Simultaneous discrimination of strain and temperature using dual-gratings in one fiber

An alternate solution to measure the stain and temperature simultaneously is proposed. In the acknowledged techniques, the most simple way of measuring stain and temperature simultaneously is to write fiber Bragg gratings (FBGs) in two fibers with different diameters. However, this way has a disadvantage of weak joint and high loss of splicing point which cannot be ignored. We present a new method to overcome this disadvantage by fabricating this dual-gratings sensing structure in one fiber, thus, the strength of this sensor is greatly increased and the transmission loss is nearly zero. This sensor is calibrated in a temperature range from 20 °C to 70 °C and in a strain range from 0 to 900 μɛ. The temperature sensitivity coefficients of these dual-gratings are completely consistent, and at the same time the strain sensitivity coefficients are flexible which can be adjusted by controlling the diameter of fiber. The reflection peak wavelengths of this sensor have a good linear relationship with strain and temperature and match the theoretical calculation well in our experiments.