采用 PGC 零差检测方案的 Mach-zehnder 光纤干涉仪动态范围分析

Dynamic Range Analysis of Mach-zehnder Fiber Optic Interferometer Using PGC Homodyne Detection Scheme

介绍了在小相移及大相移不同工作情况下，Ｍａｃｈ－Ｚｅｈｎｄｅｒ光纤干涉仪可能达到的动态范围和限制动态范围增加的因素．着重分析了在采用相位产生载波（ＰＧＣ）的调制解调技术时，限制系统动态范围上限的主要因素．特别指出，待检测信号幅度越大，要求系统带宽越宽．文中揭示了载波和低通滤波器截止特性与待检测信号的幅度频率积的相互关联性及其对干涉仪动态范围上限的影响，得到的有关研究结论与实验结果符合的很好，可以作为双光束光纤干涉仪ＰＧＣ零差检测系统的设计与应用的理论依据和参考．

An analysis of achievable maximum dynamic range for the Mach-Zehnder fiber optic interferometer,working in small and large phase shift situations separately,is presented.The factors limiting the increase of the dynamic range are also given.The analysis puts an emphasis on the key factor-the upper limitation of the dynamic range,when a phase generated carrier (PGC) modulation-demodulation technique is used.The results of the analysis show that the larger the amplitude of the signal to be measured is ,the wider the needed frequency bandwidth of the system is ,the upper limitation of the dynamic range is affected by the frequency of the carrier,the cut-off frequency of the low pass filters,and product of the amplitude and the frequency of the signal to be measured.These conclusions are verified by the experimental results,and may be used as the basis and reference for the design and applications of double-beam fiber optic interferometers with PGC homodyne detection scheme.