Abstract: A novel plate diaphragm based FBG sensor is proposed to measure temperature and pressure simultaneously. Two
FBGs are attached radially and circumferentially to a metal diaphragm respectively, and when temperature and pressure change, the peak wavelength of the FBGs will shift. The peak wavelength shifts of the two FBGs induced by temperature are
approximately the same when the different pressures are exerted on the sensor. The peak wavelength difference depends only on the exerted pressure. So the simultaneous measurement of the temperature and pressure can be carried out. The line
arity of the sensor is good. The measurement ranges of temperature and pressure are 40℃～110℃ and 0～6MPa, and the temperature and pressure measurement errors are less than 1℃ and 0. 2MPa respectively.

Key words: guided wave and fiber optics, optical fiber sensing, in-fiber Bragg grating sensing, sensitivity of the sensor