AN113

The Photonics Pioneer

Bidirectional MultiFiber Insertion and Return Loss
Testing Using OP725-OP940 and Two OP720s
Software and cable configurations that will yield high quality return loss measurements

Over view
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 OP725-OP940 and two 1xN OP720 switches withOPL-MAX, an operator can test bidirectional insertion loss and return loss on high-fiber-count cables.
The test setup should be as follows:-0.65

A B
B A

SourceHelp1310nm/1550nm
1490nm/1625nm

13101310

1mm InGaAs

OP940-FTTX

S1O2

OP725-SM-2x2

Input

MTPPULL

MTPPULL

TO REMOVETO REMOVE

OP720

HPR** Cable
Input

OP720

DUT*
HPR** CableE
MTP

TO REMOV

VE

PULL

MTP

PULL

TO REMO

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

The OP725-OP940, Bidirectional Insertion Loss and Return Loss Test System, connects to the inputs of each OP720. HPR cables arethen connected to the output of the OP720 (up to 144 channels) which then connect to fanouts with the DUT residing between thesefanouts; an MPO ribbon fiber DUT is used in this illustration.
*DUT: Device Under Test**HPR: High Performance Reference Cable

1

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

OptoTest Corp.

Rev.B 10 / 22 /15+81-568-79-3536

Doc: AN-113

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 OP725-OP940 and Two OP720s

AN113

The Photonics Pioneer

OPL-MAX Test Sequence
Configuring OPL-Max to run correctly with this configuration is similar to configuring a multi-channel OP725-OP940. 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
OP725-OP940, 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”.

2SANTEC CORPORATION
OptoTest
Corp.

5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,
Camarillo,
CA Japan
93012
Doc: AN-113 Rev.B 10 / 22 /15+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 OP725-OP940 and Two OP720s

AN113

The Photonics Pioneer

Referencing Instructions

Bidirectional Insertion Loss Reference
To properly reference insertion loss
bidirectionally, connect the launchleads from the A-B/B-A source
connectors to the input ports of thetwo switches. Do not use the external
power meter port for reference.
Connect the reference fanout from theA-B switch to the reference fanout on
the B-A switch via a mating adapter andperform an insertion loss reference inthe software. This will perform two
separate reference cycles—one for
the A-B direction and one for the B-Adirection.

-0.65

A B
B ASourceHelp1310nm/1550nm
1490nm/1625nm

1310

1310

1mm InGaAsOP940-FTTX

S1O

2

OP725-SM-2x2

Launch Leads

Input

OP720

HPR Cable

Input

TO REMOVE

OP720

MTPPULLPULMTPTO REMO

LVE

MAAD-MT(MTP Bulkhead)

HPR Cable

Figure 3: Test setup for measuring bidirectional insertion loss

Bidirectional Return Loss Reference
-0.65

A B
B ASourceHelp1310nm/1550nm
1490nm/1625nm

13101310

1mm InGaAs

OP940-FTTX

S1O2

OP725-SM-2x2

Input

OP720

HPR Cable

MTP

PULL

TO REMOVE

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.

Input

OP720

5823 Ohkusa-Nenjozaka, Komaki,
4750 Calle Quetzal
Aichi 485-0802,
Camarillo,CA Japan
93012
Doc: AN-113 Rev.B 10 / 22 /15+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

MTP

3

SANTEC CORPORATION
OptoTest
Corp.

PULL

Figure 4: Test setup for measuring bidirectional return loss

TO REMOVE

HPR Cable

Bidirectional MultiFiber IL and RL Testing
Using OP725-OP940 and Two OP720s

AN113

The Photonics Pioneer

Measurement Instructions
-0.65

A B
B ASourceHelp1310nm/1550nm
1490nm/1625nm

1310

1310

1mm InGaAs

OP940-FTTX

S1O

2Once 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.

OP725-SM-2x2

Input

MTP

PULL

MTP

PULL

TO REMOVE

HPR Cable

TO REMOVE

OP720

Input

OP720

DUTMTP

EPULL

MTP

PULL

TO REMOVTO REMOVE

HPR Cable

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-113 Rev.B 10 / 22 /15+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