Parallelized fiber Michelson interferometers with advanced curvature sensitivity plus abated temperature crosstalk

In this Letter, we proposed a super sensitive optic-fiber curvature sensor with ultra-low temperature crosstalk based on Vernier effect and achieved it experimentally. This sensor composes a pair of parallelized 2CFMIs (2-core-fiber Michelson interferometers) in similar lengths, both ofwhich are involved sensing, but there is a rotation angle between their cross-sections. When the rotation angle approaches 180 degrees, the magnification factor for curvature sensitivity is doubled compared with conventional Vernier effect, while for temperature it is always 1. Therefore, advanced curvature sensitivity and abated temperature crosstalk can be realized simultaneously when demodulating Vernier envelops. The experiment results indicate that the curvature sensitivity of this sensor reached 214.533 nm/m(-1), and temperature crosstalk was as low as 0.000276 m(-1)/degrees C. The fabrication process is extremely flexible and repeatable, and the magnification factor of Vernier effect could be controlled conveniently. (C) 2020 Optical Society of America