title: Fabrication of long-period fiber gratings by twisting a standard single-mode fiber.
abstract: A new method of fabrication of long-period fiber gratings by twisting of a standard single-mode fiber at high temperature is presented. The method relies on the fact that there always exists some core-cladding eccentricity in the optical fiber. Therefore, when the fiber is twisted, its core follows a helicoidal path inside the cladding. The transmission spectrum of the helicoidal long-period fiber grating that is produced contains several dips that correspond to resonances with the fiber cladding modes.
authors.affiliation: Unidade de Optoelectrónica e Sistemas Electrónicos, Instituto de Engenharia de Sistemas e Computadores-Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal. olegivvit@yandex.ru
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Ivanov