An all-fiber inclination sensor with self-tunable sensitivity and range based on the light-modulated microbubble

An all-fiber inclination sensor with self-tunable sensitivity and range based on the light-modulated microbubble is proposed. The sensor structure is formed by sealing a microbubble in the ethanol-filled microcavity. The end face of the single-mode fiber and the front face of the microbubble form a Fabry-Perot interferometer (FPI). The thermal Marangoni force (TMF) is caused by the temperature difference between the two ends of the microbubble when the light source is coupled into the structure. The microbubble deviates from the balance position at different inclination angles under the effect of TMF and buoyancy force, which can be used for inclination monitoring. Meanwhile, the deviation distance can be modulated by the power of light source, which means that the sensitivity and range of the inclination sensor can be adjusted only by changing the power of the sensor light source according to the actual needs. The results show that the inclination sensitivity can be adjusted in the range of 0.33 nm/Deg∼2.87 nm/Deg. The proposed all-fiber optic inclination sensor with self-tunable ability solves the contradiction between the high sensitivity and the large monitoring range in spectrum wavelength demodulation.