Etched Fiber Bragg Grating-Based Novel Tilt Sensor Employing Effective Refractive Index Induced Intensity Modulation Mechanism

Etched fiber Bragg grating (FBG)-based temperature-insensitive, simple, all-optical tilt sensor design, employing effective refractive index (RI) induced intensity modulation (instead of traditional strain modulation), is proposed and theoretically demonstrated. The etched FBG splits into two distinct gratings when partially immersed in a liquid. Applied tilt modulates the length of etched FBG immersed into a liquid, which, in turn, modulates the characteristic reflection spectrum of both the sections (exposed to liquid and to the air). The theoretical maximum sensitivity of the proposed sensor comes out to be 1.20 dB°. Further, the sensor exhibits the ability to quantify both the magnitude and direction of inclination relative to the horizontal plane across the designated dynamic range of ±10°.