光时域反射仪的激光驱动电源设计与光电探测实现

发布时间：2018-11-24 16:18

【摘要】：随着光通信的蓬勃发展,光纤通信技术广泛应用于电信、电力、广播等领域,对整个信息产业产生了深远影响,光纤已成为当前最有前景的传输媒介。与此同时,光纤测试技术在光纤生产、现场铺设与后期维护等工程领域中得到广泛应用。光时域反射仪(Optical Time Domain Reflectometer),又称背向散射仪,是一种用于表征光纤链路物理特性的精密光学测试仪器,主要用于测试光纤链路长度,精确定位断点事件,计算光纤损耗,并提供与长度有关的衰减细节。光纤链路中待测光纤的测量长度范围和测量精度,取决于OTDR的激光出纤功率和光脉宽。因此,需要设计合适的激光脉冲驱动电源及配套的控制和探测系统,研究激光出纤功率和脉宽对测量长度和测量精度的影响,从而获得能满足不同光纤链路测量需求的OTDR系统解决方案。文章在具体描述了光时域反射仪的工作机理以及影响其主要性能的关键参数的基础上,提出以设计能提供大功率、窄脉冲电流信号的激光驱动电源作为提高OTDR性能的主要手段。在掌握半导体激光驱动原理的基础上,经过细致地比较与方案论证,提出以MOSFET作为激光脉冲驱动电源的开关器件,以能量储存法作为窄脉冲产生机制的脉冲电源设计方案。设计实现基于FPGA的触发脉冲信号,并通过Multisim 11对系统硬件电路仿真优化,实现激光脉冲驱动大功率、窄脉宽输出。以雪崩二极管作为光电探测系统关键响应转换器件验证驱动电源性能,并完成光纤测距。最终成功研制出一套基于纳秒脉冲激光和对应光电探测系统的OTDR系统,并进行了实际测试。测试和研究结果显示:所研制的脉冲激光电源能输出的最小脉宽为33 ns,最小输出峰值电流为1 A,且峰值电流及频率大小可调。大电流窄脉宽驱动电源信号输出可极大地增强光时域反射仪的动态范围以及分辨率。探测器分时调控测量技术可以极大地提高系统的测量精度和信噪比。本文设计的脉冲激光驱动电源与光电探测系统,不仅可以用于开发具有各种技术参数的OTDR设备,也可以用于常规的半导体激光器系统。其应用亦可从单纯的光纤测试系统推广至涵盖军用和民用的整个激光测距领域。因而本论文的研究成果具有重要的应用价值和社会价值。
[Abstract]:With the rapid development of optical communication, optical fiber communication technology is widely used in telecommunications, power, broadcasting and other fields, which has a profound impact on the entire information industry. Optical fiber has become the most promising transmission medium. At the same time, optical fiber testing technology has been widely used in optical fiber production, site laying and later maintenance and other engineering fields. Optical time domain reflectometer (Optical Time Domain Reflectometer), also called backscattering instrument, is a precise optical testing instrument used to characterize the physical characteristics of optical fiber links. It is mainly used to measure the length of optical fiber links, locate breakpoint events accurately, and calculate fiber losses. Details of attenuation related to length are also provided. The measurement length range and measurement accuracy of the fiber to be measured in the fiber link depends on the laser output power and the optical pulse width of the OTDR. Therefore, it is necessary to design a suitable laser pulse driving power supply and a complete control and detection system to study the influence of laser output power and pulse width on the length and accuracy of the measurement. Thus, the OTDR system solution which can meet the measurement requirements of different fiber links is obtained. Based on the detailed description of the working mechanism of the optical time domain reflectometer and the key parameters affecting its main performance, this paper proposes to design a laser drive power supply which can provide high power and narrow pulse current signals as the main means to improve the performance of OTDR. On the basis of mastering the principle of semiconductor laser drive, after careful comparison and demonstration, a design scheme of pulse power supply with MOSFET as switching device and energy storage as the mechanism of narrow pulse generation is put forward. The trigger pulse signal based on FPGA is designed and realized, and the system hardware circuit is simulated and optimized by Multisim 11 to realize the laser pulse driving high power and narrow pulse width output. The Avalanche diode is used as the key response converter of the photoelectric detection system to verify the performance of the driving power supply and to complete the optical fiber ranging. Finally, a OTDR system based on nanosecond pulse laser and corresponding photoelectric detection system is developed and tested. The experimental results show that the minimum pulse width of the pulse laser power supply is 33 ns, and the minimum output peak current is 1 A, and the peak current and frequency can be adjusted. The dynamic range and resolution of the optical time domain reflectometer can be greatly enhanced by the output of the high current and narrow pulse width driving power supply. The measurement accuracy and signal-to-noise ratio of the system can be greatly improved by the detector time-sharing control measurement technique. The pulse laser drive power supply and photoelectric detection system designed in this paper can not only be used to develop OTDR equipment with various technical parameters, but also can be used in conventional semiconductor laser systems. Its application can also be extended from a simple optical fiber testing system to the whole laser ranging field covering both military and civil applications. Therefore, the research results of this paper have important application value and social value.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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