JPS5697304A - Graded refractive index distribution type optical fiber - Google Patents

Abstract

PURPOSE:To introduce a large luminous flux with good efficiency into optical fibers by forming self-convergent fibers which have prescribed refractive indexes in a radial direction and are extremely fine in the intermediate part, and continuously changing the radius while maintaining the product of intrinsic constant and the square of radius constant near both ends. CONSTITUTION:Rod lenses 13, 23 of a number of stages made by using such self- convergent type optical fibers of which the refractive indexes in a radial direction satisfy n=n0(1-0.5Ar<2>) where the radial of optical fibers are defined as (r) and the refractive indexes on the axis as n0, and connecting these in a manner that the product of intrinsic constant A and the square of radius R satisfies fixed conditions, are connected to a fine rod lens 33. Or equally good results is obtained by connecting a pair of rod lenses 14, 13 which are made by extending one rod lens, in order to decrease the difference of the surface level of the rod lenses 13, 23. Thereby, a large luminous flux is introduced into the fiber with good efficiency.