Characteristics of few-mode fibre and its application in simultaneous strain and temperature measurement

摘要

This paper discusses a novel detection scheme to measure strain and temperature simultaneously using a section of specially designed few mode fibre (FMF). The work shows that the propagation constant difference between LPSUB01/SUB and LPSUB02/SUB modes, Δβ, has a maximum at the critical wavelength (CWL) in the transmission spectrum. Theoretical analysis and experimental verification indicate that the peaks located on each side of the CWL shift to opposite directions under strain and temperature variations. The two peaks located closest to the CWL from both sides, Left Peak 1 and Right Peak 1, shift linearly with indeed different and high strain and temperature sensitivities, when an appropriate length of FMF is chosen, allowing such a device to be used to simultaneously measure strain and temperature over a known range.