泵浦激光器驰豫振荡噪声对光纤激光水听器的影响

Influences of Relaxation Oscillation Noise of Pump Laseron Fiber Laser Hydrophones

对采用相位生成载波解调的光纤激光水听器系统中3kHz附近频域内固有噪声的产生机理进行了理论推导,并设计实验进行验证.首先测量得到泵浦激光器的驰豫振荡频率峰值,随后以400 Hz为间隔逐渐降低相位生成载波信号频率,观察固有噪声峰值的移动方向和大小.实验结果表明,随着载波信号频率的降低,固有噪声峰也向低频方向移动,移动间隔同样为400 Hz.可知相位生成载波解调算法中高频载波调制信号与泵浦激光器的驰豫振荡频率叠加是形成探测频谱固有噪声的主要原因.通过降低高频载波调制信号频率的方法对驰豫振荡噪声进行抑制,消除了探测频谱中的固有噪声峰,得到了较为平坦的本底噪声谱.

In phase generation carrier demodulation of fiber laser hydrophone, the physical mechanism of inherent noise near 3 kHz is analyzed theoretically and proved by an experiment. The relaxation oscillation peak of pump laser is measured firstly, and the carrier signal frequency is gradually reduced at an interval of 400 Hz to observe the movement direction and magnitude of the inherent noise peak. The experimental results show that with the decrease of the carrier signal, the inherent noise peak moves to the low frequency direction, and the movement interval is also 400 Hz. Therefore, it is considered that carrier signal superimposed with the relaxation oscillation noise of pump laser is the cause of the inherent noise. Finally, the inherent noise is suppressed and a relatively flat background noise spectrum is obtained through reducing the carrier signal freauencv of ohase ~eneration carrier demodulation algorithm.