The High-temperature Sensing Characteristics Of Fiber Michelson Interferometer And Fiber Cantilever Beam

Since the 1960 s, fiber waveguide as the light transmission medium has been proposed by C. K. Kao; Since the first low-loss single mode fiber was fabricated by American Corning Corporation on 1970 s, optical communication technology has been developed rapidly and become one of pillar industries in today's information age. The optical fiber sensing technology as a branch of optical communication technology has been drawn more and more attention as well. In this paper, the optical fiber Michelson interferometric sensor has been mainly studied, and the fiber cantilever sensors based on the superposition of two sets of optical interference have been put forward on the basis of further optimization and verified. The sensing property in high temperature has been studied by experiments. The main contents are arranged as follows:1. Introduce the classification of optical fiber sensor and the research status of optical fiber Michelson interferometric sensor in workmanship. 2. A fiber Michelson interferometric sensor based on 45° tilted fiber end in single mode fiber for high temperature measurement has been fabricated by femtosecond laser. The light is mainly split into two beams at the 45° tilted fiber end which forms a Michelson interference. The temperature repetitive experiments demonstrate good repeatability and stability of the sensor. The temperature response curve shows a little nonlinear nature in the range from room temperature to 800 °C. The temperature sensitivity is obtained to be about 19.7 pm/°C at 1605 nm and 600 °C. It is equivalent to the accuracy of temperature measurement of 4.1°C. 3. A fiber Michelson interferometric sensor based on 45° tilted fiber end in thin core fiber for high temperature measurement has been fabricated by femtosecond laser. The temperature rises from 100 °C to 900 °C with a step of 100 °C. The wavelength of the reflection spectra move to the long wavelength and a red shift can be clearly observed. The temperature sensitivities are about 9.2 pm/°C and 47.5 pm/°C at 200°C and 600°C, respectively. 4. A 45° fiber cantilever beam for high temperature measurement has been fabricated by femtosecond laser in single mode fiber. The reflection spectra are composed of the superposition of two sets of optical interference. The main interference mechanism is based on 45° tilted fiber end Michelson interference while the air cavity mainly works on the big interference spectral envelope. The temperature sensitivity is obtained to be about 17 pm/°C in the range from room temperature to 1000 °C. The three temperature cycle experiments demonstrate the 45° fiber cantilever beam possesses good repeatability and stability in high temperature and wavelength. The experiment results show that the 45° fiber cantilever beam can withstand higher temperature since the effective sensing end has been protected well. 5. A 90° fiber cantilever beam for high temperature measurement has been fabricated by femtosecond laser in single mode fiber. The reflection spectra are composed of double Fabry-Perot interference in superposition. The temperature sensitivities are about 10 pm/°C and 17 pm/°C at 200°C and 600°C, respectively.