Study On The Theory And Experiment Of Fiber Cavity Ring-down Technology

Fiber cavity ring-down technology is a new type of sensing technology that appeared at the beginning of the 21 th century.It combines the traditional optical cavity ring-down technology with the optical fiber systems,which not only retains the advantages of the fiber cavity ring-down technology,such as high sensitivity,rapid response,and is not affected by the fluctuation of light intensity,and also avoids the need to maintain the optical path collimation in the traditional optical cavity ring-down system.Therefore,it is widely concerned by researchers.In this paper,it has carried out in-depth theoretical analysis and experimental research on fiber cavity ring-down technology.And the main research contents and results are as follows:(1)An in-depth analysis of the principle of fiber cavity ring-down technology is carried out,and the expression of fiber loop cavity ring-down system and fiber linear cavity ring-down system's ring-down time ? is derived.The influence factors of the ring-down time ? are discussed.On this basis,the mutual restriction and influence of the pulse width,repetition frequency,cavity length,the minimum detectable power of the detector,oscilloscope bandwidth,resolution and other device parameters in the fiber cavity ring-down system are analyzed,which provides theoretical support for the establishment of the subsequent fiber cavity ring-down experimental system.(2)A set of fiber cavity ring-down system was built and the experiment of solution refractive index sensing was successfully carried out.The sensing sensitivity of the system was 182.17?s/RIU.After that,several improvements were proposed based on the current deficiencies of this system.(3)The principle and preparation method of several other sensors are introduced.And in the meanwhile,two kinds of multichannel multiplexed fiber cavity ring-down systems for large range or multi-point measurement are designed and simulated.The advantages and disadvantages of the two systems are compared and analyzed according to their structures.