Distributed Fiber Optic Interferometric Geophone System Based on Draw Tower Gratings

摘要

A distributed fiber optic interferometric geophone array based on draw tower grating (DTG) array is proposed.The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a phase mask during the fiber drawing process.A distributed sensing system with 96 identical DTGs in an equal separation of 20 m and an unbalanced Michelson interferometer for vibration measurement has been experimentally validated compared with a moving-coil geophone.The experimental results indicate that the sensing system can linearly demodulate the phase shift.Compared with the moving coil geophone,the fiber optic sensing system based on DTG has higher signal-to-noise ratio at low frequency.