Research On Temperature Sensor Base On All-fibre Mach-Zehnder Interferometer

Fiber Optic Sensor is a high-tech discipline which melts fiber optics, micro-electronics, precision machinery, computers technologies and so on. So it can be called a difficult technological industry with extensive cooperation of multi-subject. It has become the urgent affairs that the corresponding theory should be deeply studied and the novel fiber optic sensors be developed .Fiber optic sensor can be categorized by the principle of fibre optic sensor,the object measured, and signal modulation method and so on. According to the light wave parameters which is modulated , Fiber optic sensor is classified into five kinds of optical-fiber sensor, namely, intensity modulation fiber-optic sensor, phase modulation fiber-optic sensor, frequency modulation fiber-optic sensor, polarization modulation fiber-optic sensor, wavelength modulation fiber-optic sensor. The current research status of domestic and overseas fiber optic sensors are summarized in this paper. And then a kind of phase modulation fiber-optic sensor based on Mach-Zehnder interferometer structure is designed and studied.The all-fiber Mach-Zehnder interferometer is an important interference devices with the virtues of small size, light weight, compact structure and high sensitivity. Therefore, many important applications of it has been found and will be developed during the fiber-optic communications and optical sensing regions.Firstly, the basic principle of phase modulation type optical fiber sensor and demodulation technology are reviewed in this paper. Secondly, the basic principles, the research status and the applications of Mach-Zehnder interferometer are depicted. Then the all-fiber Mach-Zehnder interferometer is studied theoretically and numerically simulated with scattering matrix method and interference analysis method, respectively. The influence of the circumstance on the interference effect of the Mach-Zehnder interferometer is analyzed. On this basis, A kind of temperature sensor device based on all-fibre Mach-Zehnder interferometer is designed through phase modulation method. The Mach-Zehnder interferometer has been studied experimently. During experiment, through changing the path difference of the two arms of the Mach-Zehnder interferometer by changing the temperature, we study the relationship between the output spectrum of the Mach-Zehnder interferometer and external temperature. Adopting the wavelength scale method ,we get the relationship between the shifting wavelength and external temperature While temperature is from 26℃—80℃. The tuning range is 0. 957 nm .The phase range is about Aπ. The fitting linearity is up to 0.972. The experimental results show good consistency with the theoretical ones.Experimental results show that the design of the sensor has the advantages of simple-structure, higher-sensitivity, low-price, easy to apply in practice. So it has extensive application value in the sensing regions.