HOLE ASSIST TYPE HOLEY FIBER AND LOW BENDING LOSS MULTIMODE HOLEY FIBER

摘要

A hole assist type holey fiber (HAHF) allowing low bending loss LB and short cutoff wavelength λC to be compatible with each other. The HAHF comprises a core part (11) with a refraction factor higher than that of a clad part, a clad part (12) around the core part (11), and a plurality of vacancies formed in the clad part while surrounding the core part. The HAHF is characterized in that the vacancies are formed in two of inner and outer layers, the quantity of the vacancies in the inner vacancy layer is equal to that in the outer vacancy layer, the outer vacancies (17) are disposed at positions where the inner vacancies (16) are not disposed as viewed from the center of the core part, the vacancies forming each of the vacancy layers have a same diameter, a distance Λ1 between the center of the core part and the centers of the inner cavities and a distance Λ2 between the center of the core part and the centers of the outer vacancies has a relation of Λ1 Λ2, and an inner cavity diameter d1 and an outer cavity diameter d2 has a relation of d1 ≤ d2.