Investigation into Fiber Optic Seismic Sensor incorporating Fiber Bragg Grating Array

Abstract

This paper presents a theoretical study of various types of fiber optic sensing systems used for seismic monitoring integrating a series of fiber optic Bragg gratings (FBGs) into the sensor carrier. The interference network contains groups of interfering subnets, and each subnet contains multiple interference networks. Each interferometer in the subband is implemented with a specific pair of fiber Bragg gratings and the sensing length of the fiber is placed between each pair of fiber Bragg gratings. Each fiber Bragg grating pair has a similar characteristic wavelength modified from the characteristic wavelength of all other fiber Bragg grating pairs in the subband. The subarrays are interconnected to minimize crosstalk of common wavelengths between the sensors throughout the interferometer array. Our work is focused on investigating the selection of the best wavelength for use in the system. This study was performed using state-of-the-art simulation techniques for strain and temperature changes in FBG sensor arrays. The cumulative results obtained will help designers achieve optimized performance of similar fiber optic hydrophones in the future. The wavelength range of 1300 nm has been shown to provide the best performance for this type of fiber optic hydrophone system.