title: Writing Bragg Gratings in Multicore Fibers.
abstract: Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.
authors.affiliation: Sydney Institute for Astronomy, School of Physics, University of Sydney; elindley@physics.usyd.edu.au.
authors.forename: Emma Y
authors.initials: EY
authors.lastname: Lindley
authors.affiliation: Sydney Institute for Astronomy, School of Physics, University of Sydney; Institute of Photonics and Optical Science, School of Physics, University of Sydney.
authors.forename: Seong-Sik
authors.initials: SS
authors.lastname: Min
authors.affiliation: Sydney Institute for Astronomy, School of Physics, University of Sydney; Institute of Photonics and Optical Science, School of Physics, University of Sydney.
authors.forename: Sergio G
authors.initials: SG
authors.lastname: Leon-Saval
authors.affiliation: Sydney Institute for Astronomy, School of Physics, University of Sydney; Institute of Photonics and Optical Science, School of Physics, University of Sydney; Center for Ultrahigh Bandwidth Devices for Optical Systems, School of Physics, University of Sydney; Australian Astronomical Observatory.
authors.forename: Nick
authors.initials: N
authors.lastname: Cvetojevic
authors.affiliation: Australian Astronomical Observatory.
authors.forename: Jon
authors.initials: J
authors.lastname: Lawrence
authors.affiliation: Sydney Institute for Astronomy, School of Physics, University of Sydney; Australian Astronomical Observatory.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Ellis
authors.affiliation: Sydney Institute for Astronomy, School of Physics, University of Sydney; Institute of Photonics and Optical Science, School of Physics, University of Sydney.
authors.forename: Joss
authors.initials: J
authors.lastname: Bland-Hawthorn
mesh_terms: D004741:Engraving and Engravings; D004867:Equipment Design; D005336:Fiber Optic Technology / Q000295:instrumentation / Q000379:methods*; D005898:Glass; D007909:Lenses; D008027:Light; D055096:Optical Devices; D012031:Refractometry / Q000295:instrumentation / Q000379:methods