How to Build A Passive Optical LAN (Local Area Network)

Posted on November 8, 2016

Local area network (LAN) is being widely deployed in the enterprise, university, hospital, army, hotel and places where a group of computers or other devices share the same communication link to a server. Most of the traditional LAN are based on Ethernet copper cable. As more and more devices and cables are adding to the existing copper based LAN, problems come out. Bottlenecks of bandwidth, cabling space, cable infrastructure are limiting the network services. To better organize the local area network and ensure the network performance, passive optical LAN based on optical fibers, also known as POL, is being deployed.

passive optical LAN

Passive Optical LAN VS. Traditional LAN

Traditional LAN can no longer satisfy the increasing need for higher bandwidth. Passive optical LAN making advantages of the optical fibers, can provide not only higher bandwidth, but also a lot of other benefits to the local area network. Compared with the copper Ethernet cable, fiber optic cables are lower in weight, higher in bandwidth, better in security and smaller in diameter. What’s more, the passive optical LAN can effectively decrease the power consumption up to 40%. Installers don’t need to worry about the heavy copper cable and can be more flexible during network design. Less equipment and enclosures are required in passive optical LAN. All in all, passive optical LAN is the best alternative to the traditional copper based LAN.

passive optical LAN

What Do You Need to Build A Passive Optical LAN?

As mentioned, the building of a passive optical local area network requires less equipment. Most of them have low power consumptions compared with the copper based devices. The above picture shows the basic structure of a passive optical LAN illustrating the main components of a passive optical LAN.

Optical Line Terminal (OLT)

The OLT (optical line terminal) deployed in this passive optical LAN deals with both the upstream signals and downstream signals. OLT receives data from service providers and sending the data to ONTs (optical network terminals). It also gets data from the ONTs and sends it to the providers.

Optical Network Terminal (ONT)

As most part of passive optical local area network is based on optical fibers, before connecting computers and other devices to the passive optical LAN, the optical signals should be transferred into electrical signals generally. ONTs and optical network units (ONUs) are being added to provide copper interfaces to connect the computers and other devices. Some of the ONUs can also provide Wi-Fi.


Fiber Optic Splitter

Generally, there will be one or several fiber optic splitters deployed between the OLT and ONTs. These fiber optic splitters are the passive components which can equally distribute the optical signals to the end users without power supply. Passive optical splitter is a key component in passive optical LAN. The fiber optic splitters are available in various split ratios, fiber type and package form factors. The most commonly used are PLC splitters.

PLC splitter

Connectivity Products

Except for the above mentioned devices, connectivity components are also needed like fiber patch cable, copper patch cable, fiber enclosures, connectors, fiber wall plate, pathway support materials and other cable management components. The whole passive optical LAN is connected by these connectivity and cable management products. These accessories are small but necessary for a high performance passive optical LAN.

fiber wall plate

Case Study of Passive Optical LAN in An Office Building

To show the details of how to build a passive optical local area network, here takes the example of passive optical LAN deployment in an office building. The passive optical LAN cabling solution in an office building is shown in the following picture.

passive optical LAN

The server room is deployed in the first floor where fiber cables from service providers are connected to and fiber enclosures are deployed for better cable management. There is also a fiber enclosure in every floor to manage the fiber cable. Fiber optic splitters are deployed in proper places to distribution optical signals to every ONT/ONU. In this case, all the fiber cables go to the end users from the ceiling or behind the wall, thus, fiber wall plate should better be installed near the ONT/ONU. A length of fiber patch cable (usually simplex fiber patch cable) is used to connect fiber optic port on the faceplate to the ONT/ONU. Then, copper Ethernet patch cables are used to connect computer and other devices to the ONT/ONU. Then, a passive optical local area network is installed.


The deployment of passive optical LAN is simple and has lower requirements for both space and power. Customers can enjoy higher bandwidth with less money. As passive optical LAN can serve end devices from one to several hundred or more, the design of passive optical LAN and selection of related products should depend on the numbers of the devices. It would be better to leave enough fiber optic cables and ports for future use. The above mentioned components can all be found in FS.COM. Kindly contact for more details about passive optical local area network, if you are interested.

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