酸溶法光纤传像束透光性能的研究

为了解决酸溶法光纤传像束光透过率较低(不足40%)的问题,通过在传像束的两个端面加镀增透膜,其透过率有了明显的提高,达到了7.38%,拓宽了传像束的应用领域。介绍了膜系设计、镀膜材料的选择以及真空速率的控制对镀膜效果的影响。对影响酸溶法光纤传像束透光性能的各种主要因素进行了分析。     

光纤法布里-珀罗传感器光纤端面反射率优化

讨论了反射光纤端面反射率对（F-P）传感器输出信号质量的影响,指出反射光纤端面反射率的提高可以克服光在F-P腔内损耗的影响,且对应传感器腔长有和其匹配的最优反射率.为了使传感器在其工作腔长范围内的输出信号整体上具有尽可能好的信号质量,采用最小均方误差法确定了反射光纤端面的最优反射率.仿真证明了采用最优反射率时的信号质量优于采用非最优反射率时的信号质量.     

基于飞秒激光的光纤切割加工工艺研究

为了得到理想的光纤切割断面,利用飞秒激光对石英光纤材料进行切割微加工实验。研究激光功率、脉冲频率、扫描速度等加工参数与光纤切割断面质量间的关系,以寻求最理想的加工参数。最后在可调倾角光纤夹具的辅助下,很好地弥补加工过程中产生的端面倾斜角,得到垂直度高达89.56°的光纤切割断面。     

光纤连接器端面几何参量自动测量仪

报道了一种高精度测量光纤连接器端面几何参量的自动测量仪。叙述了光纤连接器的端面几何参量的测量原理。由光纤连接器端面形貌和纤芯中心坐标,可以高精度得到曲率半径、顶点偏移量、端面倾斜角和光纤高度等影响连接器性能的关键端面几何参量。该仪器体积小,自动化程度高,用户界面友好,使用方便,可测量物理接触、角度式物理接触等类型的光纤连接器端面几何参量。实际测量证明,该测量仪有很好的重复测量精度。该测量仪与美国Dorc公司ZX-1 mini PMS测量仪和Norland公司NC3000测量仪相比,测量精度水平相当。该仪器样机已通过华东国家计量测试中心的测试。     

光纤端面反射对高功率光纤放大器特性的影响

 从光纤端面研抛工艺的技术特点出发,计算了端面倾角和反射率的关系,估算了斜面研抛后端面反射率的大小。在掺Yb³⁺双包层光纤放大器理论模型的基础上,数值模拟了常规研抛角度误差造成的端面反射率对放大器输出特性的影响。计算结果表明：端面反射导致系统内出现严重放大的自发辐射和自激现象,减小光纤两个端面的反射率是最有效的抑制方法,同时,增大入射信号激光功率也可以抑制自激,提高输出信号光功率和信噪比。     

光纤端面偏移对光纤F-P可调谐滤波器性能影响

在光纤F-P可调谐滤波器进行滤波调谐的过程中经常会出现光纤端面偏移的问题,从而导致其滤波性能下降。通过ZEMAX光学仿真软件对其光纤F-P腔部分进行仿真,模拟两光纤端面发生径向偏移和产生倾角时的情况,通过对仿真结果分析得出当发生径向偏移时将会导致光纤F-P可调谐滤波器的峰值透过率减小,插入损耗增加;在产生倾角时将会导致光纤F-P可调谐滤波器的3dB带宽增加以及阻带抑制能力减弱,而当倾角大于0.005°时其滤波性能将会发生明显衰减。     

光纤端面角度对光纤F-P传感器干涉光谱影响

光纤法布里-珀罗(F-P)传感器反射光谱的对比度直接影响解调精度,利用模式耦合理论分析了端面倾斜角度对F-P传感器的反射光谱对比度以及信号强度的影响。通过理论和试验证明:随着光纤端面倾斜角度的增大,反射光谱对比度迅速下降,当角度达到5°以上时,反射光谱无法解调。     

微纳光纤端面反射特性的实验测量方法

微纳光纤的端面反射特性是影响其传输特性及实际应用的重要因素之一. 本文提出了一种基于光环形器的微纳光纤端面反射特性测量方法. 该方法克服了3 dB耦合器直接测量法的不足, 通过引入气凝胶固定和功率补偿, 可有效地消除微纳光纤尾纤飘摆、光源输出不稳定及其内部损耗等不利因素, 从而提高测量的准确度. 采用该方案实验测量了微纳光纤的端面反射率及其与 光纤直径和传输波长间的关系. 实验结果与数值模拟结果相符, 表明该方法可有效地用于微纳光纤端面反射率测量及其与各特性参数之间关系的分析, 这对于微纳光纤激光器、放大器、耦合器及滤波器等光学微型器件的设计制作具有重要意义. 关键词： 光纤光学 微纳光纤 端面反射 光环形器     

光纤端面Nd:YAG激光诱导损伤分析

采用Nd:YAG激光对全石英多模光纤进行激光诱导损伤实验.结果全部为光纤端面损伤,主要是由光纤端面的杂质缺陷引起的.通过对激光损伤形貌的分析,明确光纤端面损伤机理.采用Matlab对光纤损伤端面进行图像处理,获得光纤端面损伤点的大小、出现频率和位置分布的统计特性.通过分析发现,光纤端面损伤点位置分布服从一定的规律,光纤前端面和后端面不同;光纤端面不同大小损伤点出现频率服从高斯分布;注入激光特性参数决定光纤前端面损伤特性,光纤传能特性以及光纤端面质量决定其后端面损伤特性.     

光纤表面粗糙度检测系统的研究

基于传光型光纤传感器,利用反射式光强调制原理,设计了一套材料表面粗糙度的检测系统。整个系统包含光源、Y型光纤束、反射调节控制装置和数据采集部分,采用单片机作为控制系统。分析了光纤束端面与检测样品距离的变化对检测结果的影响。     

真空条件下激光诱导光纤损伤特性研究

实验研究并分析了调Q Nd:YAG 脉冲激光诱导光纤损伤特性.设计了在真空条件下全石英光纤传输1064 nm 脉冲激光实验.通过将激光注入光纤端面气压降低到10—100 Pa, 光纤端面击穿阈值提高到大气环境下的185 倍.结合光纤端面损伤形貌分析可知,光纤端面损伤主要是由于激光驻波场和烧蚀共同作用的结果,光纤端面或内部大量的缺陷降低了光纤抗激光损伤的能力.在真空条件下由于光纤端面光学击穿阈值的提高,激光诱导光纤损伤特性又表现出了另外一种损伤模式——光纤初始输入段损伤.它发生在光纤输入段附 关键词： 激光损伤 光束传输 真空 石英光纤     

Multifiber optical catheter with bending control of distal end: Applications of Raman biospectroscopy

This work demonstrates a multifiber optical catheter with bending control of the distal end, whose main use is to collect Raman signal for biospectroscopy. Also, a method for fiber background subtraction is presented, allowing removal of fiber emission peaks from gross Raman spectrum. The fiber optic catheter with seven fiber optics wrapped up in a resin and a biocompatible flexible teflon tube has been modified to incorporate a mechanical device with gauntlet, which allows bending of the distal extremity to access a desired location obeying the anatomy of the organ. The mechanical device (gauntlet) was built halfway from the catheter proximal excitation tip, allowing the bending of the distal end of about 38 mm diameter. Dispersive Raman spectra at 785 nm excitation wavelength from samples were measured without and with bending (from 120 mm decreasing to 14 mm) of the distal end of the catheter. An optical catheter without the gauntlet was used as a reference. Results demonstrated that both catheters (with bending mechanism and standard one) had about the same Raman signal when the device was bent semicircularly to 38 mm diameter (bending limit for the mechanism), with negligible implication to the Raman signal-to-noise relation (SNR) from sample. When both catheters were bent in a full turn, the Raman signal decreased to about 40% when bending reached 14 mm diameter, mainly due to losses introduced by changes in the fiber total internal reflection. The background removal was efficient, with minimum residual from fiber peaks. This optical catherer could be very useful in laser diagnosis and clinical applications, introducing a way to control the fiber tip position and angle on the tissue or organ. Published in Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 97–102, January–February, 2007.     

混沌-脉冲混合信号光时域反射仪

研制了一种混沌-脉冲混合信号光时域反射仪,其工作原理是通过连续混沌光与离散脉冲光分别对光纤中的菲涅尔反射与后向瑞利散射进行高精度测量,将2次测量结果进行线性叠加得到光纤故障测量曲线,该仪器解决了传统混沌光时域反射仪无法测量光纤损耗事件的问题。实验中利用G.652.B单模光纤作为被测对象,对该仪器进行了实际测试,测试结果表明:所研制的混沌-脉冲混合信号光时域反射仪在104 km测量范围内实现了与距离无关的35 cm空间分辨率测量,对光纤损耗事件也有良好的检测效果。     

Stimulated Brillouin scattering as the referencing mechanism of an optical fibre intensity sensor

An optical fibre intensity sensor referenced by stimulated Brillouin scattering is presented. The optical sensor uses Fresnel reflection signal at the sensor fibre end and employs an adequate relationship between Brillouin and Rayleigh scattering and Fresnel reflection to have a referenced optical fibre intensity sensor addressed in reflection.     

Pigtailing the high-Q microsphere cavity: a simple fiber coupler for optical whispering-gallery modes

We demonstrate a simple method for efficient coupling of standard single-mode optical fibers to a high- Q optical microsphere cavity. Phase-matched excitation of whispering-gallery modes is provided by an angle-polished fiber tip in which the core-guided wave undergoes total internal reflection. In the experimental setup, which included a microsphere with both an input and an output coupler, the total fiber-to-fiber transmission at resonance reached 23% (total insertion loss, 6.3 dB), with loaded quality factor Q>/=3x10(7) and unloaded Q approximately 1.2x10(8) at 1550 nm. A simple pigtailing method for microspheres permits their wider use in fiber optics and photonics devices.     

球形光纤端面效应及其应用

本文介绍了球形光纤端面的制作方法,采用射线理论和等效透镜法分析了圆球形端面多模光纤的端面效应,并给出了两个不同端面多模光纤之间耦合的实验结果。结果表明：圆球形端面光纤具有聚光特性,与平端面相比,使用圆球形端面光纤不仅可以提高光器件之间的耦合效率,而且增大了它们之间的耦合距离,利于光路调试;可广泛应用于光源与光纤、光纤与光纤、光纤与探测器之间的耦合。     

Method for measurement of fusion-splicing-induced reflection in a photonic bandgap fiber-optical gyro

We propose a method for the real-time measurement of the reflection at both splicing points between a photonic bandgap fiber coil and conventional fiber during the process of fusion splicing in a photonic bandgap fiber optical gyroscope(PBFOG), using the interference among the secondary waves, which arise from the fusion splicing points and the mirror face produced by intentionally cutting the bear end of the coupler. The method is theoretically proven and experimentally verified in a practical PBFOG, and it is significant for inline examination of the fusion splicing quality and evaluation of the PBFOG performance.     

Reflection-scanning near-field optical microscopy and spectroscopy of opaque samples

Opaque samples are imaged by Scanning Nearfield Optical Microscopy (SNOM) in reflection mode: A quartz glass fiber tip is used both to illuminate the sample and to collect light locally reflected from or emitted by the surface. The collected light is coupled out by a 2×2 fiber coupler and fed into a grating spectrometer for spectral analysis at each sampled point. The tip-sample distance is controlled by a shear-force feedback system. The simultaneous measurement of topography and optical signals allows an assessment of imaging artifacts, notably topography-induced intensity changes. It is demonstrated that an optical reflectance contrast not induced by topographic interference can be found on suitable samples. Local spectral analysis is shown in images of a photoluminescent layer.     

An experimental investigation of the optical switching characteristics using an optical Sagnac interferometer incorporating one and two ring resonators

We present the use of a fiber optic Sagnac interferometer incorporating one and two fiber optic ring resonators to characterize experimentally the optical switching behaviors. These prototypes were formed by the Sagnac interferometer and serially connected to the ring resonators. The input optical signal was launched via one end of the interferometer, where the polarization control was employed to obtain the maximum optical transmission power. Results obtained have shown that the increasing in switching time (i.e. narrower spectral width) and power can be achieved.