上海大学特种光纤与光接入网重点实验室,特种光纤与先进通信国际联合研究实验室,上海 200444
在通信波段研究了基于亚波长尺寸微纳光纤的光热光谱气体传感技术,利用锥腰直径为1 μm的微纳光纤代替传统的自由空间光气室和空芯光纤实现紧凑的全光纤结构,其引导的倏逝场被气体吸收后会激发光热效应。仿真结果表明,约25%的光波以倏逝场的形式沿光纤表面传播,可提供的光热效应强度约为空芯光纤的187倍。通过外差干涉法在微纳光纤提供的4 mm超短有效传感光程上实现了1512.24 nm处10-6级别氨气(NH3)检测。当使用的泵浦光功率为3.6 mW时,得到1σ噪声等效检测下限为39×10-6,30个泵浦调谐周期内探测信号的不稳定性小于0.5%。
光谱学 光热光谱 微纳光纤 外差干涉 光纤传感器 NH3检测 光学学报
2023, 43(16): 1623026
红外与激光工程
2023, 52(6): 20230292
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
2 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China
An all-fiberized random distributed feedback Raman fiber laser (RRFL) with mode output at 1134 nm has been demonstrated experimentally, where an intracavity acoustically induced fiber grating is employed for modal switching. The maximum output power of mode is 93.8 W with the modal purity of 82%, calculated by numerical mode decomposition technology based on stochastic parallel-gradient descent algorithm. To our best knowledge, this is the highest output power with high purity of mode generated from the RRFL. This work may pave a path towards advanced fiber lasers with special temporal and spatial characteristics for applications.
acoustically induced fiber grating LP11 mode mode decomposition random distributed feedback Raman fiber laser Chinese Optics Letters
2023, 21(2): 021406
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
2 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200444, China
A hundred-watt-level spatial mode switchable all-fiber laser is demonstrated based on a master oscillator power amplifier scheme. The performance of the amplifier with two seed lasers, i.e., with the acoustically induced fiber grating (AIFG) mode converter inside and outside the seed laser cavity, is investigated. Real-time mode switching with millisecond scale switching time between the and modes while operating in full power () is realized through an AIFG driven by radio frequency modulation. This work could provide a good reference for realizing high-power agile mode switchable fiber lasers for practical applications.
acoustically induced fiber grating high power fiber amplifier mode switching Chinese Optics Letters
2022, 20(2): 021402
特种光纤与光接入网重点实验室,特种光纤与先进通信国际合作联合实验室,上海先进通信与数据科学研究院,上海大学,上海 200444
本文基于TDLAS技术,采用设计制备的微纳光纤气体吸收池,搭建了一套全光纤的NH3浓度检测系统。NH3检测系统的核心部分气体传感通过1.51 μm的微纳光纤完成,该系统检测结果表明,NH3在20000 ppm-100000 ppm浓度范围内,解调的二次谐波幅值与对应浓度之间具有良好的线性关系(拟合方程相关系数R=0.9962)。为了提高NH3浓度的检测性能,采用纳米金涂覆微纳光纤以增强光纤的倏逝场效应。根据实验结果,纳米金涂覆后的微纳光纤NH3浓度检测系统灵敏度有了很大提升,NH3浓度的检测下限可达到260 ppm。对不同浓度的NH3反复监测显示该检测系统稳定性良好,最大相对误差为5.38%,适用于长期稳定性的NH3监测,具有广泛的应用前景。
TDLAS技术 微纳光纤 纳米金涂覆 NH3浓度检测 technology of TDLAS microfiber gold-nanosphere coating NH3 concentration detection
特种光纤与光接入网重点实验室,特种光纤与先进通信国际合作联合实验室,上海先进通信与数据科学研究院,上海大学,上海 200444
本文提出了一种可以实现光纤高阶模式(HOM)在激光腔内振荡的锁模掺镱光纤激光器。通过使用一对级联的模式选择耦合器(MSC)作为有效的模式转换器,获得光纤锁模激光腔内HOM产生。其中,制备的MSC中心波长为1064 nm,可实现80 nm的模式转换带宽和94%的高阶模式纯度。通过搭建掺镱锁模光纤激光器,实验获得了3 dB谱宽7.4 nm、脉冲重复频率10.9 MHz、射频信噪比55 dB的锁模脉冲激光,输出功率的斜率效率为2.3%。实验证明,这种方法可在激光器内部通过模式级联转换,且能参与腔内锁模过程获得脉冲HOM激光。
模式选择耦合器 高阶模式 掺镱光纤 锁模光纤激光器 mode-selective couplers high-order mode Yb-doped fibers mode-locking fiber lasers
上海大学先进通信与数据科学研究院, 特种光纤与光接入网重点实验室, 特种光纤与先进通信国际合作联合实验室, 上海 200444
基于腔内的模式选择耦合器(MSC),报道了一种输出模式可切换的调Q脉冲掺铒光纤激光器。通过布拉格光栅和MSC的共同作用,实现输出波长的选择和不同模式间的转换。由于MSC具有模式分离特性且激光腔具有双支路输出配置,通过调整腔内损耗可以实现对激光输出不同模式间的切换,成功地观察到了同时具有线偏振模式(LP01模式和LP11模式)的双波长调Q脉冲输出,该模式可切换激光器可以应用在通信、粒子捕获等领域。
激光器 调Q光纤激光器 双波长 可调横模 少模布拉格光栅 中国激光
2020, 47(12): 1201001
Author Affiliations
Abstract
1 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai University, Shanghai 200444, China
2 Department of Electronic Engineering, School of Information Science and Engineering, Xiamen University, Xiamen 361005, China
3 Shenzhen Key Laboratory of Laser Engineering, Shenzhen University, Shenzhen 518060, China
4 e-mail: ffpang@shu.edu.cn
Temporal and spatial resonant modes are always possessed in physical systems with energy oscillation. In ultrafast fiber lasers, enormous progress has been made toward controlling the interactions of many longitudinal modes, which results in temporally mode-locked pulses. Recently, optical vortex beams have been extensively investigated due to their quantized orbital angular momentum, spatially donut-like intensity, and spiral phase front. In this paper, we have demonstrated the first to our knowledge observation of optical vortex mode switching and their corresponding pulse evolution dynamics in a narrow-linewidth mode-locked fiber laser. The spatial mode switching is achieved by incorporating a dual-resonant acousto-optic mode converter in the vortex mode-locked fiber laser. The vortex mode-switching dynamics have four stages, including quiet-down, relaxation oscillation, quasi mode-locking, and energy recovery prior to the stable mode-locking of another vortex mode. The evolution dynamics of the wavelength shifting during the switching process are observed via the time-stretch dispersion Fourier transform method. The spatial mode competition through optical nonlinearity induces energy fluctuation on the time scale of ultrashort pulses, which plays an essential role in the mode-switching dynamic process. The results have great implications in the study of spatial mode-locking mechanisms and ultrashort laser applications.
Photonics Research
2020, 8(7): 07001203
上海大学特种光纤与光接入网重点实验室, 特种光纤与先进通信国际合作联合实验室, 上海先进通信与数据科学研究院, 上海 200444
对模式选择耦合器、声致光纤光栅等全光纤模式转换器件的工作原理进行总结,并结合锁模光纤激光器和模式转换器件的优势,简单高效地产生了超快矢量光束和涡旋光束,得到的超快高阶模式激光具有峰值功率高、模式纯度高等特点。实验证明了模式转换器件的快速响应特性和宽带模式转换特性,并指出了其未来的发展方向和应用前景。
光纤激光器 超快光学 高阶模式 模式选择耦合器 声致光纤光栅