Analysis Of The Influence Of Output Signal Intensity On Cavity Ring-down Measurement Accuracy

Based on the obvious advantages of optical feedback cavity ring down method in the measurement of optical elements,an optical cavity ring down experimental device which can measure high reflectivity is built by using the self mixing characteristics of semiconductor laser.The influence factors of the accuracy of the measurement results and the influence of the output signal strength of the resonator on the accuracy of the measurement results are analyzed In the process of supersaturation,the ring down time,signal amplitude and the change trend of DC signal of the optical system are analyzed.According to the different segments of the output signal,the fluctuation range of optical parameters under different signal intensities is calculated.The main work of this paper is as follows:(1)The application background and research status of cavity ring-down technology are systematically investigated,and the principle and system structure of the initial cavity ring-down measurement of reflectivity,the insertion of high reflective optical elements and the insertion of high transmittance optical elements are deeply studied,which provides theoretical guidance for the final determination of the test scheme.(2)The optical cavity ring down system based on optical feedback is built,algorithm implementation and hardware selection are completed.The system can measure high reflectivity or high transmittance optical elements in a ring down system within 2m,and the measurement accuracy is within 99.9%.(3)The data fitting algorithm based on nonlinear least square method is realized.The L-M algorithm of origin and the function fitting methods of lsqcurvefit()and fittype of MATLAB are compared.When the measurement accuracy and measurement range are guaranteed,the measurement accuracy under different signal strength is analyzed.(4)Has carried out a large number of tests and analysis of the system,including:(a)the initial cavity signals,high inverse element,and the detection of the output signal of high transparent component,under the condition of considering the response time of system,using different fitting formula,analyzed the influence of the output signal intensity on the measurement accuracy(b)considering the effects of system noise,the output signal data capture different ring-down segment analysis(c)to get a better look ring-down signal and the relationship between cross section,choose to measured data log analysis.Through the work in this paper,the cavity ring-down signal data analysis based on the nonlinear least square method is analyzed,which provides a certain reference for improving the measurement accuracy of optical components,and has a certain significance.