Abstract
A pressure-assisted arc discharge method of preparing silicon microbubbles with a glass tube was utilized for decreasing the bubble film’s thickness and improving the bubble’s uniformity. By controlling the arc discharge intensity, discharge time and the position of the fiber carefully, the thickness of the microbubble film was reduced to the micrometer scale. Later, the thin film of the microbubble was transferred to the end the single-mode-fiber/glass-tube structure, for forming the FP (Fabry–Perot) interference cavity. As the thin film is sensitive to the outer pressure, such a configuration could be used for a high-sensitive-pressure measurement. Experimental results show that the sensitivity of this FP (Fabry–Perot) cavity was 6790 pm/MPa when the outer pressure ranges from 100 to 1600 kPa, and the relationship between the structural parameters of the thin film and the outer pressure was theoretically analyzed. Moreover, this special structure made of the end silicon film microbubble is more suitable for high-sensitivity applications.
Highlights
The Fabry–Perot interferometer (FPI) has the advantages of small size and high sensitivity, and it plays an important role in pressure sensing [1,2,3,4]
A diaphragm fiber optic sensor is a kind of sensor based on the Fabry–Perot interferometer structure
The interference spectrum signal was demodulated by optical spectrum analyzer (OSA) (Optical spectrum analyzer)
Summary
The Fabry–Perot interferometer (FPI) has the advantages of small size and high sensitivity, and it plays an important role in pressure sensing [1,2,3,4]. In 2014, Liao et al used expansion arc discharge technology to form a bubble micro-cavity with a film thickness of 500 nm on the end face of the fiber and used it for pressure sensing [5]. Nuclear offset fusion splicing technology was used in the manufacturing process, to reduce the fringe angle, so that the detection limit of sensor parts was lowered to 4.81 kPa. In this study, we used the optimized arc discharge technology to prepare the end-face bubble micro-cavity and prepare the fiber end-face uniform microbubble cavity with a thickness of micrometer scale. The end-face film of the bubble micro-cavity was transferred to the end face of the glass tube, to form the fiber FPI and apply to the field of pressure sensing. The relationship between the structural parameters and the pressure response of thin films is theoretically and experimentally demonstrated
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