigh scattering coefficient, including the splicing points.
Gamma ray electron beam Rayleigh scattering radiation-induced attenuation Rayleigh scattering coefficient Photonic Sensors
2021, 11(3): 298
1 电子科技大学光纤传感与通信教育部重点实验室，四川 成都 611731
2 电子科技大学信息地学研究中心，四川 成都 611731
3 中国工程物理研究院激光聚变研究中心，四川 绵阳 621900
4 之江实验室光纤传感研究中心，浙江 杭州 311121
基于光纤瑞利散射的相位敏感光时域反射仪（Φ-OTDR），具有对环境变化敏感、响应速度快等特点，是分布式光纤传感领域最重要的分支之一。然而，Φ-OTDR使用的高相干探测光波在散射过程中会不可避免地出现干涉衰落效应，相应位置会成为传感的盲区。此现象是多年来本领域的关注重点之一。本文首先简述了干涉衰落的产生机理和数学特征；然后，系统地介绍了Φ-OTDR的典型传感机制，以及干涉衰落对传感信号解调造成的影响；随后，全面地回顾了Φ-OTDR抗干涉衰落技术的研究历程；最后，对Φ-OTDR的未来发展进行了探讨。
激光与光电子学进展
2021, 58(13): 1306008
电子科技大学光纤传感与通信教育部重点实验室, 四川 成都 611731
自光纤随机激光器概念提出以来,光纤随机激光已经在光纤激光、光纤传感等领域得到了广泛关注。将光纤随机激光与光纤光栅相结合,基于光纤光栅的光谱变化信息可以实现高性能点式传感系统,因此,此类系统的光谱特征决定了传感距离、精度和复用能力等关键参数。针对高阶随机激光多点传感系统中光谱特性仿真这一关键问题,对传统的高阶随机激光功率稳态模型进行改进,所提出的模型的光谱仿真结果均与实验高度吻合。基于该仿真模型,设计并实现了长达150 km的高阶光纤随机激光多点传感系统。同时,实验得到的传感信号波长与应变的线性拟合度高达0.999,充分验证了该系统的传感性能。
光学学报
2021, 41(13): 1306006
