Virtually all singlemode splices are fusion. Multimode fibers can be harder to fusion splice as the larger core with many layers of glass that produces the graded-index profile are sometimes harder to match up, especially with fibers of different types or manufacturers. A fiber optic cable or optical fiber cable is a medium used for transmitting optical signals from one place to another. It consists of a strand of glass fibers inside an insulated casing. The penalty. Common connector types are named FC, SC and LC for single-mode applications and ST for multimode, but there are also dozens of other types, with special qualities such as duplex connections, particularly small size, built-in shutter for improved laser safety, etc. Termination is the other, more frequent way of linking fibers.