全光纤多重回馈液体折射率测量

Measurement of all-fiber multi-feedback liquid refractive index

针对传统激光干涉折射率测量精度易受环境扰动,样品用量大等问题,本文提出一种全光纤多重回馈液体折射率测量系统。该系统以光纤光栅激光器作为内腔,以中空光纤作为外腔构成基于封闭式双重外腔激光回馈液体折射率测量系统,并对光纤结构的模式耦合效率、液体折射率测量精度进行了理论分析与计算。实验结果表明,该系统的理论测量精度可达到3.44×10^(-5),由于采用了闭合光纤元件一体熔接,因此对热抖动和机械振动表现得更稳定,待测样品不需要匹配,也没有被污染的危险。该系统将微纳器件和流体力学相结合,可构造出物理、化学、生物等科研所需的特殊研究环境,具有快速、高效,样品取样少等优点。

As one of the most important optical parameters of a liquid,the refractive index has significant applications in many fields.The conventional laser interference method for measuring refractive index is highly susceptible to disturbances in the environment,and it also requires a large number of samples.To address these issues,in this study,a fiber grating laser is used as the inner cavity and a hollow fiber is used as the external cavity to form a closed,dual-external-cavity laser feedback system for measuring the refractive index of a liquid.The mode coupling efficiency of the fiber structure and the accuracy of the measured refractive index of the liquid are theoretically analyzed and calculated.The results indicate that the theoretical measurement accuracy of the system can reach 3.44×10^(-5).As the design adopts the integrated fusion splicing of closed optical fiber components,the system is more robust against thermal jitters and mechanical vibrations.Moreover,the samples to be tested need not match,and there is no risk of contamination.The proposed system combines micro-nano devices and fluid mechanics,and it can construct a special research environment required for scientific research in fields such as physics,chemistry,and biology.