PLC Splitters are usually used in passive optical networks (PONs) to distribute fiber to individual homes or businesses. There is something different between testing an optical splitter and a patch cable although both of them use an optical power meter and light source to test. In this tutorial, we are going to introduce optical splitter loss testing with optical power meter and light source.

Optical splitter (i.e., PLC splitter) is a connection components with multiple inputs and outputs, which can realize the combine, splitting and distribution of optical fiber signals in passive network systems(PONs), and is a crucial component of fiber optic links. Usually, the use of M × N to indicate a splitter has M inputs and N outputs, nowadays the most commonly used in the network is 1 × 2, 1 × 4 and more splitters. So how much of the accentuation?

Here is a table of typical losses for splitters.

Note:

1. Excess loss is the ratio of the optical power launched at the input port of the splitter to the total optical power measured from all output ports. It assures that the total output is never as high as the input.
2. Insertion loss is the ratio of the optical power launched at the given input port of the splitter to the optical power from any single output port. The insertion loss includes the splitting loss and excess loss.

Let’s start with the simplest 1×2 optical splitter as the picture shown below. First, attach a launch reference cable to the optical light source of the proper wavelength (some splitters are wavelength dependent), and then calibrate the output of the launch reference cable with the optical power meter to set the 0dB reference. Attach the light source launch to the splitter and attach a receive launch reference cable to the output and the optical power meter, and then measure the loss.

Similarly, to test the loss to the second port, move the receive launch cable to the other port and read the loss from the meter. For the other direction from all the output ports, we should reverse the direction of the test.

For other 1xN optical splitters, e.g. 1×32 splitter, this test method can also be used. Just set the light source up on the input and use the power meter and reference cable to test each output port in turn. But for upstream, we have to move the light source 32 times and record the results on the meter.

So, how about the 2X2 splitter? In this case, a lot of data are involved sometimes but it needs to be tested. We would need to test from one input port to the two outputs, then from the other input port to each of the two outputs. In the same way, we can test other 2xN splitters.

Tips: What you are measuring is the loss of the splitter due to the split ratio, excess loss from the manufacturing process used to make the splitter, and the input and output connectors. So the loss you measure is the loss you can expect when you plug the splitter into a cable plant. Once installed, the splitter simply becomes one source of loss in the cable plant and is tested as part of that cable plant loss for insertion loss testing.