A passive splitter does exactly what its name implies: it splits a signal without using any external power. Whether you're dealing with fiber optic networks, HDMI video systems, or RF distribution, splitters help ensure that your signal reaches multiple endpoints efficiently. Typically, but not always, there is one input in and multiple outputs. Some examples: A coupler can be used as a splitter to couple out some portion of the light circulating in the resonator of fiber laser, for example. Directional 2 × 2 couplers (see Figure 1) are usually used for.