Fiber splitter box is usually used with 2mm or 3mm outer diameter cable, while the other is normally used in combination with 0. Unlike active devices (which require power), splitters operate without electricity, relying solely on the physics of. Fiber optic splitter, also referred to as optical splitter, fiber splitter or beam splitter, is an integrated waveguide optical power distribution device that can split an incident light beam into two or more light beams, and vice versa, containing multiple input and output ends. Rarely, there can be two inputs to provide potential redundancy of route.