title: Ultraviolet-light photosensitivity in Er(3+)-Ge-doped optical fiber.
abstract: Light-induced refractive-index change in Er(3+)-Ge-doped optical fiber is reported for the first time to the authors' knowledge. Evidence of the change is observed when UV light (lambda = 249 nm) irradiates one arm of an unbalanced Mach-Zehnder interferometer made from Er(3+)-Ge-doped fiber. From a measurement of the change in the spectral response of the interferometer with UV exposure, the change in fiber core index as a function of wavelength is determined. The equilibrium change in core index is found to vary between 2.3 x 10(-5) and 3.7 x 10(-5) over the measured wavelength region of 800 to 1700 nm. Also for the first time to our knowledge, fused couplers made of Er(3+)-doped fiber are reported. These identical fiber couplers are used in a novel all-fiber unbalanced Mach-Zehnder interferometer.
authors.forename: F
authors.initials: F
authors.lastname: Bilodeau
authors.forename: D C
authors.initials: DC
authors.lastname: Johnson
authors.forename: B
authors.initials: B
authors.lastname: Malo
authors.forename: K A
authors.initials: KA
authors.lastname: Vineberg
authors.forename: K O
authors.initials: KO
authors.lastname: Hill
authors.forename: T F
authors.initials: TF
authors.lastname: Morse
authors.forename: A
authors.initials: A
authors.lastname: Kilian
authors.forename: L
authors.initials: L
authors.lastname: Reinhart