Strain sensor based on gourd-shaped single-mode-multimode-single-mode hybrid optical fibre structure

A fibre-optic strain sensor based on a gourd-shaped joint multimode fibre (MMF) sandwiched between two single-mode fibres (SMFs) is described both theoretically and experimentally. The cladding layers of the two MMFs are reshaped to form a hemisphere using an electrical arc method and spliced together, yielding the required gourd shape. The gourd-shaped section forms a Fabry-Perot cavity between the ends of two adjacent but non-contacting multimode fibres' core. The effectiveness of the multimode interference based on the Fabry-Perot interferometer (FPI) formed within the multimode inter-fibre section is greatly improved resulting in an experimentally determined strain sensitivity of -2.60 pm/mu epsilon over the range 0-1000 mu epsilon. The sensing characteristics for temperature and humidity of this optical fibre strain sensor are also investigated. (C) 2017 Optical Society of Americ

High sensitivity temperature sensor based on singlemode no-core-singlemode fibre structure and alcohol

A high sensitivity temperature sensor based on a singlemode-no-core-singlemode (SNCS) fibre structure and surrounded with alcohol within a silica capillary is described. In this investigation, no-core fibre (NCF) is used as the multimode waveguide and alcohol is chosen as the temperature sensitive medium. By packaging the alcohol solution with a short length of NCF enclosed within a silica capillary, the surrounding temperature can be detected by monitoring the variations of transmission loss at a specific wavelength. The theoretical analysis predicts this temperature sensor can provide high sensitivity, and the experimental results support this. The maximum temperature sensitivity of the sample is 0.49 dB/°C with a potential temperature resolution of 0.02 °C at the operating wavelength of 1545.9 nm. In addition, the repeatability and response time of the sensor of this investigation are investigated experimentally