Bragg Gratings Written in All->tex<$rm SiO_2$>/tex<and Ge-Doped Core Fibers With 800-nm Femtosecond Radiation and a Phase Mask

Extraordinary stability of anisotropic femtosecond direct-written structures embedded in silica glass

“…In agreement with previously reported results, 12 the index change of the isotropic nonbirefringent structures decreased by a factor of ϳ0.4, with respect to the initial value after heating to 800°C, and finally disappeared after annealing at 1100°C. On the contrary, the birefringent regions were still clearly visible under an optical microscope even after annealing at 1100°C.…”

“…12,13 In this letter, we show the different response to increased temperature displayed by the femtosecond laser written structures of type I_fs and type II_fs, with particular attention to the extraordinary behavior of the structures of type II_fs, whose refractive index change increases with temperature.…”

Selection of fiber-optical components for temperature measurement for satellite applications

“…A grating structure with a modulated refractive index along the fiber axis is written by a UV-excimer laser (193 nm or 248 nm) in a photosensitive fiber [10,11]. Another manufacturing process is the writing of the grating by femto-second infrared (fs-IR) pulses [12,3,9].…”

Femtosecond pulse written fiber gratings: a new avenue to integrated fiber technology

“…If IR light is used for inscription, the band gap of the glass could only be overcome by a multiphoton process. Such gratings are therefore called Type I-IR by some [82]. However, if the inscribing wavelength lies in the UV, one-photon processes compete with nonlinear absorption [83,84].…”

“…In IR-femtosecond pulse written FBGs, significantly strong reflections resulting from Δn 2 up to Δn 4 could be measured [46,82,125]. With longer periods, Fourier orders from Δn 7 to Δn 12 could be exploited for single mode reflection [95].…”