Simultaneous measurement of down-hole high pressure and temperature with a bulk-modulus and FBG sensor

A free active element bulk-modulus-based fiber Bragg grating (FBG) sensor for down-hole pressure and temperature measurement is presented. With a differential measurement method and an isosceles triangle cantilever structure, problems of cross-sensitivity and chirped-signal in FBG sensors are solved. Simulation results indicate that the measurement sensitivity in measuring pressure and temperature is estimated to be /spl sim/8.5 pm/MPa in a range from standard atmosphere pressure to 100 MPa and /spl sim/27.5 pm//spl deg/C from 20 to 200/spl deg/C, respectively.