Research On The Performance Of Semiconductor Sensitive Material Long-period Fiber Grating Sensor And Double-parameter Sensing

Optical fiber sensing technology takes light wave as carrier and optical fiber as medium.A new sensing technology senses and transmits the measured signal from outside.Due to the characteristics of optical fiber sensors that integrate information sensing and transmission,and the optical fiber sensors have incomparable advantages over traditional sensors due to their light weight,small size,anti-electromagnetic interference,corrosion resistance,high temperature resistance,low power consumption,and long-distance real-time monitoring,which solves many measurement problems that are difficult for conventional detection.The long-period fiber grating(LPFG)invented in the 1990s is a passive optical fiber device with periodic refractive index modulation,its super-large period determines that it has a completely different coupling mechanism compared with the traditional fiber Bragg grating(FBG)has a completely different coupling mechanism.LPFG usually has the period of tens to hundreds of micrometers.The LPFG couples light from the fundamental mode to the high-order and forward-propagating cladding modes the central wavelength and coupling strength are closely related to the changes of the external environment.In addition to the advantages of low cost,simple fabrication and easy integration,it also has the advantages of low insertion loss,sensitivity to multiple external parameters and no backward reflection,so it has a very broad development prospects in the communication,sensing and other fields.In the preparation of the fiber grating material of the optical fiber sensors,the sensitive material of the coating layer of the optical fiber grating sensor plays a decisive role in the sensitization characteristics of the optical grating sensor device during the preparation process.In this paper,the combination of semiconductor sensitive materials and fiber grating sensor components is used to improve the sensitivity of the sensitization characteristics of fiber grating sensors,thereby realizing high-sensitivity sensing tests.In this thesis,a new type of optical fiber sensor prepared by pulsed laser deposition(PLD)is studied theoretically.The influence of the thickness of the nano-sensitive film,the doping ratio of sensitive materials,the environmental temperature and pressure and other parameters on the sensing performance of the fiber grating were studied.In the experiment,the ceramic targets of semiconductor materials In₂O₃:Sn O₂(ITO),In₂O₃:Ga₂O₃:Zn O(InGaZnO)were prepared by solid-phase sintering method.The nano films of ITO and InGaZnO were coated on the sensitive optical fiber components,and the sensing properties were studied,and the best parameters of the sensitive film were obtained.In order to realize the multi-parameter cross-sensitivity in the multi-parameter sensing process,we designed and built a multi-parameter sensing system to realize the research of dual-parameter or multi-parameter sensing characteristics.The specific content is as follows:1.In theory,a four-layer mode of core-cladding-sensitive film-environment is constructed by combining the theory of coupled modes.The relationship between the effective refractive index of different modes with the environmental wavelength and environmental refractive index,the relationship between the coupling coefficient with the film thickness and the environmental refractive index,the relationship between the effective refractive index of the cladding mode with the film thickness and the film refractive index are simulated by software.Then the theoretical analysis is carried out.Find out the best sensitive film parameters of different materials(ITO,InGaZnO)to provide theoretical guidance for the preparation of the optical fiber grating sensors with sensitive film.2.The ceramic targets of doped material ITO and multi doped material InGaZnO were prepared by solid-state sintering.The ITO and InGaZnO-LPFG coatings were prepared,and the preparation of a new type of sensitized fiber grating sensor with high sensitivity and high stability was completed by PLD technology,and the physical and optical properties of the films prepared under different parameters were analyzed.The best preparation conditions of the films were obtained.The new sensitive film sensor with high sensitivity and high stability was prepared.The refractive index sensitivity of LPFG is up to 295 nm/RIU after doping semiconductor materials of ITO coating.After coating InGaZnO,the refractive index sensitivity reaches 338 nm/RIU,which is nearly 8 times higher than that before coating.3.It is proposed to use different sensitive optical fibers:FBG,PCF,TFBG,LPFG or sensitive films ITO,InGaZnO,combined with WDM technology to construct the dual-parameter fiber optic sensing or multi-parameter sensing system,which solves the problem of cross sensitivity in the process of optical sensing and realizes stability sensing of two or more parameters with high sensitizing sensitivity.