The measured transmission capacity for each core ranged from ~0. To date, Sumitomo Electric has developed a randomly coupled 4-core optical fiber, a randomly coupled 7-core optical fiber, and a randomly coupled 19-core optical fiber with a standard cladding diameter suitable for long-distance large-capacity transmission. This is a major step to realize future long-distance. Research on new types of optical fibers and optical transmission systems that exceed the limits of conventional optical fiber transmission is being actively pursued around the world. Have a network installation project? How Does Fiber-Optic Cable Bandwidth Work? Fiber-optic cable bandwidth transmits. With a capacity-distance product of 1.