ABSOLUTE SINGLE MODE OPTICAL FIBER AND ITS DESIGNING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an absolute single mode optical fiber which is easily manufactured and has a high degree of freedom of design and its designing method. SOLUTION: A cladding part 12 constituting the optical fiber is configured in a photonic crystal structure provided with voids which extend in the extension direction of the cladding part 12 and arranged cyclically in a lattice spacingΛ, and the voids are arranged so as to make an axisymmetric property around the central axis of a core part 11 to be less than three times. The lattice spacingΛof the voids is set so that an effective refractive index of a first mode can be larger than an effective refractive index of the cladding part and also that an effective refractive index of a second mode can be smaller than the effective refractive index of the cladding part in the first mode where the effective refractive index to the wavelength of light propagating through the core part 11 becomes maximum and in the second mode where the effective refractive index becomes the second maximum among a plurality of modes that can exist in an area where the core part 11 and voids adjacently surrounding the core part 11 exist. COPYRIGHT: (C)2004,JPO