提出并实现了一种用于微弱极低频信号探测的干涉式光纤传感器相位生成载波（PGC）解调方法。对PGC解调方法中微分交叉相乘(DCM)及反正切(Arctangent)两种相位抽取算法应用于极低频信号解调进行了理论分析和算法仿真，其结果表明，DCM式PGC算法解调极低频信号时，其结果中存在直流漂移，而Arctangent 式PGC算法的解调结果中不存在直流漂移问题。进而基于光纤干涉仪搭建了极低频光纤传感系统，并进行了两种PGC解调算法的对比实验，实验结果表明，Arctangent式PGC算法不存在DCM式PGC算法解调极低频信号时的直流漂移，且能够准确解调极低频信号，与理论分析的结论相符。最后采用Arctangent式PGC算法实现了极低频干涉式光纤传感系统，该系统达到的最低可探测信号频率为0.01 Hz，最小可探测信号为4×10－4 rad/Hz，动态范围为110 dB @ 1 Hz，线性相关系数为99.99 %。

A high resolution ultra low frequency phase generated carrier(PGC) demodulation technique for interferometric fiber sensors is proposed. The differential cross multiplication(DCM) algorithm and the Arctangent algorithm of PGC technique are analyzed theoretically and simulated by computer for ultra low frequency demodulation. And the results show that an unnecessary random direct current (DC) drift is induced in the recovered signal of DCM-PGC, but it doesn′t exit in that of Arctangent-PGC. To demonstrate the conclusion, an optical fiber interferometer-based ultra low frequency sensing system is set up, and the comparable experiments of DCM-PGC and Arctangent-PGC are carried out. The experimental results show that only Arctangent-PGC can be used for ultra low frequency demodulation, for it avoids the problem of DC drift as DCM-PGC. At last the ultra low frequency demodulation system is achieved by Arctangent-PGC, and the testing results show that the system has the lowest frequency of 0.01 Hz, a minimum detectable phase shift of 4×10－4 rad/Hz, a dynamic range of 110 dB @ 1 Hz and a linearity of 99.99 %.