A fiber micro-vibration sensor based on single-mode fiber ring laser

A new micro-vibration sensor based on single-mode fiber ring laser is put forward. The Mach-Zehnder interferometric （MZI） detection technique is presented for interrogating laser frequency shift due to the measurand （piezoelectric transducer （PZT） is used to simulate the micro-vibration） induced laser cavity strain from both single- and multi-mode lasers. In the experiment, compared with multi-mode laser sensors, the single-mode laser sensor is proved to be a sensor with high resolution. When the PZT is driven by the analog signal （0.03 rad near 2 kHz）, the signal-to-noise ratio （SNR） of output signal from the single-mode laser sensor is close to 55 dB and the sensitivity of the sensor is about 5 ×10^-5 rad/Hz1/2.     

激光多普勒微振动信号的直接强度解调

在传统的激光多普勒测振方法中,频移信号的检测通常需要具有比较复杂的频率或相位解调系统。从激光多普勒频移和干涉理论出发,提出了一种测量振幅小于纳米量级的方法———直接强度解调法。分析了直接强度解调法的适用范围。实验中利用了迈克尔逊干涉仪结构,采用了直接强度解调的方法。对振幅约为1nm的振动信号来说,其信噪比为23dB。     

光纤激光器的发展现状

由于在光通信、光数据存储、传感技术、医学等领域的广泛应用,近几年来光纤激光器发展十分迅速.本文简要介绍了光纤激光器的工作原理及特性,并对目前多种光纤激光器作了较为详细的分类;同时介绍了近几年国内外对于光纤激光器的研究方向及其目前的热点是高功率光纤激光器、窄线宽可调谐光纤激光器和超短脉冲光纤激光器;最后指出光纤激光器向高功率、多波长、窄线宽发展的趋势。     

宽带宽与新波段光纤放大器进展

宽带、调整、长距离和智能化是目前光纤通信系统发展的趋势所在，迅速膨胀的信息服务量使宽带成为最迫切的需求，新波段与长增益带宽光纤放大器的研究炙手可热，本文阐述了近期各波段光纤放大器以及拉曼放大器的进展，并揭示了光纤放大器向短波段和混合型发展的趋势。     

Design of 20 mm~200 mm zoom objective lens for polarization imaging system北大核心CSCD

The zoom objective lens is an important part of the polarization imaging system. At present, the zoom objective lens on the market is relatively expensive due to the use of more aspheric surfaces. In order to reduce the processing cost of the polarization imaging system zoom objective lens, a 20 mm~200 mm zoom objective lens for polarization imaging system was designed. By using positive group compensation method and Zemax to optimize the zoom system, the final system used only 7 spherical lenses to achieve good image quality. The modulation transfer function (MTF) is greater than 0.3 at 120 lp/mm, the distortion is less than 4%, and the cam curve of the system is smooth without breakpoints. The system tolerance analysis results show that the tolerance range is set as follows: the aperture tolerance of the lens surface is 2, the thickness tolerance of the lens or air center is ±0.02 mm, the inclination tolerance of the lens surface center is ±0.025°, the lens assembly and adjustment tolerance is ± 0.025 mm, and the lens refractive index deviation is 0.002. The tolerance setting conforms to the component processing and system assembly and adjustment process, which has a certain reference value to reduce the cost of polarization imaging system. © 2022 Editorial office of Journal of Applied Optics. All rights reserved.     

一种基于套嵌光纤光栅的高灵敏度光纤电流传感器

提出了一种基于套嵌光纤光栅的光纤电流传感器,该传感器使用了二次曝光法制作的长周期光栅结构和布拉格光栅结构套嵌的光纤光栅作为传感元件,通过直接在光栅表面制作镍铁合金作为加热电极层,当电流通过时对光栅区域加热引起光栅光谱中心波长漂移,实现了高灵敏度的电流测量。实验结果表明,这种光纤电流传感器的电流响应灵敏度达到7.2×10-2nm/mA,且具有结构简单、体积小等优点,在高灵敏度的光纤电流检测领域具有广泛应用价值。     

基于偏振模干涉的光纤光栅动态应变解调系统

基于保偏光纤中正交偏振模干涉,提出了一种简单、新颖的光纤光栅动态应变解调系统,并且通过实验证实了该方案的可行性。该解调系统光学核心部分仅由一段带有反射镜的高双折射光纤和一个光纤起偏器构成。实验中动态应变解调分辨率达到了 ,频率范围为0.1Hz~7.9kHz微纳振动幅度信号获得了保真拾取。实验表明,该系统适合宽频率范围、微纳幅度的动态应变检测,为光纤光栅传感提供了一种简单、经济、适用范围更广的解调方案。     

宽带宽与新波段光纤放大器进展

宽带、高速、长距离和智能化是目前光纤通信系统发展的趋势所在。迅速膨胀的信息服务量使宽带成为最迫切的需求,新波段与长增益带宽光纤放大器的研究炙手可热。本文阐述了近期各波段光纤放大器以及拉曼放大器的进展,并揭示了光纤放大器向短波段和混合型发展的趋势。     

低噪声光纤激光器的实验研究

光传感和光通信领域的迅速发展迫切需要相位噪声和强度噪声都很低的激光光源,为满足这一需求,设计出一种新型低噪声光纤激光器。激光器采用复合腔结构,以掺铒光纤作为工作物质,通过在未被抽运的掺铒光纤中形成的瞬态自写入光纤光栅的窄带滤波特性进行选模和压窄线宽,产生稳定的单频激光输出;经过光路改进,激光输出光谱信噪比优于62 dB;利用光电负反馈电路,弛豫振荡峰下降了约25 dB,低频段强度噪声也大为改善,有效地抑制了光源的强度噪声。激光器的输出光功率大于1 dBm,线宽小于1 kHz,边模抑制比超过50 dB。优异的低噪声特性使得该激光器在光传感和光通信领域具有重要的应用价值。     

大气湍流对激光外差探测的影响

研究了大气湍流情况下到达角起伏对激光外差探测系统干涉效率的影响.在实验室模拟大气湍流的条件下,分析检测了激光外差探测系统的干涉效率与信噪比,为提高激光外差探测系统的实用性能积累了一定的理论和实验数据.