A Splitter/Combiner cable module connects between dual-fiber and single-fiber optical signals, potentially doubling the data capacity of the installed fiber plant.
Separate Tx and Rx signals from a dual-fiber optical device using the same wavelength over two fibers can be combined through the Splitter/Combiner onto a single bi-directional strand of fiber for the long and expensive run to the remote site. Another Splitter/Combiner at the remote site splits and combines the signals for the dual-fiber device at that location.
Splitter/Combiners are fully passive, and they operate at a specific wavelength. They are transparent to networks and protocols.