AN-102
Polarity Verification
through Loss Testing on Duplex Cables
Over view
Insertion loss (IL) and polarity testing are just a couple of the steps required in the testing of multi-stranded
fiber optic cables. IL testing quantifies the amount of light lost through the cables and polarity testing ensuresthat the correct input is routed to its proper output. Usually these two steps can’t be done simultaneously andrequire almost twice the time. In the case of duplex cables, the OP815D—coupled with OPL-Pro and a proper
configuration setup—can perform both tests at the same time and effectively shortening the testing process.
The example discussed below shows how to combine the two steps into one.
NE WBackgroundFigure 1: OPL-Pro parameter file without polarity verification
NE W

The typical duplex insertion loss setup is displayed above. Inputting “IL” into both columns within the parameter fileleaves both sources on simultaneously, continuously sending out a signal to the power meters. This may work fine for
IL but does not help much for polarity testing. Incorrect values can be measured and can seem correct because theypass even though the two fibers may be incorrectly routed, so polarity must be verified to ensure correct inputs tooutputs.

Figure 2: OPL-Pro live display for duplex cables

The images above comply with the configuration setup previously shown. To the left the DUT is properly connectedwith straight polarity, while on the right the same DUT is connected in a cross polarity fashion. They both indicate
passing, making it almost impossible to determine if the selected DUT is the right configuration or not.

1SANTEC CORPORATION
5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,
Camarillo,
CA Japan
93012

OptoTest Corp.

Doc:AN-102 Rev. A 5 /16 /13+81-568-79-3536

www.santec.com

SANTEC USA CORPORATION
8 05.987.170 0
USA Toll Free
+1-800-726-8321
sales@ optotest.com
engineering @ optotest.com
SANTEC EUROPE LIMITED
Tel. +44-20-3176-1550

Polarity Verification
through Loss Testing on Duplex Cables

AN-102

Test Setup for Testing Duplex Cables with Straight Polarity
Configuration
Setting up this configuration is very similar to the configuration for polarity testing except for one major
NE Wchange: “IL2” must be moved to the J column and “IL1” to the K column. This tells the software that whenILis being measured, turn on source A and have OPM2 expect a reading. The same is true for source B, but for
OPM1.
NE W

Figure 3: OPL-Pro parameter file setup for straight polarity configuration

Be sure to save this configuration and then select it on OPL-Pro. If a previous setup is selected, the software will ask
the user if they want to re-reference, which they can choose Yes or No.

Referencing
Using a Duplex cable as a reference
cable, connect the source connector
1 and the end faces that correspondto source should connect to 1 andsource 2 to 2 .

Figure 4TestingThis cable configuration shows the straight polarity case. Note that red corresponds to source 1 and blue source 2 .
Its corresponding output is in the same color and defines how it should be to obtain proper measurements.
Connect the LC-LC straight polarity DUT attached between the reference cable and the OPMs. Verify that it is theright polarity when connecting.

Figure 6: Above shows two values: one passing andReference
Cable
Figure 5DUT
LC-LC

one failing. The passing values verify that the DUT
passes for both IL and polarity. The dark values(right) show that the cable is failing whether it’s bybroken cables or incorrect polarity.

LC-LC

2SANTEC CORPORATION
OptoTest Corp.
5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,
Camarillo,
CA Japan
93012
Doc:AN-102 Rev. A 5 /16 /13+81-568-79-3536

www.santec.com

SANTEC USA CORPORATION
8 05.987.170 0USA Toll Free
+1-800-726-8321
sales@ optotest.com
engineering @ optotest.com
SANTEC EUROPE LIMITED
Tel. +44-20-3176-1550

Polarity Verification
through Loss Testing on Duplex Cables

AN-102

Test Setup for Testing Duplex Cables with Crossed Polarity
Configuration
Setting up this configuration is very similar to the configuration for polarity testing except for one major N E Wchange: “IL2” must be moved to the J column and “IL1” to the K column. This tells the software that when IL
is being measured, turn on source A and have OPM2 expect a reading. The same is true for source B, but forOPM1.
NE W

Figure 7: enter text here OPL-Pro parameter file setup for crossed polarity configuration

Referencing
To test with crossed cables, the reference
should be crossed then returned to normal
polarity so that the OPMs have the correctreference during DUT tests. Connect source
1 to OPM 2 and source 2 to OPM 1 andreference. When the user is ready to attach
the DUT, be sure to flip the reference cables
so that when source 1 sends a signal to theDUT, its crossed configuration sends it toOPM2 and not OPM1.
Figure 8TestingThe cable configuration shown is the crosspolarity case. The setup is similar to that of thestraight polarity DUT except one needs to verify
that the DUT is crossed and that the reference
cables are straight. Therefore when the software
takes measurements, the signal from source 1
will be routed to OPM 2 and vice versa.

Figure 93SANTEC CORPORATION
5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,Camarillo,
CA Japan
93012

Just as before with straight polarity, it shouldbe very evident which output gives passing
measurements and which fail.

OptoTest Corp.

Doc:AN-102 Rev. A 5 /16 /13+81-568-79-3536

www.santec.com

SANTEC USA CORPORATION
8 05.987.170 0
USA Toll Free
+1-800-726-8321
sales@ optotest.com
engineering @ optotest.com
SANTEC EUROPE LIMITED
Tel. +44-20-3176-1550