title: High group birefringence in air-core photonic bandgap fibers.
abstract: A numerical investigation of group birefringence is carried out on a recently reported highly birefringent hollow-core photonic bandgap fiber by use of an efficient vector finite-element method. The hollow fiber core has an area as large as that of approximately four airholes in the cladding region and assumes a rhombic shape with round corners, and the airholes in the cladding region are hexagonal and provide a high air-filling fraction. Numerical results show very high group birefringence of the order of 10(-2) and phase birefringence of the order of 10(-3).
authors.affiliation: Hokkaido University, Sapporo 060-0814, Japan.
authors.forename: M Shah
authors.initials: MS
authors.lastname: Alam
authors.forename: Kunimasa
authors.initials: K
authors.lastname: Saitoh
authors.forename: Masanori
authors.initials: M
authors.lastname: Koshiba