Micro-aspheric collimator lens

This invention relates to methods of and apparatus for connecting optical fibers. In particular, it relates to lenses to couple light from one fiber into another, and to the design of such lenses so as to permit improved packaging of optical fibers, lenses, and related components. Apparatus for coupling light from one optical fiber into another includes a pair of molded plano-convex lenses. Each lens has an aspheric surface and a flat surface. The aspheric surfaces have a conic constant between −0.6 and −0.3, where the conic constant is chosen so as to give optimal coupling efficiency from a collimated beam input on the aspheric surface into an optical fiber located near the flat surface. The pair of lenses are separated by a distance approximately equal to the sum of the focal lengths of the lenses. Light from an optical fiber placed near the focal plane of one of the pair of lenses is focused into an optical fiber placed near the focal plane of the other of the pair of lenses.