title: Localized waveguide formation in germanosilicate fiber transmitting femtosecond IR pulses.
abstract: Transmission of intense femtosecond 825 nm pulses progressively produces a waveguide at the entrance of a heavily Ge-doped silicate fiber. The waveguide behaves as a multimillimeter long-fiber bandpass filter that scatters away light with wavelengths shorter or longer than 850 nm. This phenomenon has been correlated with the ~800 nm photosensitivity producing type I-IR fiber Bragg gratings in side-written lightly Ge-doped silicate fibers and low-loss waveguides in pure silica bulk glass. A model incorporating color center formation is proposed to understand the underlying mechanism.
authors.affiliation: Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Haohua
authors.initials: H
authors.lastname: Tu
authors.forename: Yee Lin
authors.initials: YL
authors.lastname: Koh
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Marks
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Boppart