西安理工大学自动化与信息工程学院，陕西 西安 710048
针对模拟信号进行时延估计时相比解调过的信号更易受到噪声影响，导致出现误判点增多、正确峰值被掩盖等问题。本文提出采用奇异谱分解结合改进的广义相关法，降低高斯噪声对时延估计结果的影响。Simulink仿真实验表明，相比于解调信号时延估计法，该方法可在更低发射频率需求下得到同量级精度的故障类型和距离信息。在5 dB高斯噪声环境下多次实验验证可得，相比二次相关法结果主峰值旁瓣比绝对值增加了0.6756 dB以上，误判峰值与故障点峰值比减少了0.2710以上，其他条件下亦有不同程度提升。
光纤光学与光通信 时延估计 奇异谱分解 广义互相关 激光与光电子学进展
2024, 61(5): 0506008
1 南京理工大学电子工程与光电技术学院，江苏 南京 210094
2 南京理工大学先进固体激光工信部重点实验室，江苏 南京 210094
激光光束质量因子的动态测量对激光器的设计、制造与应用均具有重要意义。本文提出了一种基于远场同轴全息的光纤激光器光束质量因子动态测量方法。通过偏振移相同轴全息技术直接获取待测激光的远场复振幅信息，利用角谱传输及透镜变换理论求解激光在自由空间中的光场强度分布，从而实现因子的动态测量。实验搭建了远场同轴全息装置，测量了不同纤芯直径光纤在632.8 nm 波长下的激光光束质量，其结果与BEAM SQUARED商用光束质量仪的测量结果一致。本文所提方法仅需0.02 s即可实现光纤激光的因子测量，比商用光束质量仪的测量速度提高了两个数量级以上。此外，本装置结构紧凑，能够避免透镜引入的装调及加工误差。
光纤光学与光通信 光束质量M2因子 同轴移相干涉 角谱传输 透镜变换 光学学报
2023, 43(14): 1406001
西安邮电大学电子工程学院，陕西 西安 710121
为提高光纤无线电（RoF）系统的传输性能，提出了一种基于概率-几何混合整形的圆形正交振幅调制（PS-GS-Cir-MQAM）矢量太赫兹信号传输方案。在Matlab和VPI环境下联合仿真分析了130 GHz波段PS-GS-Cir-MQAM信号在强度调制器（IM）和同相/正交（I/Q）调制器级联的RoF系统中信号的传输性能，并比较分析了信号的误码性能在不同整形方法后的改善效果。结果表明，提出的PS-GS-Cir-MQAM太赫兹信号的误码性能均优于其他三种整形格式。其中PS-GS-Cir-32QAM信号的误码性能提升效果最为明显，相比其他三种整形格式，分别提升了0.88、1.40、2.48 dB的信号功率增益。尤其是在克服光器件和光纤的非线性效应方面，PS-GS-Cir-MQAM的矢量太赫兹信号具有更大的传输优势。
光纤光学与光通信 矢量太赫兹信号 混合整形 概率整形 几何整形 非线性效应 激光与光电子学进展
2023, 60(9): 0906001
Author Affiliations
Abstract
1 Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
2 Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China
Fiber Bragg grating has been successfully fabricated in the silica microfiber by the use of femtosecond laser point-by-point inscription. Temporal thermal response of the fabricated silica microfiber Bragg grating has been measured by the use of the CO2 laser thermal excitation method, and the result shows that the time constant of the microfiber Bragg grating is reduced by an order of magnitude compared with the traditional single-mode fiber Bragg grating and the measured time constant is ~ 21 ms.
Fiber optics sensors fiber optics and optical communications fiber optics components Photonic Sensors
2021, 11(4): 387
Author Affiliations
Abstract
Advanced Membrane Technology Research Centre (AMTEC), University Technology Malaysia, Skudai 81310, Malaysia
Miniature optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and a transducer to get response and feedback from environments, in which optical fibers act as a signal carrier. A novel Ag coated intensity modulated optical fiber sensor based on refractive index changes using IR and UV-Vis (UV-visible) light sources is proposed. The sensor with an IR light source has higher sensitivity compared to a UV-Vis source. When the refractive index is enhanced to 1.38, the normalized intensity of IR and UV-Vis light diminishes to 0.2 and 0.8, respectively.
060.0060 Fiber optics and optical communications 310.6188 Spectral properties 120.4570 Optical design of instruments Chinese Optics Letters
2018, 16(9): 090602
Author Affiliations
Abstract
Photonics Research Centre, University of Malaya, Kuala Lumpur 50603, Malaysia
A stable, passively Q-switched thulium fluoride fiber laser (TFFL) using a multi-walled carbon nanotube (MWCNT)-based saturable absorber (SA) for operation in the S-band region is proposed and demonstrated. The proposed TFFL has a central lasing wavelength of 1486.4 nm and an input power range of 87.1–126.6 mW. The output pulses have a repetition rate and pulse width range of 30.1–40.0 kHz and 9.0–3.2 μs, respectively, with a maximum pulse energy of 28.9 nJ. This is the first time, to the author’s knowledge, of the successful demonstration of a passively Q-switched S-band TFFL using an MWCNT-based SA.
060.0060 Fiber optics and optical communications 060.2430 Fibers, single-mode 060.4370 Nonlinear optics, fibers 140.3510 Lasers, fiber Chinese Optics Letters
2018, 16(1): 010609
Author Affiliations
Abstract
1 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
2 Department of Physics, Tsinghua University, Beijing 100084, China
3 SKA South Africa, Blend on Baker, Rosebank 2196, Johannesburg, South Africa
4 Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics & Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
In order to make the fiber-based frequency synchronization system suitable for the use of large-scale scientific and engineering projects in which the ambient temperature of the fiber links change dramatically, we design a non-harmonic frequency dissemination system immune to strong temperature fluctuation. After the lab tests, in which the ambient temperature of the fiber fluctuates 40°C/day and 20°C/h, respectively, the relative frequency stabilities of this system reaches 4.0 × 10 14/s and 3.0 × 10 16/104 s. It is demonstrated that the proposed non-harmonic scheme shows a strong robustness to complicated working environment with strong temperature fluctuation.
060.0060 Fiber optics and optical communications Chinese Optics Letters
2018, 16(1): 010605
重庆大学光电工程学院光电技术及系统教育部重点实验室, 重庆 400044
采用化学腐蚀法制备锥形光纤,采用溶液化学沉积法将银纳米颗粒修饰到锥形光纤端面,形成光纤表面增强拉曼散射(SERS)探针。改变反应温度、沉积时间、硝酸银溶液浓度等关键参数,优化了光纤SERS探针的制备工艺。以R6G为探针分子,对不同工艺条件制备的光纤SERS探针进行拉曼测试实验。结果表明:在室温下,当沉积时间为120 s、硝酸银溶液浓度为0.1 mol/L时,最优的增强因子约为10
10,此时光纤SERS探针的拉曼检测性能最好。对应10组样品的银纳米颗粒的直径和面积覆盖率,利用FDTD Solutions进行仿真建模分析,计算得到了拉曼增强因子理论值为10
7~10
8。
光谱学 光纤光学与光通信 表面增强拉曼散射 锥形光纤SERS探针 银纳米颗粒
Author Affiliations
Abstract
1 School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100191, China
2 International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
A novel slotted optical microdisk resonator, which significantly enhances light–matter interaction and provides a promising approach for increasing the sensitivity of sensors, is theoretically and numerically investigated. In this slotted resonator, the mode splitting is generated due to reflection of the slot. Remarkably, effects of the slot width and angular position on the mode splitting are mainly studied. The results reveal that the mode splitting is a second function of the slot width, and the maximum mode splitting induced by the slot deformation is achieved with 2.7853×109 Hz/nm. Therefore, the slotted resonator is an excellent candidate for pressure and force sensing. Besides, the influence of the slot angular position on the mode splitting is a cosine curve with the highest sensitivity of 1.23×1011 Hz/deg ; thus, the optical characteristic demonstrates that the slotted resonator can be used for inertial measurements.
Resonators Optical devices Fiber optics components Fiber optics Fiber optics and optical communications Photonics Research
2017, 5(3): 03000194
Author Affiliations
Abstract
1 Key Laboratory of Terahertz Solid State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
2 Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot and CNRS, UMR 7162, 10 rue A. Domont et L. Duquet, Paris 75205, France
3 e-mail: jccao@mail.sim.ac.cn
We demonstrate the electrical beat note analysis and radio frequency (RF) injection locking of a continuous wave (cw) terahertz quantum cascade laser (QCL) emitting around 3 THz (～100 μm). In free running the beat note frequency of the QCL shows a shift of ～180 MHz with increasing drive current. The beat note, modulation response, injection pulling, and terahertz emission spectral characteristics in the different current regimes I, II, and III are investigated. The results show that in the current regime I close to the laser threshold we obtain a narrower beat note and flat response to the RF modulation at the cavity round trip frequency. The pulling effect and spectral modulation measurements verify that in the current regime I the RF injection locking is more efficient and a robust tool to modulate the mode number and mode frequency of terahertz QCLs.
140.0140 Lasers and laser optics 040.0040 Detectors 350.0350 Other areas of optics 060.0060 Fiber optics and optical communications Chinese Optics Letters
2017, 15(1): 011404
