Experimental Demonstration of a Simple Displacement Sensor Based on a Bent Singlemode-Multimode-Singlemode (SMS) Fiber Structure

A simple displacement sensor based on a bent singlemode-multimode-singlemode (SMS) fiber structure is proposed and experimentally investigated. The sensor offers a wider displacement range, not limited by the risk of fiber breakage, as well as a three-fold increase in displacement sensitivity by comparison with a straight SMS structure sensor. This sensor can be interrogated by either an optical spectral analyzer (OSA) or a ratiometric interrogation system: (1) if interrogated by an OSA assuming a resolution of 1 pm, it has a sensitivity of 28.2 nm for a displacement measurement range from 0 to 280 μm; (2) if interrogated by a ratiometric interrogation system, it has worst and best case resolutions of 556 and 38 nm respectively, for a displacement measurement range from 0 to 520 μm