title: Multicorelike guidance in a triangular-core hollow optical fiber and spectral evolution of its eigenmode degeneracy.
abstract: A unique multicorelike guidance was achieved in a microstructured optical fiber composed of a circular air hole at the center surrounded by a high-index triangular core. Unique spectral evolution of the degeneracy was theoretically investigated using a vectorial finite element method to find a threefold degeneracy in both the fundamental and the first excited modes in the visible range, which evolved to twofold degeneracy as the wavelength increased to IR. Experimental measurements also confirmed evolution of the modal intensity from three spatially isolated patterns confined to individual corners into a supermode combining the three corners.
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea.
authors.forename: Sejin
authors.initials: S
authors.lastname: Lee
authors.forename: Woosung
authors.initials: W
authors.lastname: Ha
authors.forename: Jens
authors.initials: J
authors.lastname: Kobelke
authors.forename: Kay
authors.initials: K
authors.lastname: Schuster
authors.forename: Sonja
authors.initials: S
authors.lastname: Unger
authors.forename: Kyunghwan
authors.initials: K
authors.lastname: Oh