Ultrasensitive temperature sensor based on optic fiber Fabry–Pérot interferometer with Vernier effect

An ultrahigh sensitivity optic fiber temperature sensor with cascaded two Fabry–Pérot​ interferometers (FPIs) based on the Vernier effect has been fabricated and experimentally demonstrated. One polymer-cavity FPI is used as a sensing FPI and another fiber-cavity is used as a reference FPI to generate the Vernier effect. The experimental results show that the fabricated FPIs sensor has the high temperature sensitivity of −83.130 nm/°C and a high linear response (R-square: 0.9976), which is almost ∼39 times higher than that of an individual polymer-cavity FPI sensor (∼2.080 nm/°C). The stability experiment is also carried out, and the maximal variation of the wavelength shift of the interference fringes is 2.005 nm for a long-term testing. With its advantages of easy fabrication, low cost and small volume, the proposed sensor has significant benefits in terms of various practical applications that need high precision temperature measurement.