Study On Multi-parameter Measurement Fiber-optic Srnsor Based On Fabry-Perot And Antiresonant Mechanisms

Fiber-optic Fabry-Perot(FP)interference sensors have the advantages of high detection accuracy,high sensitivity,small size,light weight,immunity to electromagnetic interference,corrosion resistance,and resistant to environmental disturbances compared with traditional mechanical and electronic sensors.It has been widely used in structural health testing,aerospace,biomedical,marine detection and other fields.Antiresonant(AR)waveguide fiber is a low-refractive index-core photonic crystal bandgap optical waveguide,which can be used for measurement of physical quantities such as air pressure and temperature by using the characteristic peak of its spectrum to drift with the change of core or cladding refractive index of the fiber.In this paper,the principle of FP type and AR type fiber-optic sensors and multi-parameter sensors are studied in the existing optical fiber sensing technology methods in recent years.The two mechanisms of FP and AR are combined in the same structure.Several new multi-parameter sensor schemes were carried out,and theoretical studies,sensor preparation,experimental tests and analysis of experimental results were carried out.The experimental results show that the sensor can measure temperature and other physical quantities at the same time,effectively solving the cross-crosstalk of temperature during sensor measurement,which is of great significance for the development of optical multi-parameter sensing technology in the future.Aiming at solving the problem that the fiber-optic strain sensor is susceptible to external temperature,this paper proposes a fiber-optic sensor based on FP interference and AR mechanism for simultaneous strain and temperature measurement.The sensor has a simple structure,and only uses a SMF(Single-mode Fiber)-HCF(Hollow-core Fiber)-SMF structure in which a HCF is fused between two SMF.The FP interference and AR mechanisms are combined in the hollow fiber.Since the FP interference spectrum only responds to strain,and the AR mechanism spectrum only responds to temperature,the two spectra can measure strain and temperature changes separately,and simultaneously measure strain and temperature.In addition,the preparation process of the sensor is very simple.The fiber used is common,so the cost is low.The structure of the sensor is compact and the size is small,which is beneficial to the application of the sensor.Aiming at solving the problem that the fiber-optic pressure sensor is susceptible to ambient temperature,this paper proposes a fiber optic sensor based on FP interference and AR mechanism for simultaneous strain and temperature measurement.The sensor uses HCF as the sensing unit.On the basis of the SMF-HCF-SMF structure,the HCF core is connected to the external environment by means of misalignment welding or welding a thin-core hollow core fiber(TCHCF)after the HCF.The sensor also combines the FP interference and AR mechanisms in the hollow fiber.The spectra of the two mechanisms have different responses to air pressure and temperature.The spectra of the two mechanisms are separated and tested for different sensitivity to air pressure and temperature.The sensitivity coefficient matrix equation is established,and the different sensitivity of the two mechanisms to the pressure and temperature can compensate for the pressure-temperature cross-sensing problem of the sensor.