A high-sensitivity curvature mini-two-path MZI fiber sensor based on a four-core fiber

Abstract

We propose and demonstrate a high curvature sensitivity fiber sensor with a mini-two-path Mach-Zehnder interferometer (MTP-MZI) structure based on four-core fiber (FCF). A simple arc discharge technology is used to fabricate the MTP-MZI, where the sensing path is an in-line MZI (IMZI) structure that directly sandwiched the FCF between two sections of coreless fiber (CLF), and the reference path is a single-mode fiber (SMF) only. When the curvature changes from 0 m⁻¹ to 0.101045 m^-1, the IMZI sensor has a maximum curvature sensitivity of 57.29 dB/m⁻¹, while the MTP-MZI sensor has a sensitivity of 108.29 dB/m⁻¹, the curvature sensitivity has been improved by 1.89 times, which is the highest intensity-modulated curvature sensitivity based on multi-core fiber, to the best of our knowledge. The comparable experiment illustrated that the MTP-MZI structure can effectively enhance the sensor's sensitivity and provide an effective method to prepare a good-performance sensor with low-cost, miniaturized, and simple requirement technology.