Light loss or “loss budget” is the calculation of the total length of the fiber cable and the loss of light traveling that cable, which has a big impact on network performance.
Designing a fiber optic network is a balancing act between the sum of its parts and a few different factors to determine how to power it. I want to go over Garland’s passive fiber TAPs loss specifications and how they factor into determining your budget light loss calculation.
Fiber Cables and Network TAPs
A mated pair is two fibers terminated (both male LC terminated) that are connected together with a fiber optic coupler. For example, a switch and a router connected to one another with two fiber optic cables and a coupler connecting those cables together. That would represent one mated pair in the system (not counting the connections to the router or the switch).
A fiber optic TAP consists of splitters, terminated with LC or MTP® connectors, then connected to a coupler. The technician connects the equipment to the TAP’s couplers to complete the connection. Coming in the network port your light traverses one mated pair then travels through the splitters, traverses one more mated pair to exit the TAP on the other network port or the monitor port.
Determining Light Loss Through Passive Fiber TAPs
Here are three common ways to look at light loss through passive fiber optic TAPs:
1) The loss number through the splitters. Loss numbers for TAPs that have been advertised as a specific number, are just the loss through the splitter. It is important to know that this doesn’t take into account the two mated pairs that exist in the system as mentioned above.
2) The loss number through the splitters plus what we think the loss number will be through one mated pair. Here you have the hypothetical switch and router connected to one another with two fiber optic cables, with a coupler in between them. When you disconnect the coupler (one mated pair) and connect to the TAP you only introduce one additional mated pair and the fiber optic splitter loss.
3) The loss number through the splitters plus what we think the loss number will be through two mated pairs. The switch and router are connected to one another without a coupler in between them (one continuous fiber). Therefore you have introduced two mated pairs and the fiber optic splitter.
This does not guarantee what the loss is through the mated pair. It is the loss that you could obtain assuming you have properly terminated fibers plugged into our TAP. Garland uses Zirconium sleeved LC couplers on both our multi-mode and single-mode LC couplers and MTP® terminated TAPs, which are considered the best on the market.
Garland’s light loss measurement standard is based on Option 2, which includes the TAP plus the introduction of one mated pair. For customers that add two mated pairs we provide you the estimated loss through the mated pair that should be added.
In order to achieve the specified loss numbers, you must make use of quality and clean terminated fibers with our TAP. To determine how much loss you are introducing into the network, take into account if you are introducing one or two mated pairs.
If you are disconnecting two fibers from a coupler and introducing a Garland Network TAP, use our noted specification loss (since you are only adding one mated pair). If there is not a coupler you are removing, then add our loss through the TAP and the mated pair listed at the bottom of the specification table.
If you would like to learn more about loss budget in fiber networks, read our whitepaper Network Connectivity: Basics & Beyond.