FIBER FOR OPTICAL TRANSMISSION

摘要

PURPOSE:To make wide-band transmission possible by providing three clad layers on the outside circumference of a core part and specifying the thickness and the refractive index of the first clad layer. CONSTITUTION:The first clad layer 2'' having a refractive index equal to that of the outside edge of a core part 1 and a thickness of 1/100-1/20 of the core diameter is provided around the core part 1 having a refractive index distribution approximating a square-law distribution, and the second clad layer 3' having a refractive index lower than that of the first clad layer 2'' is provided around the first clad layer 2'', and the third clad layer 4 having a refractive index higher than that of the second clad layer 3' is provided around the second clad layer 3'. Since it is sufficient if group delay times of all modes are coincident with one another in a propagation mode region and a leak mode region connected to the propagation mode region for the purpose of attaining a wide band, a wide band is attained in the range where a thickness (d) of the first clad layer 2'' satisfies 1/(100D)