How to measure SFP/SFP+/QSFP with the fiber optic tester CFP2-100-Q

SFP module refers to various types of optical modules available (such as SFP+, QSFP, etc.). For this type of module, how can we determine whether the SFP module is working properly? We can use Fluke fiber optic tester to measure the optical power emitted by SFP and SFP itself.

Here, we take the new Versiv2-based CertiFiber Pro fiber loss certification analyzer CFP2-100-Q as an example (CFP-100-Q is a single-mode and multimode integrated tester, CFP-100-M is a multimode fiber tester, and CFP-100-S is a single-mode fiber tester). First, set the CertiFiber Pro tester CFP2-100-Q to "power meter" mode. Select the TOOLS menu on the main screen, and then select the second option. If a CertiFiber Pro module is connected, the option is POWER METER. After selecting this option, you will directly enter the power meter function. The power meter function will automatically start and run without pressing the TEST key.

We need to apply a few simple configurations. Note the lower half of the power meter. The upper half is for transmit and is not needed when testing SFPs. All we need to pay attention to is the absolute power output. I prefer to read the dBm data because it reflects the technical specifications of many SFP modules.

One of the important configurations is the λ (Lambda) or wavelength, located in the lower left corner. What are you testing? If it is multimode - select 850; if it is single mode - select 1310. Press the λ (Lambda) key and select the correct wavelength from the pop-up menu (see the figure below).

Check with the SFP manufacturer for acceptable power levels. Note that if you get a positive number, you will need to add attenuators to your system.

How do I check if an SFP port is clean? There is actually no way to do a particularly effective inspection of an SFP module. Inspection microscopes and related standards such as IEC 61300-3-35 are designed for the connector, not the output port of the SFP. The input port of the SFP should be some type of non-contact large-area input port. The fiber does not actually touch the port directly, so it should be kept fairly clean. Even if there is dust or other debris on the port, it is difficult to see with a microscope.

What if we use QSFP to send 40G through MPO connectors? How to test it? There are two simple options. One is to use a fan-out cable to connect the MPO port to multiple branches of LC connectors. Then plug it into the CertiFiber Pro.

Another option is to plug the MPO cable directly into the MultiFiber Pro . Set it to "Power" mode and you will get the power level of each fiber. This is an example with only one optical receive channel. Click here to learn more about the MultiFiber Pro MPO fiber tester.

Note that if you are working at 40G, you are most likely only using 4 fibers, so don't be surprised if you only see power levels on the first or last 4 fibers on your power meter.