title: Negligible birefringence in dual-mode ion-exchanged glass waveguide gratings.
abstract: Polarization dependence of UV-written Bragg gratings in buried ion-exchanged glass waveguides is investigated. A polarization-dependent shift in Bragg wavelength of less than 0.02 nm is measured, both for the even and the odd modes of a laterally dual-mode waveguide. The measured wavelength shift corresponds to a waveguide birefringence of the order of 10(-5), which is negligible for most applications in optical communications. It is observed that the UV-induced birefringence is small, within the limits of the measurement accuracy. The thermal stability of the fabricated gratings is also very good. The results are of particular importance for devices considered here since they require a polarization-independent mode-converting waveguide Bragg grating. Polarization-independent performance of these gratings enables the fabrication of a new class of integrated optical devices for telecommunication applications.
authors.affiliation: Optoelectronics Laboratory, Helsinki University of Technology, Espoo, Finland. syliniem@cc.hut.fi
authors.forename: Sanna
authors.initials: S
authors.lastname: Yliniemi
authors.forename: Jacques
authors.initials: J
authors.lastname: Albert
authors.forename: Albane
authors.initials: A
authors.lastname: Laronche
authors.forename: Jose M
authors.initials: JM
authors.lastname: Castro
authors.forename: David
authors.initials: D
authors.lastname: Geraghty
authors.forename: Seppo
authors.initials: S
authors.lastname: Honkanen