Temperature and pressure sensing system of side hole fiber grating based on scanning laser

An optical fiber simultaneous measurement system of temperature and pressure was studied in this report. The fiber optic sensor head is based on fiber Bragg gratings of side hole polarization maintaining fiber. Taking use of its unique double reflection peaks arising from birefringence, simultaneous measurement of temperature and pressure can be achieved. The controls of laser wavelength scanning, acquisitions of spectral data and the data demodulations based on Newton least squares fitting algorithm were highly integrated in one system. Experimental results show that the dual reflection peaks correspond to changes in temperature and pressure with a good linear characteristics, in the temperature range of 10 ∼ 50°C and the pressure range of 0 ∼ 1.2MPa. The wavelength demodulation accuracy of the system is up to 1pm, corresponding to the resolution of temperature and pressure is up to 0.1 °C and 0.1MPa respectively.