| In recent years,optical fiber sensor has attracted the attention of scholars at home and abroad because of its compact structure,high sensitivity and strong anti-interference ability.It has become a research hotspot for domestic and foreign scholars because of the high sensitivity detection by preparing optical fiber,changing the structure of sensor or designing improved experiment system.The transmission mode of grapefruit microstructured fiber is abundant,and the cascade structure with single mode fiber is simple,So the combination of the two has important research significance.This paper summarizes and analyzes the research status of different types of optical fiber torsion sensors at home and abroad.A new optical fiber torsion sensor is proposed.It is using grapefruit microstructural fiber as the sensing unit,and the cascade structure is both sides of the grapefruit microstructured fiber are single mode fibers.Its torsion sensing characteristics under two different torsion experimental systems are deeply studied.The main contents are included as follows.Firstly,the transmission mode and inter-mode interference principle of grapefruit microstructured fiber are studied,and the multi-layer optical waveguide structure,the formation of interference lines and the spectral simulation are analyzed in detail.Secondly,a new optical fiber sensors are designed and fabricated for the cascade structure of grapefruit microstructured fiber and single mode fiber.The preparation process of sensor is studied and the influence of different fiber length and discharge intensity on transmission mode and spectrum is analyzed.Thirdly,a coaxial torsion experiment system is designed and built.The effects of two torsion directions clockwise and counterclockwise on different lengths of grapefruit microstructured fiber are analyzed.The torsion characteristics of the prepared sensor with different lengths are measured.The torsion sensitivity are obtained and analyzed.Finally,a non-coaxial torsion test system are designed and built.The effects of clockwise and counterclockwise torsion directions on different lengths of grapefruit microstructured fiber are analyzed.The torsion characteristics of the prepared sensor with different lengths are measured.The torsion sensitivity are obtained and analyzed. |
