大光斑离轴式光纤旋转连接器的耦合性能  

Coupling performance of large spot off-axis fiber optic rotary joint

作　　者：赵振刚[1,2] 王思飞 段绍锋 曹发松 刘爱莲 ZHAO Zhengang;WANG Sifei;DUAN Shaofeng;CAO Fasong;LIU Ailian(Faculty of Information Engineering and Automation,Kunming University of Science and Technology,Kunming 650500,China;Yunnan Key Laboratory of Green Energy,Electric Power Measurement Digitalization,Control and Protection,Kunming 650500,China)

机构地区：[1]昆明理工大学信息工程与自动化学院,云南昆明650500 [2]云南省绿色能源与数字电力量测及控保重点实验室,云南昆明650500

出　　处：《光学精密工程》2023年第10期1443-1453,共11页Optics and Precision Engineering

基　　金：云南省科技厅基础研究专项-重点项目资助(No.202101AS070096);云南省科技计划资助项目(No.202101AT070131)。

摘　　要：针对直接对准型离轴式光纤旋转连接器中自聚焦透镜准直器出射光斑小、光纤耦合损耗大和有效对准时间短的问题,本文提出了一种由双合透镜和热扩芯光纤构成的大光斑光纤准直器。基于出射光斑在相对旋转过程中重叠面积的周期性变化规律,分析了准直器间存在径向误差和角向误差时的耦合损耗变化。根据转子圆环和出射光斑尺寸得到耦合损耗为3 dB时的理论有效对准时间。为此搭建了光纤耦合实验平台测试其耦合性能及有效对准时间。实验结果表明,光纤准直器采用的单模光纤模场直径越大耦合损耗越低,其中模场直径为28μm时耦合损耗低至0.22 dB。在转速为60 r/min时,通过光电转化和函数拟合得到四种模场直径光纤准直器的有效对准时间。模场直径为17μm时最大有效对准时间为7.05 ms,与理论值7.1672 ms基本一致。最后应用光纤布拉格光栅传感实现无接触式传输光信号。这种设计为大光斑离轴式光纤旋转连接器的研究及其在光纤传感领域的应用提供了理论和技术支撑。To solve the problems of the small spot of graded-index lenses and the significant coupling loss and short effective alignment time of the current direct alignment-type off-axis fiber optic rotary joint,this study devised a large-spot fiber collimator made of a double-lens collimator and thermal expansion core fiber.Based on the periodic variation law of the overlapping area when the exit spot rotates relatively,the change in the coupling loss when there are radial and angular errors between the collimator was analyzed.The theoretical effective alignment time of the off-axis fiber optic rotary joint under a 3-dB coupling loss was calculated from the exit spot size of the rotor ring and the fiber collimator.An optical fiber coupling experimental platform was set up to test the coupling performance of the off-axis fiber optic rotary joint and measure the effective alignment time.The experimental results indicate that a larger mode field diameter(MFD)of the single-mode fiber used in the fiber collimator corresponds to a smaller coupling loss.In the test,a large MFD of 28μm yields the minimum loss of 0.22 dB.At a speed of 60 r/min,the effective alignment times of the four MFD fiber collimators were obtained via photoelectric conversion and function fitting.For the MFD of 17μm,the maximum effective alignment time is 7.05 ms,which is close to the theoretical value of 7.1672 ms.Finally,fiber Bragg grating sensing was applied to achieve contactless transmission of optical signals.This design provides theoretical and technical support for the large-spot offaxis fiber optic rotary joint and its application in optical fiber sensing.

关 键 词：离轴 光纤旋转连接器 双合透镜 热扩芯光纤 光纤耦合 

分 类 号：TN253[电子电信—物理电子学]