title: Demonstration of coupling to symmetric and antisymmetric cladding modes in arc-induced long-period fiber gratings.
abstract: The symmetry of cladding modes excited in microbend and arcinduced long-period fiber gratings is investigated. An optimization technique is developed to determine the fiber parameters and to associate grating resonances with cladding modes of a particular symmetry. Using this optimization procedure, we show that the gratings induced in a standard fiber by arc discharges and microbends couple light to the antisymmetric cladding modes. In the case of a boron-germanium codoped fiber, the cladding modes excited by arc-induced gratings are found to be symmetric. Measurements of the near-field intensity distribution of cladding modes confirm the mode symmetry ascertained by the optimization technique.
authors.forename: Gaspar
authors.initials: G
authors.lastname: Rego
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Ivanov
authors.forename: Paulo V S
authors.initials: PV
authors.lastname: Marques