【作者】 梁迅；

【导师】 胡永明；

【作者基本信息】 国防科学技术大学 ， 光学工程， 2008， 博士

【摘要】 光纤水听器系统逐渐走向大规模阵列应用阶段,其噪声问题作为系统的关键技术问题,成为提升系统性能的瓶颈,本文对光纤水听器系统噪声问题进行了深入的分析研究,解决了一些关键技术问题,将推动光纤水听器技术的进步。在大规模水听器系统基本方案的基础上,分析了系统各种噪声的来源,针对光频调制非平衡相干检测PGC解调方案的光纤水听器系统,建立了包含各种因素的相位噪声模型,揭示了各种噪声到系统最终相位信号输出的传递关系,为系统各种噪声分析奠定基础。对环形腔激光器的弛豫振荡进行了深入理论研究和试验测试,分析了弛豫振荡噪声对PGC解调的影响,提出了改变驱动功率来改变噪声峰位置,从而降低该噪声对系统噪声影响的方法,并通过改进激光器结构参数和研制具有弛豫振荡抑制功能的高性能驱动控制器,使弛豫振荡峰减小25dB以上,残余振荡小于3dB,大幅度降低了系统噪声。建立了非平衡干涉仪相位噪声的测试系统,结合大规模光纤水听器阵列的结构和探测基元的参数特性,探索通过补偿抑制相位噪声的具体措施,提出主动相位扰动自动参数获取的相位噪声抑制方法,有效抑制大相位噪声最高可达20dB以上,解决了大规模光纤水听器阵列相位噪声抑制的一大难题,提高了系统的抗环境干扰能力和探测性能。研究了激光器的跳模现象对系统的影响,通过对激光器参数的调整和跳模过程的测试,寻找被动抑制跳模的最佳结构参数,在一定程度上抑制跳模的发生和降低跳模频度,在静态下8小时跳模可降到5次以下。通过对PGC解调信号中跳模过程的分析,探讨了主动抑制跳模的可能控制参量和主动跳模抑制的可能性。通过电光偏振调制的研究,探讨光传输偏振噪声问题,提出了在时分复用PGC解调系统中同步调制采样抑制偏振起伏的有效方法。提出了高相干光传输杂散光相干噪声问题,给出了定量分析结果,为大规模光纤水听器系统设计和系统建造中光传输噪声的控制提供了一项依据。本论文的研究成果已在实际系统中得到应用。更多还原

【Abstract】 Fiber optic hydrophone systems are developing into large scale array applications. As the key technical problem of the system, noise problem is becoming a bottle neck to enhance the system performance. In this dissertation, noise problem of the fiber optic hydrophone system has been analyzed and some key technical problem has been solved, which will push forward the advancing of the fiber optic hydrophone technology.Based on the basic hydrophone system scheme, variant noise sources have been analyzed. For frequency modulated unbalanced coherent detecting Phase Generated Carrier (PGC) fiber optic hydrophone system, a phase noise model including variant noise factors has been established. The transfer function of different noise sources to the final phase output has been revealed, which makes the basis of the system noise analysis.The relaxation oscillation of the fiber ring laser has been studied theoretically and experimentally. The influence of the relaxation oscillation noise to the PGC scheme has been analyzed and a new method of changing pump power to change the noise peak frequency so that lower the noise influence has been proposed. Further more, by improving the laser structure parameter and developing a high performance pump driver which has the ability to suppress relaxation oscillation, the noise peak has been reduced by 25dB, the remaining noise less than 3dB.The system noise has been greatly reduced.A phase noise testing system based on unbalanced interferometer has been established. According to the structure of large scale fiber optic hydrophone array system and the sensor parameter character, realistic ways to suppress phase noise by means of compensation has been explored. A method of active disturbing and automate parameter obtaining to reduce the phase noise has been proposed. In the highest case, it can reduce the phase noise higher than 20dB, which greatly improves the performance and anti-disturbance ability of the system.The influence of the laser mode-hopping to the system has been studied. By adjusting the parameter of the laser in the test of the mode hopping, we can find the best parameter to reduce mode-hopping. As a result, the mode-hopping can be reduced to less than 5 times in 8 hours. By analyzing the PGC output signal when mode-hopping occurs, ways to actively reducing mode hopping has been studied.An effective method based on synchronizing modulation and sampling to reduce Polarization-Induced Fading (PIF) in Time Division Multiplexing (TDM) system By Electro-optic Modulation (EOM) has been studied. The noise caused by high coherent stray light has been discussed and quantitative results have been given, which provides a basis in controlling the light transmission noise in large scale fiber optic hydrophone system.All the research productions of this dissertation have been used in real fiber optic hydrophone systems.更多还原