Abstract: In accordance with the disclosed invention, a first group of optical fiber waveguides is spliced to a second, similar group of optical fiber waveguides using a unique foldable holder. The holder illustratively comprises a relatively thin wafer formed of a bendable material, such as a plastic or metal, and includes first and second sections disposed about a centrally extended fold line. Each section of the holder includes a plurality of grooves laterally spaced in a parallel relation symmetrically about the fold line for receiving and aligning the individual fibers in each fiber group to be spliced. To achieve the desired splice, the fibers in a first group are placed and then fixed in the grooves of the first section of the holder, while the fibers in a second group are placed and then fixed in the grooves of the second section of the holder.

Abstract: Particular apparatuses implement a method of breaking a rod of brittle material, such as a glass optical fiber, so as to yield a mirrorlike surface across the entire rod end. A decreasing tensile stress is achieved across the cross section of the rod, which at all points is greater than zero but less than the threshold stress at which a mist zone forms, by simultaneously applying longitudinal tension to the rod and bending it in a tool that laterally moves a section of the fiber while holding sections to either side in friction-type clamps. A convenient hand tool for breaking optical fibers uses pivoting clamps which serve to increase tensile stress as bending is increased. Scoring is done before or after the above-mentioned tool operations.

Abstract: Graded-index fibers, which are the most promising for first-generation optical communication links, are improved for multimode transmission by employing two or more glassy dopants in the core mutually graded with respect to the silica host and to each other to provide simultaneously minimized intermode dispersion at a first-selected wavelength and, in addition, a broader wavelength range of minimized intermode dispersion, or minimized intermode dispersion at a second distinct wavelength pertinent to the multimode transmission, or optimization of another dispersion-related property of said fiber.

Abstract: Substantial reductions in the distortion loss in an optical fiber waveguide due to the influence of random external forces can be realized by encasing the fiber in a properly designed jacket. In accordance with the disclosed invention, the ability of a jacketed optical fiber structure to resist external forces is characterized by a parameter referred to as its retention length R, given by ##EQU1## WHERE H is the flexural rigidity of the jacketed fiber and D.sub.f is the lateral rigidity of the jacketed fiber. It is shown that minimum distortion loss can be achieved by designing the fiber jacket so that the retention length R of the combined fiber-jacket structure exceeds a critical coupling wavelength .LAMBDA..sub.c for the fiber. A variety of illustrative jacket designs are described.

Abstract: A method of breaking a rod of brittle material, such as a glass optical fiber, so as to yield a mirrorlike surface across the entire rod end is described. This is achieved by establishing a decreasing tensile stress across the cross section of the rod which, at all points, is greater than zero but less than the threshold stress at which a mist zone forms. This is conveniently achieved by simultaneously applying longitudinal tension to the rod and bending it. A convenient hand tool for breaking optical fibers is also described.