title: D-shaped fiber grating refractive index sensor induced by an ultrashort pulse laser.
abstract: The fabrication of fiber Bragg gratings was here demonstrated using ultrashort pulse laser point-by-point inscription. This is a very convenient means of creating fiber Bragg gratings with different grating periods and works by changing the translation speed of the fiber. The laser energy was first optimized in order to improve the spectral properties of the fiber gratings. Then, fiber Bragg gratings were formed into D-shaped fibers for use as refractive index sensors. A nonlinear relationship was observed between the Bragg wavelength and liquid refractive index, and a sensitivity of ∼30  nm/RIU was observed at 1.450. This shows that D-shaped fiber Bragg gratings might be used to develop promising biochemical sensors.
authors.forename: Changrui
authors.initials: C
authors.lastname: Liao
authors.forename: Qiao
authors.initials: Q
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
authors.forename: Shen
authors.initials: S
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: He
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Zhengyong
authors.initials: Z
authors.lastname: Li
authors.forename: Yiping
authors.initials: Y
authors.lastname: Wang