Which device is used to distribute optical power among several output ports?

The device that is used to distribute optical power among several output ports is the star coupler. A star coupler operates by allowing light to enter through one or more input ports and evenly distributing that light across multiple output ports. This design is especially useful in fiber optic networks where it facilitates the branching of signals to various locations while maintaining signal quality and strength.

The star coupler typically employs a configuration where all connections are made in a central hub, hence the name "star." This configuration allows for effective load balancing and minimizes the impact of loss in any single output path since the light is divided among all available outputs.

The other options provide different functionalities: an X coupler is typically utilized for specific routing rather than widespread distribution, a tree coupler serves to branch signals in a more hierarchical manner, and a furcation unit is mainly used for the organization of fiber optic cables rather than for power distribution across multiple paths. Each of these devices serves specific purposes in a network but does not perform the broad distribution function of a star coupler.