Abstract

A novel low-cost, compact, assembly-free and sensitive optical fiber curvature sensor is presented. This device consists of an off-axis positive refractive index modified zone (PRIMZ), induced by a direct femtosecond laser, written in a single-mode fiber (SMF) core. The PRIMZ transforms the original SMF section into a few-mode fiber (FMF). As a result, the whole fiber forms an assembly-free “SMF-FMF-SMF” sandwich Mach–Zehnder interferometer. When the device is bent, a direction-dependent spectral shift of the interference pattern is produced. The sensitivity of the sensor is up to 2.53 and $2.24\mathrm{nm}/{\mathrm{m}}^{-1}$ for the 0° and 180° orientations in a wide bend range (from 0 to $4{\mathrm{m}}^{-1}$). In addition, the device is immune to the surrounding refractive index and has a low-temperature crosstalk, which makes it very attractive for practical structural monitoring applications.

© 2018 Optical Society of America

Ultra-compact all-in-fiber-core Mach–Zehnder interferometer

Pengcheng Chen, Xuewen Shu, and Kate Sugden
Opt. Lett. 42(20) 4059-4062 (2017)

Fiber-optic bending vector sensor based on Mach–Zehnder interferometer exploiting lateral-offset and up-taper

Shanshan Zhang, Weigang Zhang, Shecheng Gao, Pengcheng Geng, and Xiaolin Xue
Opt. Lett. 37(21) 4480-4482 (2012)

Femtosecond laser inscribed straight waveguide in no-core fiber for in-line Mach–Zehnder interferometer construction

W. W. Li and D. N. Wang
Opt. Lett. 43(14) 3405-3408 (2018)

Intensity-modulated directional torsion sensor based on in-line optical fiber Mach–Zehnder interferometer

Qinjiang Fu, Jingdong Zhang, Chuancan Liang, Iroegbu Paul Ikechukwu, Guolu Yin, Lei Lu, Yifan Shao, Liu Liu, Dongxiao Liu, and Tao Zhu
Opt. Lett. 43(10) 2414-2417 (2018)

Highly sensitive temperature sensor based on an ultra-compact Mach–Zehnder interferometer with side-opened channels

Ming Deng, Leiguang Liu, Yong Zhao, Guolu Yin, and Tao Zhu
Opt. Lett. 42(18) 3549-3552 (2017)