Simultaneous Measurement of Gas Pressure and Temperature Sensor Based on F-P Interference Using Hollow Core Bragg Fiber

An optical fiber Fabry-Perot interferometer (FPI) sensor offering simultaneous measurement of temperature and pressure is proposed. This sensor is constructed by fusion splicing a single-mode fiber-hollow core Bragg fiber-single-mode fiber (SMF-HCBF-SMF) structure. The HCBF serves as a pressure-sensitive unit on which gas channels are realized by femtosecond laser machining. The last segment of the SMF serves as a temperature-sensitive unit. The fast Fourier transform-minimum mean square error (FFT-MMSE) algorithm demodulates the sensor's optical cavity lengths to realize the temperature and pressure measurement in the temperature range of 25 degrees C-600 degrees C. Experiments demonstrate that the sensor exhibits high linearity. The sensor's pressure sensitivity decreases as temperature increases. At 25 degrees C and 600 degrees C, the pressure sensitivities are 158.3 and 51.9 nm/MPa, and the temperature sensitivity is 3.8 nm/ degrees C. The pressure full-scale error is only 4% across the entire temperature range when using the temperature-pressure decoupling calculation method. The high-temperature and high-sensitivity characteristics of the proposed sensor highlight its potential for monitoring gas pressure in extremely high-temperature environments.