Sensitivity investigation of cascaded abruptly tapered fiber based on the Vernier effect

In this paper, we propose and experimentally demonstrate a sensitivity-enhanced temperature sensor by cascading two non-adiabatic tapered fibers (NATFs) based on the Vernier effect. In addition, we investigate the influence of the presence of the reference arm on the cascaded NATFs and compare the temperature response. The experimental results show that a cascaded NATF configuration in which one NATF acts as a sensing arm and the other acts as a reference arm, achieves a temperature sensitivity of -917p m/^∘ C, which is 13.28 times that of the single NATF (-69p m/^∘ C), while a cascaded NATF configuration in which both NATFs act as a sensing arm attains a temperature sensitivity of 440 pm/°C, which is lower than the configuration with a reference arm. It is confirmed that the synchronous change of the two interferometers will reduce the sensing sensitivity of Vernier effect-based sensors by theory and experiments, and provides guidance for the design of Vernier effect-based sensors.