title: Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating.
abstract: A fiber Bragg grating written in a photosensitive microfiber using KrF excimer laser via a uniform phase mask is demonstrated. We have successfully fabricated two Bragg gratings in microfibers having different diameters. In the reflection spectrum of a microfiber Bragg grating (MFBG), we observed two reflection peaks,which agrees with our numerical simulation results. Compared with the fundamental mode reflection, the higher-order reflection mode is more sensitive to the refractive index (RI) variation of the surrounding fluid due to its larger evanescent field. The measured maximum sensitivity is ~102 nm/RIU (RI unit) at an RI value of 1.378 in an MFBG with a diameter of 6 μm.
authors.affiliation: Wuhan National Laboratory for Optoelectronics and Institute of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Bo
authors.initials: B
authors.lastname: Lin
authors.forename: Swee Chuan
authors.initials: SC
authors.lastname: Tjin
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.forename: Guanghui
authors.initials: G
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Shum
authors.forename: Xinliang
authors.initials: X
authors.lastname: Zhang
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D008904:Miniaturization; D012031:Refractometry / Q000295:instrumentation*; D014159:Transducers