title: Bend-insensitive distributed sensing in singlemode-multimode-singlemode optical fiber structure by using Brillouin optical time-domain analysis.
abstract: We propose a bend-insensitive distributed Brillouin optical fiber sensing by using a singlemode-multimode-singlemode optical fiber structure for the first time to the best of our knowledge. The sensing fiber is a graded-index multimode fiber (GI-MMF) sandwiched by two standard single-mode fibers (SMFs) with central-alignment splicing at the interface between GI-MMF and SMF to excite the fundamental mode in GI-MMF. The sensing system can resist a minimal bend radius of 1.25mm while maintain the measurement performance, with which the measured coefficients of strain and temperature are 421.6MHz/% and 0.826MHz/°C, respectively. We also demonstrate that the higher-order modes excited in GI-MMF can be easily influenced by bending, so that exciting the fundamental mode is essential for bend-insensitive distributed sensing.
authors.forename: Pengbai
authors.initials: P
authors.lastname: Xu
authors.forename: Yongkang
authors.initials: Y
authors.lastname: Dong
authors.forename: Juwang
authors.initials: J
authors.lastname: Zhang
authors.forename: Dengwang
authors.initials: D
authors.lastname: Zhou
authors.forename: Taofei
authors.initials: T
authors.lastname: Jiang
authors.forename: Jinlong
authors.initials: J
authors.lastname: Xu
authors.forename: Hongying
authors.initials: H
authors.lastname: Zhang
authors.forename: Tao
authors.initials: T
authors.lastname: Zhu
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Lu
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Bao