Abstract: A light branching and coupling device, having a light focusing transmission body, in which the refractive index distribution of the body gradually decreases from the center towards the periphery of the body in a cross-section thereof, said cross-section being perpendicular to the center axis of the body. The light focusing transmission body has a length substantially equal to a positive integral multiple of 1/4 pitch with a reflective surface positioned from an end face of the body at a predetermined distance substantially equal to an odd number multiple of 1/4 pitch. Light incident on one of two end faces perpendicular to the center axis of the body propagates undulatingly to the other end face at a predetermined pitch.

Abstract: The invention contemplates an improved means for coupling plural optical fibers to a single optical fiber, whereby coupling losses may be held to relatively low magnitude. Each of the plural optical fibers is fitted to a first end of an elongate light-transmitting body having an elongate body axis about which the refractive index decreases approximately proportional to the square of the distance from the axis, and these bodies are grouped with their body axes is close and substantially parallel array. The opposite ends of the light-transmitting bodies all spaced from and face the end of the single optical fiber, with the optical axis of said single end aligned with the elongation of the group; and an optical lens is placed on the optical axis between the group and the single-fiber end, with the latter near the focal plane of the lens.