A Research On The Demodulation System Of Fiber Bragg Gratings With The Same Wavelength

In recent years, Fiber Bragg Gratings are being used in national defense construction,industrial and agricultural production, quality inspection and other fields as it hasadvantages such as strong anti-jamming capability, small size, and easy to form a network.Along with the continues development of FBG-related technologies, the scope of FBGapplications is expanding step by step, thus experts and scholars lay more emphasis on thefiber grating sensing technology. FBG has become the optical devices with developmentpotential and application prospect within optical fiber passive components, providing newcomponents to optical fiber communication and sensing areas. This paper mainly focus onthe exploration of new fiber grating sensing technology that can reduce costs andaccelerate the study of the application of fiber grating sensing technology. This thesisincludes;In order to clearly understand the contents and significance of this study, a comprehensivesummary of the status quo of the domestic and international fiber optic sensing technology has beenmade.Starting from the sensing principle of the fiber grating and using the coupled mode theory, therequirements that need to be met when fiber Bragg grating transmits can be found. Based on theserequirements, a further analysis of the sensing properties of the fiber Bragg grating about temperatureand pressure has been made, after which the Bragg temperature and pressure cross sensitive issue hasbeen deeply discussed. This paper focuses on the theoretical analysis of the multiplexing capability ofweak anti-fiber Bragg grating, verifying the possibility of multiplexing gratings with the same centerwavelength in an optical fiber in a theoretic way.By comparing with the traditional demodulation scheme, a low-cost, high-precision,easy-multiplexing Bragg sensing system that can simultaneously demodulate multiple gratings with thesame center wavelength was designed. This paper focuses on its system demodulation method.Finally, three fiber-grating sensors with the same wavelength were experimented on demodulation,proving the possibility of time-domain demodulation via an experimental way.In this paper, time domain demodulation system was proposed, and the experiments of temperature features of three gratings on the same wavelength grating in the condition of 20 ~ 60℃have been done. In future research, the improvements could be carried on multiplexing numbers,experimental environment, and demodulation precision to meet the requirements in actual projects.