Extending the range of measurement and the sensitivity response of Fabry-Perot interferometric sensors

Two-wave interference fiber interferometers have a higher sensitivity response when they have longer optical path difference, which in exchange produce a short interference period; and this period ultimately limits the range of measurement due to the 2π phase ambiguity. In this work, a novel methodology is proposed to increase both the measurement range of an interferometric fiber sensor and its sensitivity response. In a first stage, for proof of concept, the measurement range is increased 15 times, which translates to an increase of measurement range from 23°C to 360°C. Furthermore, in a second stage, the Vernier effect is used to increase the sensitivity response by means of a virtual cavity used as a reference cavity. Here, the sensitivity response was increased by a factor of 15. This two-stage methodology is described by modeling and simulation, and demonstrated with experimental results. The importance of the methodology lies in the optimization of the performance of interferometric fiber sensors.