A passive optical network (PON) is a fiber-optic telecommunications technology for delivering broadband network access to end-customers. Its architecture implements a point-to-multipoint topology in which a single optical fiber serves multiple endpoints by using unpowered (passive) fiber optic splitters to divide the fiber bandwidth among the endpoints. Passive optical networks are often referred to as the last mile between an Internet service provider (ISP) and its customers.

In a PON network, a device called an optical line terminal (OLT) is placed at the head end of the network. A single fiber optic cable runs from the OLT to a nonpowered (passive) optical beam splitter, which multiplies the signal and relays it to many optical network terminals (ONTs). End-user devices such as PCs and telephones are connected to the ONTs.

PON, developed in the mid-1990s, was originally designed to allow Internet Service Providers (ISPs) to deliver broadband triple-play services (data, voice, and video) to residential users.

Its purpose was to reduce the number of fiber runs needed to reach multiple end-user locations and to eliminate the need to provide power to transmission devices between the central office (also called the head end) and the end user. Both of these issues had hindered deployment of FTTP (fiber to the premises) services at the time.

While PON was initially focused on fiber connectivity to the home, other types of network users--such as hotels, hospitals, and high-density residential buildings--are now seeing similar advantages in "last mile" power distribution and fiber efficiency by deploying this technology.

PONs have a number of key advantages; for a start, because they don’t require electrical power for the splitter, they have lower installation and operating costs than AONs. They also use less energy, and less network infrastructure, than AONs, and are highly reliable. Compared to the copper wiring that is being replaced by fiber, using PONs means the fiber is smaller, easier to manage, and more secure than the legacy cabling it replaces.