【作者】 郭峻；

【导师】 胡泓； 何永红；

【作者基本信息】 哈尔滨工业大学 ， 工程硕士（专业学位）， 2016， 硕士

【摘要】 实时测量应力、应变,在工程应用中是非常重要的。光纤布拉格光栅(FBG)作为应力传感器具有高灵敏度、抗电磁干扰、寿命长等特点,借助于光通信的高可靠性器件,能够大大的降低传感成本。FBG传感器通过复用的方法,可以形成传感网络,从而大大降低传感器布线的难度。本文首先研究了基于可调谐激光器的FBG传感测量与复用方式,实现了啁啾信号作为调制信号,利用其时间相关特性实现FBG传感器的时分复用。通过设置啁啾函数的初始与最终频率,从而实现FBG间隔为10ns的时分复用。该方案能够降低解调设备对于高速ADC的要求,能够大大降低解调仪的成本,并提高了FBG的复用个数。为了进一步提高传感性能,本文研究了一种基于波长可精密调谐的分布式布拉格反射(DBR)激光器。DBR激光器应用于FBG传感,具有信噪比高、能量利用率高、波长定位精度高等优点。但是普通DBR激光器在波长的光谱调谐范围比较窄,不能适用于FBG传感的需求。而其他类型激光器虽然范围较大,但定位精度低,也不能满足传感需求。本文研究了用于光纤通信系统的DS-DBR激光器,该激光器仅能在光通信标准要求的波长之间调谐,不符合FBG传感需求。根据其调谐原理,提出了波长连续可调调谐的方案DS-DBR激光器,通过对激光器驱动器的重新设计,实现了0.1pm精度连续可调的激光输出,50nm光谱范围调谐速度可达1MHz。基于数字信号处理器(DSP)技术和高速可调谐激光器,本文实现了FBG传感在应力测量中的演示,并对传感系统进行了实验测试。本文首先测试了单FBG传感系统的直接扫描实验,获得了较高的传感精度,实验中,精度可达0.1pm。然后采用啁啾时分复用系统,分别测试了其静态稳定性和连续测量中的传感性能。测量精度有所降低,为4pm。本文分析为不同位置FBG信号间的串扰噪声引起了测量精度的降低。更多还原

【Abstract】 Fiber Bragg Gratings(FBG)can be sensors with high sensitivity and long life due to the high reliability provided by the optical communication industry.FBG sensors make sensing network by multiplexing to fulfill a semi-distributed sensing,which make the setup of sensors easy.Firstly,the multiplexing of FBG sensors is analyzed according to the industrial application,which focuses on the time division multiplexing technique.The chirped sine signals are applied to realize a compact time division multiplexing,which is based on the characters of auto correlation function of signal.This method only requires a slow sampling rate of ADC to separate different multiplexed sensors.Accordingly,the interval of time can be shorten.Besides,a high precision FBG sensing network need a wavelength tunable laser with high performances,such as high wavelength precision,fast tuning speed and wide tuning range.Accordingly,Distributed Bragg Reflector(DBR)laser is a good candidate for FBG sensing but with small scanning range.Here,a new type DBR laser,Digital Supermode DBR laser(DS-DBR)is investigated,which contains a chirped Bragg gratings as one of the reflector.DS-DBR laser is designed for the long haul optical communication that required the wavelength is tuned among some specific value defined by ITU,which is separated by 0.4nm.According to the requirement of FBG sensing,the tuning principle of DS-DBR is researched for high speed tuning and continuous tuning.The rear grating and phase domain are investigated to evaluate their performance.It is found that the laser can be tuned continuously with precision 0.1pm by modifying the phase driver circuit of laser.A current driver is designed accordingly to drive DS-DBR laser to tune continuously with a span of 50 nm at the rate of 1MHz.Further,we demonstrate the FBG sensing based on the continuous DS-DBR laser and DSP technology.A single FBG sensing is firstly demonstrated,which gets a high precision with 0.1pm.Next,a time division multiplexed FBG sensing system,coded by the chirped sine wave,is demonstrated which gives a short time interval as 10 meters in distance.However,The sensing system is demonstrated on the static condition and on the sensing of temperature and strain,whose measurement precision is low as 4pm due the crosstalk between the FBGs.更多还原