一种具有声低通滤波特性的无源零差光纤水听器

A Novel Passive Homodyne Fiber-Optic Hydrophone of Acoustic Low-Pass Filtering

报道了一种新颖的具有抗混叠功能的无源零差迈克耳孙型光纤水听器。它由一个普通的芯轴型光纤水听器和一个圆柱型亥姆霍兹共振器构成。在驻波罐中对其声压相位灵敏度频响进行了测量，结果表明该光纤水听器具有较好的声低通滤波特性，能有效地抑制声信号中的高频成分，从而实现抗混叠滤波。该光纤水听器的低频声压相位灵敏度主要由传感光纤长度和弹性增敏层的物理特性决定，约为-159 dB（0 dB=1rad／μPa）。在1150Hz附近出现了一个共振峰，这主要由圆柱型亥姆霍兹共振器的声学特性决定。1150～2280Hz频段内的灵敏度衰减率约为50dB／倍频程，1500Hz以后的灵敏度衰减量大于10dB。这对于提高我国未来声纳系统的抗干扰能力具有十分重要的意义。

A novel passive homodyne Michelson interferometric fiber-optic hydrophone of anti-aliasing has been manufactured and demonstrated. This new fiber-optic hydrophone consists of a conventional mandrel fiber-optic hydrophone and a metal cylindrical Helmholtz resonator. The acoustic pressure phase sensitivity response has been measured in a standing-wave tube filled with water. Experimental results show that this new fiber-optic hydrophone is of acoustic low-pass filtering, which makes it available for suppressing high-frequency components in acoustic signal and eliminating aliasing in the future sonar system. The low frequency sensitivity of this fiber-optic hydropbone, as determined by the length of the sensing fiber and the performance of the elastic layer, is - 159 dB （0 dB = 1 rad/μPa）. The frequency response has a resonance peak near 1150 Hz, which is determined by the cylindrical Helmholtz resonator. There is a measured roll-off of 50 dB/octave over the range of 1150- 2280 Hz. The acoustic sensitivity attenuation beyond 1500 Hz is bigger than 10 dB. This new fiber-optic hydrophone is very important for enhancing the operation performance of the future sonar system.