不同相位调制波形对背向散射噪声的抑制

Backscattering Noise Suppressed by Different Phase Modulation Waveform

谐振式光纤陀螺系统中,背向散射噪声成为制约其系统精度的重要因素之一.对陀螺双路系统其中一路光波信号进行研究,利用相位调制频谱展开及光场叠加的方法,对光纤环形谐振腔输出光场进行理论分析.理论上载波分量的出现会在系统中引入背向散射噪声,因此仿真分析引入载波分量的幅度,得到采用三角波调制比正弦波更有利于抑制载波分量.以抑制载波分量为目标,搭建自外差载波抑制测试平台,对相位调制器施加三角波与正弦波两种波形调制,得到采用三角波调制时载波抑制比最高可达64.3dB,比正弦波调制时高出6dB,与理论分析相符;在陀螺系统应用中,采用三角波调制时陀螺输出信号载波抑制程度更大,波动更小,更加稳定.

Backscattering noise is an important factor to restrict the accuracy of resonator fiber optic gyroscope.The investigation on the lightwave signal in one loop of the gyro system was conducted.According to the expansion of phase modulation spectrum and optical field overlapping method,the transmission characteristics of fiber ring resonator were analyzed.The carrier component could introduce backscattering noise in the gyro system.The amplitudes of carrier component were simulated and analyzed,which showed that triangular wave modulation was superior to sinusoidal wave modulation.To suppress carrier component,the self-heterodyne carrier suppressed system was set up.The triangular wave and sinusoidal wave were applied to the phase modulator,respectively.The experiments show that carrier suppressed ratio of triangular wave modulation could reach 64.3dB,which is 6dB higher than sinusoidal wave modulation.The experimental results are consistent with the theory.Applied to the gyro system,carrier suppressed degree of the output signal is bigger,the fluctuation is smaller,and the gyro output is more stable using triangle wave modulation.