Research On Cascaded Double Loop Sensor Based On Transmission Spectrum Envelope Fitting Method

For nearly forty years,China has always adhered to the road of deepening reform and opening up,so it has been at the forefront of the world in economics,industry,science and technology.However,with the rapid development of society,it has also brought many problems,such as environmental pollution,food safety and water quality and health.In order to improve people's quality of life and guarantee the fruits of reform and opening up,it is urgent to solve these problems.Due to the advantages of high sensitivity,anti-electromagnetic interference,and small device size,SOI-based optical waveguide sensors have great potential in the application market to solve the above problems.This paper mainly studies sensors based on cascaded dual-ring resonators,uses the envelope fitting method to improve the detection limit and detection accuracy,and explores a new detection method combined with thermal tuning.In this paper,the transmission spectrum transfer function,sensing principle and performance parameters of the micro-ring resonator sensor are first theoretically explained.Then,the manufacturing process of the sensor chip is introduced,the microfluidic channel with better sealing is designed,the package of the chip and the fiber array is completed,and the wavelength test system is set up.Next,the temperature characteristics of the sensor were studied,and the volumetric refractive index sensing performance of the sensor was tested using a gradient concentration NaCl solution.Finally,the reasons for the reduction of sensor detection limit and detection accuracy caused by the vernier effect are analyzed,and an error evaluation method is introduced.It is demonstrated from simulation and experiment that by fitting the transmission spectrum envelope,the detection limit can be increased by 7 times,and the sensitivity measurement error is reduced from 40.12%when not fitted to 0.53%after fitting using the gauss3 function model.Combining the envelope fitting method with thermal tuning,the sensitivity of the sensor under thermally tuned wavelength detection is 34413.49mw/RIU.