Femtosecond laser etching based sapphire fiber Fabry-Perot sensor and manufacturing method thereof

Abstract

The invention discloses a femtosecond laser etching based sapphire fiber Fabry-Perot sensor and a manufacturing method thereof. The sensor structure comprises a sapphire fiber (1), a quartz fiber (5)and a heterogeneous fiber fusion splice point (6) connecting the two fibers. The tail end of the sapphire fiber (1) has a Fabry-Perot microcavity (2) processed by femtosecond laser etching. Two reflected lights generated by a first reflecting surface (3) and a second reflecting surface (4) of the Fabry-Perot microcavity (2) interfere and generate an interference signal (11). When the ambient temperature changes, the cavity length of the Fabry-Perot microcavity (2) and the refractive index of a material change, and the optical path difference between the two reflected light changes accordingly,thus causing a change of the interference signal (11). The Fabry-Perot optical path difference is obtained by demodulating the interference signal, thereby obtaining a measured temperature. The invention has the characteristics of theoretical innovation, small size and strong environmental adaptability, which can be used for high temperature precision sensing in a narrow measurement environment.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a miniaturized sapphire optical fiber high temperature sensor manufactured based on a femtosecond laser precision etching process. Background technique [0002] The high-temperature sensing technology based on sapphire fiber plays an important role in the field of high-temperature monitoring due to its oxidation resistance, high precision, anti-electromagnetic interference, and miniaturization. [0003] In recent years, various types of sapphire fiber optic sensors have been proposed to achieve extremely high temperature (above 1000°C) measurements, such as fiber grating type, blackbody radiation type, and fiber-optic Fapper type. Among them: (1) The sapphire fiber grating sensor is limited by the large numerical aperture of the sapphire fiber, the mode interference is serious, and the measurement accuracy is lower than other methods. (2) The black body radiation t...

AI Technical Summary

Problems solved by technology

Among them: (1) The sapphire fiber grating sensor is limited by the large numerical aperture of the sapphire fiber, the mode interference is serious, and the measurement accuracy is lower than other methods

(2) The black body radiation type sapphire fiber sensor is based on Planck's black body radiation law, and has good temperature measurement accuracy in the high temperature region (600-1600°C), but due to the significant reduction of the radiation power in the low temperature region, the signal-to-noise ratio below 600°C Extremely fast attenuation, limited temperature measurement range, can only be used for temperature monitoring in high temperature section

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