In-fibre temperature sensor based on Mach-Zehnder interferometer via dual-mode concentric multilayer-core fibre

An in-fibre temperature sensor based on a novel dual-mode fibre is proposed and experimentally characterized. The sensor head uses an in-fibre Mach-Zehnder(MZ) structure to sense the surrounding temperature, which depends on the interference spectrums. The concentric multilayer-core fibre (CMCF), in which only two modes could be propagated, would be easier to fabricate an in-fibre MZI with clean spectrum than many fibres, such as multimode fibres, thin-core fibres, PCFs and et al. And low-loss high-strength splice between CMCF and conventional single-mode fibre can be implemented with a commercial fusion splicer. Both the propagation characteristics and operation principle of such a sensor are demonstrated in detail. A sensitivity of ~50.13 pm/°C within temperature range of 30–70 ℃ are experimentally achieved, respectively.