Sagnac光纤水听器锯齿波相位偏置技术

Fiber Optic Hydrophone Based on Sagnac Interferometer with Saw-Tooth Wave Phase Biasing Technique

提出了Sagnac光纤水听器锯齿波主动相位偏置方案,分析了锯齿波2π复位误差对系统性能的影响。采用频率为94.05kHz,复位电压为10.84V的锯齿波对信号进行调制,将系统偏置在π/2附近。为抑制2π复位误差的影响,采用与锯齿波同步的脉冲信号控制模/数(A/D)转换器定时采样,采样结果就是所需的声音信号。实验表明,该系统在10kHz频率响应处信号幅度平均值为0.067rad,方差为3.08×10-5rad,信号幅度相对变化仅为0.046%,系统相位偏置十分稳定。

A fiber optic hydrophone based on Sagnac interferometer with saw-tooth active phase biasing technique is proposed and demonstrated experimentally. The influence of 2π reset error of saw-tooth wave on system is analyzed. A phase bias around π/2 is obtained by use of a saw-tooth modulation signal with frequency at 94.05 kHz, and reset voltage of 10.84 V. Acoustic signal is gotten directly by A/D converter trigged by a pulse signal synchronized with saw-tooth modulation signal, and the influce of 2π reset error is depressed. The results show that when the system frequency is 10 kHz, the average amplitude of the signal is 0. 067 rad, with variance of 3.08× 10^-5 rad and ralative variational amplitude of only 0. 046 %. The phase bias of system is quite steady.