Ultrashort pulse inscription of tailored fiber Bragg gratings with a phase mask and a deformed wavefront [Invited]

We report on the inscription of chirped fiber Bragg Gratings (FBGs) with a phase mask and a deformed wavefront using a femtosecond laser. A qualitative model is developed to predict the behavior of the resulting grating period for a deformed wavefront. In addition the quantitative change of the period was simulated based on a ray optical solution of the diffraction behind the phase mask. For deforming the wavefront experimentally a cylindrical tuning lens was used. Tilting of the lens increased the higher order aberrations like coma and spherical aberration, which leads to chirped FBGs. A chirped FBGwith a FWHM bandwidth of 2.5 nm could be realized. The change of the resulting fiber Bragg grating period was measured using a side diffraction setup yielding good agreement with the measured spectra.