A Fabry-Pérot (F-P) interference optical fiber pressure temperature composite sensor based on all sapphire substrateis researched and fabricated for high temperature applications. Micro-electro-mechanical systems (MEMS) technologyand atomic direct bonding technology are used to fabricate F-P pressure temperature composite sensing cavity and thenpackaged to form core components of the sensing probe. The high-temperature fiber is used as transmission medium ofoptical signal. Length of pressure sensing cavity is 104.5μm, length of temperature sensing cavity is 434μm. Sensingcharacteristics test on chip is carried out, and pressurization tests on sensor from room temperature to 400°C areperformed. The experimental results show that pressure chip of 5MPa can distinguish pressure of 0.17kPa, the relativeresolution can reach 33ppm, and temperature cavity length fluctuate ±0.1nm within 678s, which is equal to 0.05°Ctemperature error. Performance index of sensor in temperature range of the whole is good. This research provides strongsupport for extrinsic optical fiber sensor based on sapphire composite F-P cavity using for precise and stable pressureand temperature measurement in high temperature environment.
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