Optical Fiber Inclinometer Based on a Fiber Taper Cascading a Peanut-Shape Structure

An optical fiber inclinometer applying modal interference based on an abrupt tapering cascading a peanut-shape configuration is proposed. The abrupt taper splits part of the core mode into cladding modes and the interference occurs when the peanut-shape recombines the cladding modes and core mode together. Four inclinometers with different lengths have been fabricated and characterized, and the high sensitivities of -1.76 and -4.49 nm/° are obtained in the angle range of 0°-3° and 3°-6.66°, respectively.