title: Mechanism and characteristics of long period fiber gratings in simplified hollow-core photonic crystal fibers.
abstract: We demonstrate the fabrication of high-quality LPFGs in simplified hollow-core photonic crystal fibers, composed of a hollow hexagonal core and six crown-like air holes, using CO2-laser-irradiation method. Theoretical and experimental investigations indicate that the LPFGs are originated from the strong mode-coupling between the LP01 and LP11 core modes. And a dominant physical mechanism for the mode-coupling is experimentally confirmed to be the periodic microbends rather than the deformations of the cross-section or other common factors. In addition, the LPFGs are highly sensitive to strain and nearly insensitive to temperature, and are promising candidates for gas sensors and nonlinear optical devices.
authors.affiliation: Key Laboratory of Optical Information and Technology, Ministry of Education and Institute of Modern Optics, Nankai University, Tianjin, China.
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Wu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Wang
authors.forename: Yan-ge
authors.initials: YG
authors.lastname: Liu
authors.forename: Tingting
authors.initials: T
authors.lastname: Han
authors.forename: Shuo
authors.initials: S
authors.lastname: Li
authors.forename: Huifeng
authors.initials: H
authors.lastname: Wei