title: Geometric definition of the V-parameter in photonic crystal fibers.
abstract: We propose a general geometric definition of the V-parameter in photonic crystal fibers (PCF). We argue that the fundamental modal field in both square-lattice and triangular-lattice PCFs can be approached by certain proper assemblies of the fundamental mode in a one-dimensional planar waveguide. This observation suggests a geometric definition of the effective core radius and the single-mode regime of V≤π/2 in various PCFs. The numerical results imply that the suggestion is valid for all of the one-rod, seven-rod, 19-rod, and 37-rod core triangular-lattice PCFs and the one-rod, nine-rod, and 25-rod core square-lattice PCFs.
authors.forename: Xian-Feng
authors.initials: XF
authors.lastname: Bao
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: Su
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Shu