上海大学通信与信息工程学院，特种光纤与光接入网省部共建国家重点实验室培育基地，特种光纤与先进通信国际合作联合实验室，上海 200444
传统的光学透镜存在体积较大、聚焦效率低、焦点半峰全宽较大以及在高数值孔径的透镜中性能表现不佳等问题。而光学超表面凭借其自身的亚波长结构，具有强大的操控光相位的能力。相比于传统透镜，超透镜具有尺寸小、厚度薄以及聚焦性能好等优点。本文提出一种基于目标优先算法的逆向设计方法，设计了一种基于低折射率聚合物材料的超透镜结构。其在传播方向上的厚度仅为3.2 μm，在1550 nm的工作波长下，数值孔径为0.82，聚焦效率为72%。较传统设计方法而言，该方法具有计算复杂度低和设计效率高等优点。设计的器件可采用高精度微纳打印技术实现批量化的快速制造。考虑到超透镜在制备过程中存在制造容差，进一步讨论了超透镜轮廓偏移以及三维旋转操作对所设计的二维超透镜的影响。
超表面 超透镜 逆向设计 目标优先算法 偏振不依赖性
Author Affiliations
Abstract
1 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China
2 Key Laboratory for Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
3 Key Laboratory of Space Laser Communication and Detection Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
4 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
We demonstrate a simultaneous transmission of time-frequency and data over a 160-km urban business network in Shanghai. The signals are transmitted through a cascaded optical link consisting of 48 km and 32 km, which are connected by an optical relay. The metrological signals are inserted into the communication network using dense wavelength division multiplexing. The influence of the interference between different signals has been discussed. The experimental results demonstrate that the radio frequency (RF) instability can reach at 1 s and at 10,000 s, and the time interval transfer of one pulse per second (1 PPS) signal with less than 10 ps at 1 s is obtained. This work paves the way for the widespread dissemination of ultra-stable time and frequency signals over the communication networks.
simultaneous transmission radio frequency transfer communication network wavelength multiplexing Chinese Optics Letters
2024, 22(1): 011201
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 Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China
2 Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
Replica symmetry breaking (RSB), as a featured phase transition between paramagnetic and spin glass state in magnetic systems, has been predicted and validated among random laser-based complex systems, which involves numerous random modes interplayed via gain competition and exhibits disorder-induced frustration for glass behavior. However, the dynamics of RSB phase transition involving micro-state evolution of a photonic complex system have never been well investigated. Here, we report experimental evidence of transient RSB in a Brillouin random fiber laser (BRFL)-based photonic system through high-resolution unveiling of random laser mode landscape based on heterodyne technique. Thanks to the prolonged lifetime of activated random modes in BRFLs, an elaborated mapping of time-dependent statistics of the Parisi overlap parameter in both time and frequency domains was timely resolved, attributing to a compelling analogy between the transient RSB dynamics and the random mode evolution. These findings highlight that BRFL-based systems with the flexible harness of a customized photonic complex platform allow a superb opportunity for time-resolved transient RSB observation, opening new avenues in exploring fundamentals and application of complex systems and nonlinear phenomena.
Author Affiliations
Abstract
Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China
Fiber quarter-wave plates and magneto-optical fibers are important components that greatly affect the sensitivity of fiber-optic current sensors. A Tb:YAG crystal-derived silica fiber (TYDSF) was fabricated using a laser-heating drawing technique. The linear birefringence of TYDSF was measured as by a microscope birefringence measurement instrument. A fiber quarter-wave plate was fabricated by TYDSF at 1310 nm, which produced circularly polarized light with a polarization extinction ratio of 0.34 dB. Additionally, the linear birefringence of TYDSF was decreased by 22% by annealing at 750°C for 7 h, and the Verdet constants of annealed TYDSF were measured to be 9.83, 6.67, and at 808, 980, and 1310 nm, respectively.
Faraday effect linear birefringence fiber quarter-wave plate Chinese Optics Letters
2023, 21(11): 110601
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 School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China
3 State Key Laboratory of Advanced Optical Communication Systems and Networks, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
4 Center for Smart Structures and Materials, Northwestern University, Evanston, Illinois 60208, USA
5 e-mail: sridhar.krishnaswamy@northwestern.edu
Optical fiber microresonators have attracted considerable interest for acoustic detection because of their compact size and high optical quality. Here, we have proposed, designed, and fabricated a spring-based Fabry–Pérot cavity microresonator for highly sensitive acoustic detection. We observed two resonator vibration modes: one relating to the spring vibration state and the other determined by the point-clamped circular plate vibration mode. We found that the vibration modes can be coupled and optimized by changing the structure size. The proposed resonator is directly 3D printed on an optical fiber tip through two-photon polymerization and is used for acoustic detection and imaging. The experiments show that the device exhibits a high sensitivity and low noise equivalent acoustic signal level of at 75 kHz that can detect weak acoustic waves, which can be used for underwater object imaging. The results demonstrate that the proposed work has great potential in acoustic detection and biomedical imaging applications.
Photonics Research
2023, 11(5): 780
上海大学通信与信息工程学院特种光纤与光接入网重点实验室，上海 200444
提出了一种基于环形芯结构的掺铒涡旋光纤。针对该涡旋光纤的放大性能，分析了其高折射率环和掺杂区域宽度对增益性能的影响。仿真结果表明，该光纤可支持1~2阶涡旋光模式，且C波段内的模式增益均高于35.4 dB。通过搭建实验装置对环形芯掺铒涡旋光纤的放大性能进行了测试。实验结果表明，在1530 nm波长处涡旋光的模式增益最大值高达32.6 dB。此环形芯掺铒涡旋光纤可广泛应用在长距离、大容量的空分复用光纤通信等领域中。
光纤光学 掺铒光纤 环形芯光纤 涡旋光模式 增益 中国激光
2023, 50(10): 1006003
上海大学特种光纤与光接入网省部共建国家重点实验室培育基地，特种光纤与先进通信国际合作联合实验室，上海 200444
为了解决随机线性双折射对光纤磁光特性测量的影响，采用旋转光纤（SF）结合法拉第旋转镜（FRM）的测量方法，研究了FRM对旋转光纤磁光特性测量的影响。首先，从理论方面研究旋转光纤与FRM的引入如何减小光纤中的随机线性双折射对磁光特性测量的影响，并搭建基于FRM的旋转光纤磁光特性测试系统。当光源波长为1310 nm时，FRM作用前的旋转光纤费尔德常数都比未旋转光纤的大，且旋转光纤的节距越短，费尔德常数越大。特别是旋转光纤的节距为1.0 mm时，其费尔德常数为0.8304 rad/（T·m），比未旋转光纤的费尔德常数［0.8029 rad/（T·m）］增大了约3.43%。当测试系统加入FRM后，不同光纤的费尔德常数测量值相较于未使用FRM的光纤费尔德常数测量值都有一定幅度的增大，尤其相比于节距为1.0 mm时的旋转光纤更进一步提高了7.50%，并且在FRM作用前后不同光纤费尔德常数测量值的均方差分别为0.99%和0.61%，说明FRM的引入提高了掺杂光纤费尔德常数的测量精度与稳定性。
测量 法拉第效应 磁光特性 法拉第旋转镜 费尔德常数 双折射
Author Affiliations
Abstract
Laboratory of Specialty Fiber Optics and Optical Access Networks, School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China
We fabricate a high-performance Bi/Er/La co-doped silica fiber with a fluorescence intensity of and a gain coefficient of 1.9 dB/m. With the utilization of the fiber as a gain medium, a linear-cavity fiber laser has been constructed, which exhibits a signal-to-noise ratio of 74.9 dB at 1596 nm. It has been demonstrated that the fiber laser has a maximum output power of 107.4 mW, a slope efficiency of up to 17.0%, and a linewidth of less than 0.02 nm. Moreover, an all-fiber single-stage optical amplifier is built up for laser amplification, by which the amplified laser power is up to 410.0 mW with pump efficiency of 33.8%. The results indicate that the laser is capable of high signal-to-noise ratio and narrow linewidth, with potential applications for optical fiber sensing, biomedicine, precision measurement, and the pump source of the mid-infrared fiber lasers.
Bi/Er/La co-doped silica fiber high signal-to-noise ratio laser narrow linewidth Chinese Optics Letters
2022, 20(5): 051402
上海大学特种光纤与光接入网省部共建国家重点实验室培育基地，特种光纤与先进通信 国际合作联合实验室，上海 200444
超声波在金属、陶瓷等不透明介质中具有强穿透特性，其作为感测单元的超声安全监测技术已成为一种重要的检测工具。与传统的压电超声传感器相比，光纤超声传感器具有较强的抗干扰性、复用性、高灵敏性和宽探测频带，在结构无损探测和电力安全系统等领域具有大量的应用。针对安全监测中声发射信号的特性以及探测手段，主要综述了光纤超声传感技术以及光纤超声在安全监测领域中的应用，并就光纤超声传感机理、传感方法以及传感过程中存在的问题进行深入分析，最后对本领域未来潜在的发展方向和应用价值进行讨论。
激光与光电子学进展
2021, 58(13): 1306018
