title: Influence of depressed-index outer ring on evanescent tunneling loss in tapered double-cladding fibers.
abstract: A tapered fiber with a depressed-index outer ring is fabricated and dispersion engineered to generate a widely tunable (1250-1650 nm) fundamental-mode leakage loss with a high cutoff slope (-1.2 dB/nm) and a high attenuation for stop band (>50 dB) by modification of both waveguide and material dispersions. The higher cutoff slope is achieved with a larger cross angle between the two refractive index dispersion curves of the tapered fiber and surrounding optical liquids through the use of depressed-index outer ring structures in double-cladding fibers.
authors.affiliation: Department of Electro-Optical Engineering, National United University, Miaoli 360, Taiwan. nkchen@nuu.edu.tw
authors.forename: Nan-Kuang
authors.initials: NK
authors.lastname: Chen
authors.forename: Kuei-Chu
authors.initials: KC
authors.lastname: Hsu
authors.forename: Shien-Kuei
authors.initials: SK
authors.lastname: Liaw
authors.forename: Yinchieh
authors.initials: Y
authors.lastname: Lai
authors.forename: Sien
authors.initials: S
authors.lastname: Chi