Measuring Insertion Loss and Return Loss on Ribbon Fiber Fanouts, like the MTP® to LC cable shown in figure 1 below, can be a streamlined process when using the right equipment and automation software.
For the methods described in this Application Note, only a multichannel IL/RL Tester (OP940) fitted with large area detector (RIN) or integrating sphere (OP-SPHR) is needed. This setup can greatly reduce testing time and inaccuracies caused by additional reference cables and multiple detectors. For even further efficiency in testing, using OPL-MAX software will automate and store all test results.
For measuring IL and RL on an MTP to MTP ribbon cable, please see Application Note AN-104.
Launching OPL-MAX Software
Prior to launching the software, ensure that the remote head detector or integrating sphere is connected and that the OP940 is turned on. Upon starting the OPL-MAX software, the .ini File Check screen will pop up. From the Selected Setup drop-down menu, select the appropriate setup file. It will automatically populate the rest of the fields with the saved sequences and descriptions. Once the proper setup is selected, click Launch Application.
Testing the MPO Side
This method of testing MTP fanout cables requires an MTP-to-FC/APC fanout cable connected to the source and two large area detector adapters: In this example, MTP and LC.
This section of the Application Note will make use of the following sequence file to perform the references and measurements described.
For these breakout cables, you will notice a <Pause> in each step of the sequence allowing the operator time to switch fibers on the fanout side of the DUT.
This can also be edited and viewed in Excel through Edit > Edit Sequence in Excel on the toolbar.
OPMRL1 refers to the large area detector associated with the OP940. This sequence shows that insertion loss referencing and testing will be performed on the same large area detector. After getting the sequence properly configured, save the file and go back into OPL-MAX. Click the Load New Sequence button and select the newly created sequence.
In the Setup menu, select the Data File tab to select the proper data file for the test report and go to the Measure tab to configure the test report headers.
Insertion Loss Reference
Connect the FC/APC connectors of your High Performance Reference Cable (HPR) to the outputs of the OP940 and the MTP connector into the large area detector. When the reference setup is configured, press the Ref button and the software will perform the reference cycle.
Return Loss Reference
When insertion loss referencing is completed, the user will be prompted to take a return loss reference. Upon clicking Yes (1) a popup screen will be shown which will guide the operator through return loss referencing (2).
Note that only the first channel is going to be referenced. The rest of the channels will copy this reference, saving valuable time when all channels are the same length. If desired, the software has the capability to reference each of the channels individually.
Measuring the DUT
After referencing, connect the MTP fanout cable under test as pictured below. The MTP connector of the DUT should connect to the MTP connector of the reference cable and the fanout side of the cable should connect to the large area detector via the appropriate adapter.
Note: Ensure the gender of the MTP DUT and HPR are compatible.
Pressing Test in OPL-MAX will begin the measurement process and the system will step from channel 1 to channel 12, measuring the insertion loss and return loss of the MTP connector of the DUT. The pauses in the sequence will allow the
operator to switch between the channels of the fanout side of the DUT.
Measuring the Simplex or Fanout Side
In order to test the simplex side of an MTP fanout cable, a new set of reference cables will be needed. This setup requires one simplex HPR cable. As before, the large area detector will be used for both reference and testing.
Insertion Loss Reference
Connect the reference side of the reference cable to the large area detector using the appropriate adapter. The pauses in the sequence will allow the user to copy the reference values for each step in the sequence. See Figure 6.
Return Loss Reference
The same procedure outlined in the section for referencing RL on the MTP side should be used for referencing return loss on the fanout side of the cable.
On the large area detector, replace the simplex adapter with the LAAD-MTP. Connect the fanout side of the DUT to the reference cables and connect the MTP side to the large area detector. To begin taking measurements, click Test in the software. Step from channel 1 to channel 12 and measure insertion loss and return loss on the simplex connectors.
Verifying Polarity on MPO fanout Cables
Although this method of testing insertion loss and return loss already rules out crossed fibers with passing results, there are two options to explicitly verify the polarity of an MPO fanout cable; one involves using a visible light source, such as the OP280MT, to visually determine that the fibers map to the correct locations; the other method uses a multichannel OP940 and an OP710 multichannel optical power meter with individual detectors in combination with OPL-MAX’s FiberMAP feature.
Using the OP280MT to Verify Polarity
The OP280MT can be used to easily verify the polarity of an MPO fanout cable. Simply connect the DUT to the OP280MT’s source port and either step through each channel manually or use one of the programmed sequences. Verify that the ferrules on the fanout side light up in the proper order. For more information about the OP280MT, contact OptoTest Sales.
Using the OP710 and OPL-MAX to Verify Polarity
OPL-MAX’s FiberMAP feature allows the user to quickly and easily test for polarity using an OP710 and an OP940. The individual detectors on the OP710 allow the software to discern exactly which channels are active at one time, and will provide a visual output of where each source channel maps to. For more information on using FiberMAP, consult our Application Note AN-109 Verifying Continuity with FiberMAP.