带加速度补偿平面型光纤光栅水听器探头技术的研究

针对平面型光纤Bragg光栅(Fiber Bragg Grating,缩写为FBG)水听器探头加速度响应明显,影响它对正常声压进行探测的需求,提出了采用加速度补偿措施进行加速度去敏这一有效方法。从理论和实验上分析研究了带加速度补偿平面型光纤FBG水听器探头的结构灵敏度、灵敏度频率响应特性和加速度响应特性。结果表明:采用加速度补偿措施后,单位加速度(1m·s^-2)响应输出的等效作用声压由2.52~3.26 Pa降为0.0758~0.217 Pa。同时,探头结构灵敏度由28 fm/Pa减小为20 fm/Pa,动态谐振频率由6.2 kHz增高为6.52 kHz。谐振频率的增加有助于提高水听器系统的动态响应特性,而结构灵敏度的降低,可以通过提高FBG动态波长解调仪的灵敏度来进行补偿。本来,光纤光栅或光纤光栅激光水听器系统可探测灵敏度主要由解调仪灵敏度决定,而不是由探头结构灵敏度决定。所以,该加速度补偿措施具有很大的实用性。

Research of the planar optical fiber bragg grating hydrophone probe with acceleration compensation methods

Aimed at that the probe acceleration response of planar FBG hydrophone is very obvious and has an adverse influence of the normal underwater acoustic pressure detection,An acceleration desensitization method using the acceleration compensation measure is put forwards in this paper.Research result shows that by this step,the equivalent pressure output applied by one unit acceleration(1 m·s-2) is reduced from 2.52~3.26 Pa to 0.0758~0.217 Pa. At the same time,the structure sensitivity is also decreased from 28 fm/Pa to 20 fm/Pa,however,the resonance frequency is increased from 6.2 kHz to 6.5 kHz.The increased resonance frequency help to improve itself dynamic frequency characteristic,however,the reduced structure sensitivity can be compensated by improving the FBG dynamic wavelength interrogation sensitivity.Originally,with regard to the FBG or FBG laser hydrophone,the system detectable sensitivity is mainly determined by its wavelength interrogation sensitivity,not the probe structure sensitivity.So this acceleration compensation method is of considerable utility.