Design And Research Of All-Fiber Double-Parameter Measurement Sensor

Fiber optic sensors have the advantages of strong corrosion resistance,electromagnetic interference resistance,high sensitivity,and integration.They are widely used in various fields to measure various physical parameters such as temperature,refractive index,curvature,and strain.In recent years,fiber optic interferometric sensors,which develop rapidly,has become a research hotspot of fiber optic sensors due to its low cost,easy operation and higher sensitivity.This paper studies two types of fiber sensors,one is a Long Period Fiber Grating(LPFG)based on the coupled mode theory,and the other is an interferometric sensor based on the intermode interference theory.Experimentally research on these sensors by analyzing the temperature characteristics and refractive index characteristics.The main research contents of this paper are as follows:A kind of long-period Fiber grating is designed based on the coupled mode theory.SMF,TCF and No Core Fiber(NCF)are interlinked and TCF is interspersed with NCF.Since the refractive index of NCF is different from TCF,it will perturb the refractive index of TCF and form a resonance peak.The resonance peak is simulated by RSOFT software,and the high-order mode in TCF cladding is stimulated by NCF.The sensor is verified to have the advantages of dual-parameter measurement of temperature and refractive index and had high sensitivity through the sensing experiment.The temperature sensitivity is 66pm/?,and the refractive index sensitivity reach780nm/RIUA kind of Mach-Zehnder fiber optic sensor based on peanut structure is designed,which is formed by connecting a piece of Tine Core Fiber(TCF)between two peanut structures which are spliced by Single Mode Fiber(SMF)and Few Mode Fiber(FMF).The performance of the sensor is simulated by RSOFT software,and the experiment verifies that the peanut structure can stimulate higher-order modes in TCF.The interference between modes produces interference spectrum.Since the selected two interference peaks have different wavelength shifts for temperature and refractive index,temperature and refractive index sensing can be carried out.Through the sensing experiment,it is verified that the sensor has the characteristics of twoparameter measurement of temperature and refractive index,and the maximum temperature sensitivity of the sensor is 310 pm/?,and the maximum refractive index sensitivity is 210nm/RIU.