分析了一种有源型光纤水听器的水声传感原理, 在一段掺铒光纤中写入具有π相移的光纤光栅构成光纤激光器, 水声压力作用在激光器上引起激光波长的移位, 采用干涉法检测出波长移位引起的相位变化即得到声压的信息。水声探测实验表明, 有源型光纤水听器的声压灵敏度为-166.5 dB(参考值1 rad/μPa)。将不同工作波长的四元光纤水听器串接于一根光纤内组成水听器阵列, 使用带通波分复用器将阵列发出的激光分离至各独立通道后检测出相应的声压信号, 测得水听器之间的级串扰小于-60 dB, 且单元水听器水声响应的动态范围不受影响。

The acoustic sensing characteristics of an active optic fiber hydrophone was analyzed. The fiber laser sensor is made by writing Bragg grating with πphase-shift into a section of Er-doped fiber. Acoustic pressure applied to the fiber laser induces laser wavelength shift. The wavelength shift is demodulated through interferometric interrogation scheme, and the acoustic pressure information is obtained. The sensitivity experiment shows that the sensitivity is -1665 dB(reference value, 1 rad/μPa). Four optic fiber hydrophones were spliced along a single fiber to form an array. A band-pass wavelength division multiplexer was used to separate the composite interferometer signal into discrete channels and demodulate the acoustic pressure information. The experiment shows that the crosstalk of the array is less than -60 dB, and it will not affectthe dynamic response range of a single hydrophone.