In-Fiber Mach-Zehnder Interferometer Based on Three-Core Fiber for Measurement of Directional Bending

Abstract

A highly sensitive directional bending sensor based on a three-core fiber (TCF) Mach-Zehnder interferometer (MZI) is presented in this study. This MZI-based bending sensor was fabricated by fusion-splicing a section of TCF between two single-mode fibers (SMF) with core-offset. Due to the location of the core in the TCF, a bend applied to the TCF-based MZI led to an elongation or shortening of the core, which makes the sensor suitable for directional bending measurement. To analyze the bending characteristics, two types of TCF-based sensors, with the fusion-spliced core located at different positions between the SMFs, were investigated. A swept source was employed in the measurement technique. The experimental results showed that, for the two types of sensors in this setup, the bending sensitivities of the two sensors were 15.36 nm/m−1 and 3.11 nm/m−1 at the bending direction of 0°, and −20.48 nm/m−1 and −5.29 nm/m−1 at the bending direction of 180°. The temperature sensitivities of the two sensors were 0.043 nm/°C and 0.041 nm/°C, respectively. The proposed sensors are compact, versatile, inexpensive to fabricate, and are expected to have potential applications in biomedical sensing.

Fiber Optic Sensors for Vital Signs Monitoring. A Review of Its Practicality in the Health Field

“…In Figure 7, showed some most common configurations on the fiber MZI sensors type, the changes in the microstructure of the fiber are by taper, joints with other fibers, and displacements of the cores between one or more fibers or with multicore fibers, where the fundamental issue is to make a difference of optical methods through the interference. [39,40]. Here are different fiber MZI where we point out: (a) shows an interferometer created through a taper in the optical fiber, the same that is obtained by applying force in opposite directions when an unloading by electrical arc is made to modify the nano structure of optical fiber [41]; (b) shows joints of optical fiber but with a space displacement in the cores, which originates interference [42]; (c) shows joints of several types of optical fiber, where in the first, a fiber Bragg grating type created on a single mode fiber that is joined with an optical fiber with three cores that also hold a concealed knife with another single mode fiber segment [43].…”

“…Reproduced from Refs. [ 19 , 25 , 28 , 32 , 39 , 40 , 56 , 85 , 94 , 95 , 96 , 106 , 107 ] Sensors Journal, Materials Journal, Applied Sciences Journal, Fibers Journal and Journal of Functional Biomaterials of the MDPI. Reproduced from Refs.…”

A Comprehensive Review on the Optical Micro-Electromechanical Sensors for the Biomedical Application

“…The MZI is considered an optical MEMS sensor that was bringing properties such as elongation or shortening of the core made possible by applying force. Overall bending sensitivity of 15.35 and 3.11 nm/m was obtained ( 3 ). MZI is also used to propose the potential measurement of the trajectories of joint angle.…”

Hybrid LPG-FBG Based High-Resolution Micro Bending Strain Sensor

“…Previous papers have increased the sensitivity of FBG Bragg gratings using microstructures through tapering technology [58], and Bragg gratings based on grating configurations [59] have been introduced by previous studies. In addition, various previous studies have improved the maximal function of the Bragg grating sensor and investigated the sensing of various characterizations of the measurement range [60][61][62][63].…”