title: Measuring higher-order modes in a low-loss, hollow-core, photonic-bandgap fiber.
abstract: We perform detailed measurements of the higher-order-mode content of a low-loss, hollow-core, photonic-bandgap fiber. Mode content is characterized using Spatially and Spectrally resolved (S2) imaging, revealing a variety of phenomena. Discrete mode scattering to core-guided modes are measured at small relative group-delays. At large group delays a continuum of surface modes and core-guided modes can be observed. The LP11 mode is observed to split into four different group delays with different orientations, with the relative orientations preserved as the mode propagates through the fiber. Cutback measurements allow for quantification of the loss of different individual modes. The behavior of the modes in the low loss region of the fiber is compared to that in a high loss region of the fiber. Finally, a new measurement technique is introduced, the sliding-window Fourier transform of high-resolution transmission spectra of hollow-core fibers, which displays the dependence of HOM content on both wavelength and group delay. This measurement is used to illustrate the HOM content as function of coil diameter.
authors.affiliation: OFS Laboratories, 19 Schoolhouse Road, Suite 105, Somerset, New Jersey 08873, USA. jwn@ofsoptics.com
authors.forename: J W
authors.initials: JW
authors.lastname: Nicholson
authors.forename: L
authors.initials: L
authors.lastname: Meng
authors.forename: J M
authors.initials: JM
authors.lastname: Fini
authors.forename: R S
authors.initials: RS
authors.lastname: Windeler
authors.forename: A
authors.initials: A
authors.lastname: DeSantolo
authors.forename: E
authors.initials: E
authors.lastname: Monberg
authors.forename: F
authors.initials: F
authors.lastname: DiMarcello
authors.forename: Y
authors.initials: Y
authors.lastname: Dulashko
authors.forename: M
authors.initials: M
authors.lastname: Hassan
authors.forename: R
authors.initials: R
authors.lastname: Ortiz
mesh_terms: D000465:Algorithms; D004735:Energy Transfer; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods*; D055100:Optical Fibers