Patent ID: 8938146
Filing Date: 2015-01-20
Classification: G02B

Abstract:
1. A hollow core optical fiber comprising: a core region having a longitudinal axis, a cladding region surrounding said core region, said core and cladding regions forming a care-cladding interface supporting at least one surface mode, said core and cladding regions configured to support and guide the propagation of light in one or more transverse modes of said core region in the direction of said axis, said cladding region including an inner cladding region, the cross-section of said inner cladding region perpendicular to said axis having a periodic spatial variation of its refractive index configured to guide said light by bandgap confinement, said inner cladding region including at least one perturbation region that perturbs the periodicity of said index therein, said at least one perturbation region being configured to resonantly couple said at least one surface mode to at least one transverse mode of said perturbation region, and said perturbation region being configured to suppress at least said surface mode; wherein: said periodic spatial variation having a representative pitch, L, said inner cladding region comprising a majority of holes having diameter d wherein d 1 and d 2 are different, and d and said number of first holes is larger than said number of second holes, and said number of second holes is larger than 3.