High-sensitivity strain sensor with antiresonance suppression based on the Vernier effect

A fiber-optic strain sensor with antiresonance suppression was proposed, and sensor sensitization was achieved by constructing a simulated reference interferometer (SRI) using the Vernier effect. In the capillary-based Fabry–Perot interferometer (FPI), antiresonance resulted in uneven contrast of the reflection spectrum, which could not meet the conditions for the use of the Vernier effect. In addition to controlling the length of the capillary to below the critical length to overcome this problem, antiresonance could be suppressed by increasing the thickness. A strain sensitivity of 14.58 pm/με, which is 7.15 times higher than the strain sensitivity of a single sensing interferometer, was achieved using the antiresonance-suppressed FPI as a sensing interferometer and modulating it with the constructed SRI. In addition, tunable sensitivities of 22.36 and 32.83 pm/με were obtained by only changing the parameters of SRI instead of remaking the reference interferometer. The sensor realized the Vernier effect with only one interferometer. It has the advantages of online control sensitivity, simple structure, and low cost and has potential important applications in the field of strain measurement.