动态扰模抑制多模光纤散斑的理论及实验研究

Theoretical and Experimental Study on Suppression of Speckle from a Multimode Optical Fiber by Dynamic Scrambling

多模光纤传输相干光时,光纤出射光场将形成散斑现象。振动光纤能够很好地抑制这种散斑效应。为了研究施加在多模光纤上机械振动和散斑抑制之间的相互作用,从模式耦合速率出发,分别建立振动幅度、频率、作用长度和抑制效果之间的关系,并通过实验对理论结果进行验证。结果表明:动态扰模下散斑抑制效果随振动幅度增加而改善,且与频率、作用长度呈现非线性关系,同时提出并使用模式耦合速率对散斑抑制进行定性评价,为研究人员利用动态扰模抑制多模光纤散斑提供理论依据和实验参考。

When a coherent beam transmits by a multimode fiber, speckles will appear in the output field. Vibrating the fiber is approved to be an effective way to suppress the speckles. To reveal the relationship between the vibration parameters and the suppression effect, we establish the formula connecting the amplitude, frequency, acting length to the speckle improvement based on the rate of mode coupling. The experiment results confirm the trend： the suppression effect improving with vibration amplitude, and changing nonlinearly with the frequency ,acting length. Therefore the rate of the mode coupling can evaluate the suppression effect qualitatively. The results provide theoretical proof and experimental reference.