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Tailored fiber Bragg gratings inscribed with a phase mask and a deformed wave front by ultrashort pulses

: Becker, Ria G.; Voigtländer, Christian; Thomas, Jens; Richter, Daniel; Singh, Anshuman; Tünnermann, Andreas; Nolte, Stefan


Honea, Eric C. (Ed.) ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Fiber Lasers IX: Technology, Systems, and Applications : San Francisco, California, USA, January 2012
Bellingham, WA: SPIE, 2012 (Proceedings of SPIE 8237)
ISBN: 978-0-8194-8880-0
Paper 82372H
Conference "Fiber Lasers - Technology, Systems, and Applications" <9, 2012, San Francisco/Calif.>
Conference Paper
Fraunhofer IOF ()
fiber Bragg grating; fiber optics components; ultrafast processes in condensed matter; diffraction grating

We report on the ultrashort pulse inscription of chirped fiber Bragg gratings (FBG) using a constant phase mask and a deformed wave front. To analyze the influence of wave front deformations on the grating period, a numerical model was developed. It is based on a ray optical solution of the diffraction of an arbitrary wave front at a phase mask with a constant period, where the wave front is described by Zernike polynomials. Generally, a plane wave front generates an interference pattern with half the phase mask period. A defocus changes the grating period, while higher order aberrations like coma or spherical aberration yield a chirp along the inscribed grating. Additionally, the grating period depends on the distance of phase mask and fiber. To experimentally deform the wave front of the inscription beam, a cylindrical tuning lens was introduced to the setup. Due to decentering and tilting of the tuning lens, higher order aberrations were generated. Furthermore the fiber was tilted with respect to the phase mask. A chirped FBG with a FWHM bandwidth of 6.2 nm was realized.