Laser-induced suspension of a microbubble in a liquid-filled fiber microcavity for large-range tilt sensing

In this Letter, we propose a compact fiber tilt sensor based on a microbubble suspended in a liquid-filled microcavity at the end of a single-mode fiber. By coupling a single-frequency laser with enough power, the microbubble could suspend in the microcavity due to the Marangoni effect, which constitutes a Fabry-Perot interferometer. When the tilt angle changes, the position of the microbubble changes as well, which causes the variation of the dominant frequency of the interference fringes in the spectrum. The experimental results show that the tilt angle sensitivity of the sensor reaches ${3.64} \times {{10}^{ - 4}}\;{{\rm nm}^{ - 1}}/{\rm Deg}$3.64×10-4nm-1/Deg at a wide sensing range from ${-}{45}^\circ $-45∘ to 45° with a good repeatability.