Due to their unique advantages, including light weight, low-cost, immunity to electro-magnetic interference, et al, optical fiber sensors (OFS) have found wide applications in many fields. Nowadays a large number of OFS have been developed, including temperature, stress/strain, vibration, acoustic wave and gas sensors, et al. However, there still exist gaps to meet end-user’s demands, such as problems of resisting in harsh environments, lack of FBG multiplexing networks with large capacity, low-cost demodulation devices and OFS systems. Therefore, application-orientated developments are essential to solve the problem between research investigation and industrial applications.
The National Engineering Laboratory for Optic Fibre Sensing Technologies at Wuhan University of Technology has conducted R&D activities on OFS for >30 years, and this presentation will overview on main technical achievements, including demodulation technology of FBG in harsh environments such as high temperature, large strain etc, multi-point monitoring with large capacity FBG networks, various forms of demodulators, and complete technology and system development. Also, a number of industrial applications to civil engineering will be presented, including: (1) long-term safety monitoring of the highway railway cable-stayed bridge with the largest span and load in the world; (2) fire safety monitoring of the world's longest road tunnel; (3) long-term leakage and structure safety monitoring of the world's highest concrete face dam; (4) fire alarm systems in four national strategic oil storages and 90% of large oil tanks in China Petrochemical Company, et al.As for fundamental research, the combination of fibre optics with nano-structure technologies and sensitive thin films offers great potential for the realization of novel OFS concepts. Miniature OFS with thin films as sensitive elements could open new space for OFS applications. Thin films work as sensitive elements and transducer to obtain response and feedback from environments, optical fiber here are employed as the signal carrier. This paper will present some fundamental research work conducted in recent years, including: (1) Pd/WO3 co-sputtered coating as sensing material for optical hydrogen sensing shows robust mechanical stability and meanwhile good sensing performance; (2) TbDyFe magnetostrictive coating directly deposited on FBG demonstrates the possibility as miniature optical magnetic field/current sensors; (3) Miniature OFS based on the Fabry-Perot thin film structure are also proposed, and the transducer deposited on fibre end-face is multilayer coating consisting of a stack of nano-porous silicon film sandwiched with two silver coatings as mirror layers. The reversible adsorption and desorption of water molecules in the porous films in dependence on water vapor causes the shift of the reflected interference spectrum fringe, therefore humidity sensing is correlated with such a shift; (4) Finally, micro-structured Farby-Perot sensors on single mode fibre and photonic crystal fibre are realized with the 157nm excimer laser
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