DFB光纤激光器声致弯曲振动研究

A study of acoustically induced bending vibration of DFB fiber laser

对利用DFB(分布反馈式)光纤激光器进行水声探测时的弯曲振动问题进行了分析与实验研究。总结了采用非平衡干涉仪解调系统解调的DFB光纤激光水听器的声压灵敏度计算公式;基于梁的弯曲理论,通过数值方法计算了两端固定的DFB光纤激光器在50Hz^2000Hz频率范围内的声压灵敏度,绘制了该频率范围内的频响曲线;采用振动液柱法对一支DFB光纤激光器在该频率范围内进行了实验研究,实验数据具有良好的可重复性,实验结果与理论分析吻合。表明了细长型结构的DFB光纤激光器在水声场中很容易由于弯曲振动而引入较大的非声压振动的干扰信号,影响其水声探测性能,有必要在DFB光纤激光水听器探头的设计中考虑这一因素。

Theoretical analysis and experimental study of the bending vibration of DFB （Distributed Feedback） fiber laser in the underwater sound field are carried out. The calculating expression of the acoustic pressure sensitivity of the DFB fiber laser hydrophone, whose signal is demodulated by an unbalanced interferometer system, is concluded. And based on the theory of beam, the sensitivity in the frequency range of 50 to 2000 Hz of the DFB fiber laser, both ends of which are fixed, is calculated out by numerical method. And accordingly, the frequency-response curve is figured out. A DFB fiber laser hydrophone is experimentally studied in the frequency range, the experimental data is repeatable and in good agreement with the theoretical results. It is indicated that the DFB fiber laser is ready to be induced with bending vibration by ambient disturbance in underwater sound field, due to its thin and lengthy configuration. And along with that, vibration noise will be led into the signal output of acoustic pressure, and as a result, the acoustic characteristics of the DFB fiber laser will be influenced, and in the design of DFB fiber laser hydrophone unit, the influence should be taken into account.