三波长数字相位解调法解调误差及影响因素

Demodulation error and influencing factor of three-wavelength digital phase demodulation method

介绍了光纤法布里-珀罗(F-P)传感器的传统解调方法,系统地推导了针对非本征法布里-珀罗干涉型(EFPI)传感器解调的三波长数字相位解调法的解调原理,仿真和实验分析了三波长数字相位解调法的解调误差。仿真分析结果表明,相位偏离正交关系是限制解调的最主要因素,要保证解调误差在15 nm以内,腔长变化应小于在正交腔长处2μm的范围。采用3个独立的激光光源进行实验,实验结果表明,在正交腔长附近1μm范围内变化,解调腔长误差小于12 nm,重复性误差小于10 nm,解调具有良好的稳定性。

This paper introduces the traditional demodulation method of Fabry-Perot（ F-P） sensors,and systematically derives the demodulation principle of three-wavelength digital phase demodulation method using extrinsic Fabry-Perot interferometer（ EFPI） sensors. Meanwhile,simulation method has been used to analyze the demodulation error of three-wavelength phase demodulation method. The results indicate that the phase deviation from an orthogonal relationship is the most important influencing factor limiting the demodulation. In order to ensure that demodulation error is less than 15 nm,the cavity length change should be within the range of 2 μm at the orthogonal cavity length. Three independent laser light sources have been used to do the experiment. The results show that when the cavity length changes within 1 μm from orthogonal cavity length,the error of the demodulation cavity length is less than 12 nm,and at the same time the repeatability error of the demodulation is less than 10 nm,which means that demodulation has good stability.