The influence of key characteristic parameters on performance of optical fiber Fabry–Perot temperature sensor

Extrinsic optical fiber Fabry–Perot (F–P) high temperature sensors using Al2O3 ceramic tubes were fabricated by a microscope equipped with a CCD whose scaleplate has been calibrated using a standard gauge block. The initial cavity length of the F–P sensor, which must be larger than 36 µm, whose output signal is demodulated by the multi-peak method is determined. The temperature measurement range of the sensor is 25 °C–1000 °C. Because the temperature sensitivity of the F–P temperature sensor made by Al2O3 ceramic tubes, whose thermal expansion coefficient is different from that of the fiber, is dependent on the initial cavity length, a low initial cavity length is beneficial in improving sensor sensitivity. Compared with the results of the quartz tube F–P sensor, the temperature sensitivity of the ceramic tube F–P sensor is 10 times larger than that of the quartz tube F–P sensor. Hence, it can be deduced that the ceramic tube F–P sensor is greatly improved compared with the quartz tube F–P sensor.