title: Leakage coupling of ultrasensitive periodical silica thin-film long-period grating coated on tapered fiber.
abstract: This investigation demonstrates leakage coupling between fundamental-mode and high-order mode resonance based on a periodical silica thin-film long-period grating (TFLPG) that was coated on a tapered fiber when wavelengths longer than the fundamental-mode cutoff were propagated. For the leaky guiding situation, these leakage modes still may exhibit strong mode coupling in the taper with the assistance of the TFLPG when the phase-matched condition is satisfied. An extremely high tuning efficiency of 62.9 nm/°C, which is equivalent to a measurement of sensitivity of approximately 168, 182 nm per refractive index unit, is achieved. To the best of our knowledge, this sensitivity is the highest achieved for a fiber sensor to date.
authors.affiliation: Department of Electro-Optical Engineering, National United University, Miaoli 360, Taiwan. cherry@nuu.edu.tw
authors.forename: Cheng-Ling
authors.initials: CL
authors.lastname: Lee
authors.forename: Zi-Yu
authors.initials: ZY
authors.lastname: Weng
authors.forename: Chuan-Jung
authors.initials: CJ
authors.lastname: Lin
authors.forename: YuanYao
authors.initials: Y
authors.lastname: Lin