Strain and temperature discrimination using a fiber Bragg grating and multimode interference effects

A fiber optic sensor capable of measuring strain and temperature simultaneously is proposed and demonstrated. The key component is a no-core fiber (NCF) followed by a fiber Bragg grating (FBG), which helps to resolve the crosstalk issue. The interference fringe of the NCF and the Bragg wavelength of the FBG would shift with the variation of strain and temperature. Since the NCF and the FBG have different sensitivity responses to strain and temperature, it is possible to measure strain and temperature simultaneously by simply monitoring the wavelength shifts. The experimental results show that the strain sensitivity and the temperature sensitivity of the sensor are 1.19 pm/με and 12.8 pm/°C, respectively. The prototype might be attractive due to its low fabrication cost and simple configuration, which are desirable features in dual-parameter measurement.