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提出了一种以基于3×3耦合器的非平衡光纤Mach-Zehnder干涉仪为核心元件解调DFB传感信号的技术方案。运用光波导和偏振光理论,推导出干涉仪输出光强表达式,分析了干涉仪输入光偏振态对可见度以及相位噪声的影响;利用三路输出信号之间互存120°相位差这一特点,提出了一种解调算法。分析发现,该方案在干涉仪可见度不为0的前提下,能够克服可见度变化对干涉仪输出的影响,获得传感信号的线性输出。
A scheme of demodulating DFB sensing signal with unbalanced fiber Mach-Zehnder interferometer based on 3 × 3 coupler is proposed. Using the optical waveguide and polarized light theory, the expression of the output light intensity of the interferometer is deduced. The influence of the polarization state of the input light of the interferometer on the visibility and the phase noise is analyzed. Using the characteristic of 120 ° phase difference between the three output signals , Proposed a demodulation algorithm. The analysis shows that under the premise that the visibility of the interferometer is not 0, the scheme can overcome the influence of the change of visibility on the output of the interferometer and obtain the linear output of the sensor signal.