title: Coreless side-polished fiber: a novel fiber structure for multimode interference and highly sensitive refractive index sensors.
abstract: A novel fiber structure, coreless side-polished fiber (CSPF), is proposed and investigated to implement multimode interference (MMI) and high sensitive refractive index (RI) sensors. For such CSPF, the part of the cladding and the core of a single-mode fiber are side-polished off so as to make the remained cladding a D-shaped multimode waveguide. The excitation and evolution of MMI in the CSPF are simulated numerically. The simulation results show that the high-order modes excited within the D-shaped multimode waveguide are mainly TE0,1(TM0,1)~TE0,6(TM0,6) modes. Moreover, the RI sensing characteristics and the influences of residual thickness and dip wavelength on the sensitivity are investigated both numerically and experimentally. The experimental results show that the CSPF with a residual thickness of 43.1 μm can reach an ultra-high sensitivity of 28000 nm/RIU in the RI range of 1.442~1.444. It is also found that the sensitivity can be further increased by reducing the residual thickness and choosing the dip at a longer wavelength. Thanks to the ultra-high RI sensitivity and the ease of fabrication, the CSPF could provide a cost-effective platform to build high-performance fiber devices of various functions.
authors.forename: Huazhuo
authors.initials: H
authors.lastname: Dong
authors.forename: Liheng
authors.initials: L
authors.lastname: Chen
authors.forename: Junjie
authors.initials: J
authors.lastname: Zhou
authors.forename: Jianhui
authors.initials: J
authors.lastname: Yu
authors.forename: Heyuan
authors.initials: H
authors.lastname: Guan
authors.forename: Wentao
authors.initials: W
authors.lastname: Qiu
authors.forename: Jiangli
authors.initials: J
authors.lastname: Dong
authors.forename: Huihui
authors.initials: H
authors.lastname: Lu
authors.forename: Jieyuan
authors.initials: J
authors.lastname: Tang
authors.forename: Wenguo
authors.initials: W
authors.lastname: Zhu
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Cai
authors.forename: Yi
authors.initials: Y
authors.lastname: Xiao
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Zhe
authors.initials: Z
authors.lastname: Chen