Hollow-core fiber and method for manufacturing hollow-core fiber

Abstract

A hollow-core fiber includes a hollow region that is a region extending in a longitudinal direction. The hollow region includes a glass structure constituting an optical transmission part provided with a hollow portion, and an outer cladding surrounding the glass structure. When a diameter of a circle having the same area as a total area of a cross section of the glass structure is set to 2a, an average refractive index of the glass structure is set to n1, an average refractive index of the outer cladding is set to n2, a wavelength of light propagating through the optical transmission part is set to λ, and a specific refractive index difference between the glass structure and the outer cladding is set to Δ shown in Equation (1), then n1>n2, and a normalized frequency v shown in Equation (2) is 2.56 or more. [ Formula ⁢ 1 ]  Δ = n ⁢ 1 2 - n ⁢ 2 2 2 ⁢ n ⁢ 1 2 ( 1 ) [ Formula ⁢ 2 ]  v = 2 ⁢ π λ ⁢ an ⁢ 1 ⁢ 2 ⁢ Δ ( 2 )

Dependencies are inferred from the claim text.