Splitters – What do they do?
Passive Optical Network (PON) splitters play an important role in Fibre to the Home (FTTH) networks by allowing a single PON network interface to be shared among many subscribers. Splitters contain no electronics and use no power. They are the network elements that put the passive in Passive Optical Network and are available in a variety of split ratios, including 1:8, 1:16, and 1:32.
PLC Splitters are installed in each optical network between the PON Optical Line Terminal (OLT) and the Optical Network Terminals (ONTs) that the OLT serves. Networks implementing BPON, GPON, EPON, 10G EPON, and 10G GPON technologies all use these simple optical splitters. In place of an optical splitter, a WDM PON network will use an Arrayed WaveGuide (AWG).
A PON network may be designed with a single optical splitter, or it can have two or more splitters cascaded together. Since each optical connection adds attenuation, a single splitter is superior to multiple cascaded splitters. One net additional coupling (and source of attenuation) is introduced in connecting two splitters together.
A single splitter is shown in the GPON network diagram below. Note that the splitter can be deployed in the Central Office(CO) alongside the OLT, or it may be deployed in an OutSide Plant (OSP) cabinet closer to the subscribers. A splitter can also be deployed in the basement of a building for a Multiple Dwelling Unit (MDU) installation.
Splitter in GPON Network
An interesting fact is that attenuation of light through an optical splitter is symmetrical. It is identical in both directions. Whether a splitter is combining light in the upstream direction or dividing light in the downstream direction, it still introduces the same attenuation to an optical input signal (a little more than 3 dB for each 1:2 split).