title: Contra-directional two-beam coupling by use of a single input beam in an iron-doped lithium niobate multimode fiber.
abstract: Experimental results are presented for 1,800 contra-directional two-beam coupling (TBC) measurements in a single crystal fiber of LiNbO8:Fe using a single incident beam and its Fresnel reflection off the back surface of the fiber. To our knowledge, this is the first time that volume gratings have been written in a fiber using this beam coupling geometry. At small f-numbers, the TBC efficiency has been predicted to decrease in bulk LiNbO3:Fe due to the erasure of the weak gratings by the dark conductivity. We present experimental results validating the published theory and show experimentally that confinement of the interfering beams in a fiber geometry overcomes this limitation.
authors.affiliation: Air Force Research Laboratory Materials and Manufacturing Directorate/ MLPJ, WPAFB, Ohio 45433, USA. Dean.Evans@wpafb.af.mil
authors.forename: D R
authors.initials: DR
authors.lastname: Evans
authors.forename: M A
authors.initials: MA
authors.lastname: Saleh
authors.forename: T J
authors.initials: TJ
authors.lastname: Bunning
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.forename: R S
authors.initials: RS
authors.lastname: Meltzer
authors.forename: W M
authors.initials: WM
authors.lastname: Yen
authors.forename: S
authors.initials: S
authors.lastname: Guha