Optomechanical Behaviour of Coated FBG Sensor with Side Hole Package Technology for Underwater Acoustic Applications

Abstract

Ocean is receiving global attention for research in underwater communication. Acoustic wave is the main carrier of information in underwater sensing technology. In the proposed work we developed cylindrical and side hole package fibre optic based acoustic pressure sensor. Sensitivity of both the package and bragg wavelength for each change is strain is investigated. Both cylindrical and side hole package is optimized for two different types of coating material. i.e. Silicon rubber and poly methyl methacrylate (PMMA). Both the package is designed in Ansys tool. Strain generated at the core part of package due to applied pressure, effective refractive index change and Bragg wavelength shift is explored. Larger strain variation and with step size of 0.01 for side hole package with PMMA material. Maximum sensitivity of 851nm/RIU is obtained for PMMA with side hole package enhanced pressure sensitivity of proposed design opens the more possibilities for different applications of underwater acoustic and feasibility for fabrication. Remarkable sensitivity of 162nm/RIU is for cylindrical package with silicon rubber and 158nm/RIU for silicon rubber with side hole package and 161nm/RIU for PMMA with cylindrical package is obtained. Designed side hole package with PMMA coating shows more feasibility for fabrication for underwater application in future.