光纤干涉系统光学湍流测量原理及其偏振噪声问题的分析

光纤干涉仪具有测量精度高、探测灵敏度大等优点,可用于直接测量大气湍流折射率起伏.首先简要介绍了光纤Mach-Zehnder干涉仪的光学湍流测量原理,描述了低双折射单模光纤中光束偏振态变化诱导的偏振信号衰落现象,并通过偏振态的邦加球分析和详细的公式推导,得出了干涉仪可见度和相移噪声的关系式.结果表明:控制输入光偏振态与干涉仪本征向量之间的夹角在零度左右,可有效地抑制偏振噪声,最后给出了偏振控制器实现偏振控制的原理,为构建稳定的光学湍流测量光纤干涉系统提供了科学依据.

Principle of fiber interferometer measuring optical turbulence and analysis of polarization noise

The high precision fiber optical Mach-Zehnder interferometer is suitable for the measurement of refractive index fluctuations in turbulent atmosphere.However,the variation of polarization state,called polarization noise,in low birefringence single mode optical fiber causes the phenomenon of signal fading.The expressions of interferometer's output power, fringe visibility and phase noise are obtained through the method of Poincare sphere analysis. Angle of polarization between input light and optical fiber interferometer must be controlled at about zero by adding mechanical polarization controller.So polarization fading and phase noise can be restrained.Furthermore,manipulative principle of polarization controller is showed.It is an indispensable method to construct optical fiber interferometer of stabilization for optical turbulence.