【作者】 戴高宇；

【导师】 樊昕昱；

【作者基本信息】 上海交通大学 ， 电子科学与技术， 2019， 硕士

【摘要】 拉曼分布式光纤传感器(RDTS)是一种基于光纤中拉曼散射效应的温度传感器,具有动态范围高、受机械应变影响小等优点。作为光纤传感技术的一个分支,在石油、天然气管道的防火监测,发电站和输电线的温度控制,以及大坝的渗漏检测方面有着十分广泛的应用。RDTS性能提升一直是研究者们的主要关注点,针对不同的工业应用场景,很多性能改善方案被提出。其中,在RDTS中使用脉冲编码技术可以在保持空间分辨率的同时提高系统信噪比,因此受到广泛关注,但是脉冲编码技术在长距离情况下的应用需要克服很多局限性,因此对基于编码技术的RDTS进行研究,具有很大的应用前景和学术价值。本课题首先对单脉冲输入情况下的RDTS进行了理论分析和数学建模,并对其进行了软件仿真,在此基础上,分析了Simplex编码对RDTS性能提升的原理,并建立了相应的仿真模型。基于仿真基础,针对脉冲编码序列经过掺铒光纤放大器(EDFA)放大会产生瞬态效应这一局限性,从成本降低和性能提升的角度,提出了基于脉冲编码的新型双光源RDTS结构,并进行了光路及电路系统的搭建。相对于传统RDTS结构,该方案具有成本低,传感距离长的优势:本课题中使用两个分布反馈式(DFB)激光二极管作为光源,采用新型的直接调制方案避免了调制器和驱动器的使用,降低了系统成本。同时,通过两个光源之间的配合消除长距离情况下EDFA对编码信号进行放大时产生的瞬态效应,使系统能够同时结合EDFA放大和Simplex编码两种提升系统性能的机制,又有别于传统非归零(NRZ)Simplex编码。该系统中采用归零(RZ)Simplex编码,进一步提高了入射脉冲峰值功率实现了长达的传感距离。更多还原

【Abstract】 RDTS(Raman distributed temperature sensor)is a kind of temperature sensor based on Raman effect in optical fiber.For RDTS,there are some distinguished advantages such as high dynamic range,less sensitivity to strain.As a branch of optical fiber sensing technology,RDTS is widely used in many important industrial applications such as fire detecting in oil and gas pipeline,temperature controlling in power plant and power transmission line and leakage detecting in embankment dams.For these applications,the performance of RDTS is widely attracting attentions.Besides,many methods and system structure for improving RDTS system performance are developed according to different industrial application scenes.Among these techniques,pulse coding technique has been paying more attentions since it is able to increase the system SNR(signal-to-noise ratio)while keeping the same spatial resolution.However,for the application of coding technique in long-range system,there are still many problems to solve.In a word,we can find great potentials of applications and theoretical significance by conducting research on this technique.In this paper,first,the theoretical analysis and mathematical modeling of RDTS under single pulse input are carried out,and simulations are performed by using software.Based on this,the principle of improving RDTS performance by Simplex coding is analyzed,and the corresponding simulation model is established.According to the simulation above,considering the limitation that the pulse code sequence is amplified by EDFA(erbium-doped fiber amplifier),the new dual-source RDTS configuration based on pulse coding is proposed and the optical/electrical system is established following the perspective of cost-effectiveness.The construction and performance measurement,compared with the traditional RDTS system,shows the advantages of low cost and long sensing distance.In this paper,two DFB(distributed feedback)laser diodes are used as the light source.The new direct modulation scheme avoids the use of modulators and drivers and thus reduces system cost.At the same time,through the cooperation between the two light sources,the transient effect generated by the EDFA in amplifying the encoded signal in the long distance is eliminated,so that the system can combine the EDFA amplification and the Simplex coding to improve the performance.Different from traditional NRZ(non-return-to-zero)Simplex encoding,the system uses RZ(return-tozero)Simplex encoding to further increase the peak power of the incident pulse to achieve a sensing distance of up to 56 km.更多还原