Analyzing the applicability of side-polished fiber Bragg grating tilt sensor using liquid pendulum with controllable angle

Abstract

We developed a simple and novel liquid pendulum-based side-polished fiber Bragg grating (FBG) tilt sensor. Sucrose solution of ∼36 ml with a refractive index (RI) of 1.435 was dispensed into a plexiglass container preprocessed by hydrophobic agent, where the side-polished FBG with a D-shaped polished zone of ∼54 μm depth and ∼15 mm length was attached on the side wall. The liquid level changes caused initial angle-dependent evanescent field interaction with fiber gratings surrounded by the liquid and air, therefore resulting in a wavelength shift of single or dual Bragg peaks related to the effective RI of polished FBG. The sensor exhibited a tilt-induced sensitivity of 131 pm relative to tangent of angle with a linearity of 5.4% in a range of 15° with a controllable lower-limit angle.