AN141

The Photonics Pioneer

Bidirectional Multifiber Insertion and Return Loss Testing
Using OP940 and OP721
Software and cable configurations that will yield high quality return loss measurements

Overview
With 100G Ethernet and beyond quickly becoming the standard for the fiber optics communication industry, many cable manufacturers
want to be able to test multifiber cables with relative speed and ease. Using an OP940 and OP721 with OPL-MAX, an operator cantest bidirectional insertion loss and return loss on high-fiber-count cables.
The test setup should be as follows:

Figure 1: Test setup for measuring IL/RL bidirectionally for multiple channels

The OP940 Insertion Loss and Return Loss Test System connects to the input and output of the OP721 Bidirectional Optical Switch.
HPR cables are then connected to the switch channels of the OP721 (up to 24 channels in each direction) which then connect tofanouts with the DUT residing between these fanouts; an MPO ribbon fiber DUT is used in this illustration.
*DUT: Device Under Test**HPR: High Performance Reference Cable

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

OptoTest Corp.

08/ 01/18+81-568-79-3536

Doc: AN-141 Rev.A

www.santec.com
The Photonics Pioneer

SANTEC USA CORPORATION
1.8 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

Bidirectional MultiFiber IL and RL Testing
Using OP940 and OP721

AN141

The Photonics Pioneer

OPL-MAX Test Sequence
The test configuration in OPL-Max is the same for this equipment setup as it is for the setup outlined in Application Note 113.
For a 12-fiber MPO cable, the sequence file should be as follows:

Figure 2: Sequence file for 12-fiber MPO cableAs with all sequence files, Column D will specify which fiber in the cable will be tested, Columns E and F will specify wavelength(s)and Columns G and H specify the power meter and channel used for testing. In the case of the bidirectional test with an OP940 andOP721, these Columns G and H, as above, should read “OPMRL1” and “1-12”, respectively.
Since the distance from the front panel to the RL reference is not guaranteed to be the same for both directions, it is advised thatColumn N appears as shown above. The “1” in the first channel in the forward direction (coming from the A-B port) and a “-1” for theremaining channels in that direction will allow the RL Reference to be copied from the first channel to all forward direction channels.
Likewise, a “2” and “-2” for the reverse direction (coming from the B-A port) channels will have the same effect, but allow for thesechannels to be referenced separately from the forward channels.
Columns S,T, and U are the only fundamental departure from a standard sequence file since it is not necessary to include on
unidirectional sequence files. For all forward direction channels, columns should read “1” and for all reverse direction channels,
this column should read “2”.

2

SANTEC CORPORATION
OptoTest
Corp.

5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,
Camarillo,
CA Japan
93012
Doc: AN-141 Rev.A 08/ 01/18+81-568-79-3536

www.santec.com
The Photonics Pioneer

SANTEC USA CORPORATION
1.8 05.987.170 0USA Toll Free
+1-800-726-8321
sales@ optotest.com
engineering @ optotest.com
SANTEC EUROPE LIMITED
Tel. +44-20-3176-1550

Bidirectional MultiFiber IL and RL Testing
Using OP940 and OP721

AN141

The Photonics Pioneer

Referencing Instructions
Bidirectional Insertion Loss Reference
To properly reference insertion loss
bidirectionally, connect the simplex
cables from the source and OPM portson the OP940 to the corresponding
ports on the OP721, labeled S and O
respectively. Do not use an external
power meter for reference. Connect
the reference fanout from the lefthand side to the reference fanout
on the right-hand side via a mating
adapter and perform an insertion
loss reference in the software. Thiswill perform two separate reference
cycles—one for the left-to-right (A-B)
direction and one for the right to left(B-A) direction.

Figure 3: Test setup for measuring bidirectional Insertion Loss

Bidirectional Return Loss Reference
To reference return loss for abidirectional test system, connect thesystem as above leaving end faces
open between the two HPR cables
to create the Fresnal reflection (ifeither fanout is terminated in an APC
connector, an APC-to-PC stub willneed to be utilized to produce anadequate reference reflection). Oncethe reflection is established, perform
a return loss reference cycle in thesoftware. During the reference cycle,
the unit will reference both in the A-B
direction and the B-A direction andretain these distances separately for
their respective measurement cycles.

Figure 4: Test setup for measuring bidirectional Return Loss

3

SANTEC CORPORATION
OptoTest
Corp.

5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,
Camarillo,
CA Japan
93012
Doc: AN-141 Rev.A 08/ 01/18+81-568-79-3536

www.santec.com
The Photonics Pioneer

SANTEC USA CORPORATION
1.8 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

Bidirectional MultiFiber IL and RL Testing
Using OP940 and OP721

AN141

The Photonics Pioneer

Measurement Instructions
Once the system has been referenced, place the device-under-test into the setup
between the two fanouts (as illustrated on the left) and simply select the Test option.
Following this, the software will test the cables in the forward direction and then thereverse direction.

Figure 5: Test setup after system has been referenced

Test Report

Figure 6: Sample test report

4

SANTEC CORPORATION
OptoTest
Corp.

5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,
Camarillo,
CA Japan
93012
Doc: AN-141 Rev.A 08/ 01/18+81-568-79-3536

www.santec.com
The Photonics Pioneer

SANTEC USA CORPORATION
1.8 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