Optical characterization of strain sensing cables for Brillouin optical time domain analysis

Abstract

Two innovative optical fiber cable layouts designed to improve strain measurement accuracy for Brillouin Optical Time Domain Analysis (BOTDA) sensors through improved strain transfer efficiency are presented and discussed. Swept Wavelength Interferometry (SWI) is used to experimentally evaluate their performance alongside analytical models and numerical simulation through Finite Element Method (FEM). The results show good agreement between the different methods and show that the second sensing cable design presents good features to minimize the mismatch between measured and actual strain. Finally, the strain response of both strain and temperature sensing cables of this design are evaluated, showing that their difference in response is reliable enough to allow temperature compensation.

Keywords

• brillouin scattering
• optical fiber sensors
• fiber ring lasers
• strain transfer
• structural health monitoring