Extending the temperature range of an interferometric fiber sensor using the Vernier effect

The Vernier effect has been commonly used in fiber optic sensors for increasing their sensitivity response. In this work, we propose to use the Vernier spectrum for extending the range of measurement of an interferometric temperature fiber sensor. A proper design of the temperature sensor is proposed to extend the measurement range by generating a Vernier spectrum. This fiber sensor is based on a pair of Fabry-Perot interferometers. A comprehensive model is presented to precisely define the extension of the measurement range of a temperature interferometric fiber sensor. For proof of concept, an extension of the measurement range by approximately 15.5 times is demonstrated, showcasing the efficacy of the proposed approach. Extension of the measurement range was achieved by solely considering the design of the two interferometers forming the sensor. Modeling, simulation, and experimental results are presented to validate the effectiveness of the proposed approach.