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White Paper | opticalCON MTP®
Polarity ofMultichannel FiberConnectors

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Content1SCOPE ............................................................................................................................................ 32
MULTI-FIBER CONNECTOR ............................................................................................................ 3
2.1 MPO connector................................................................................................................................ 3
2.2 MTP® Connector ............................................................................................................................. 3
3
TRANSCEIVER ................................................................................................................................ 4
3.1 SFP Transceivers................................................................................................................................ 4
3.2 QSFP Transceiver .............................................................................................................................. 44
4.1
4.2
4.3
4.4

POLARITY ...................................................................................................................................... 4
MPO / MTP® – Adapter keying .. ....................................................................................................... 5
Wiring Method A ............................................................................................................................ 5
Wiring Method B ........................................................................................................................... 6
Wiring Method C ........................................................................................................................... 6

5
5.1
5.2
5.3

NEUTRIK’S WIRING METHOD ....................................................................................................... 6
opticalCON ADVANCED & LITE MTP® wiring with SFP (LC) transceivers ........................................... 7
opticalCON ADVANCED & LITE MTP® 12 wiring with QSFP Transceiver ............................................ 7Conclusion ...................................................................................................................................... 7

White Paper – opticalCON MTP®
Title: NWP04© NEUTRIK AG. All rights reserved.
This white paper is a publication of NEUTRIK AG.
This white paper represents the technical status at the time of printing. The product information,specifications, and all technical data contained within this white paper are not contractually binding.
NEUTRIK AG reserves the right to make changes at any time to the technology and/or
configuration without announcement. NEUTRIK AG is not to be held liable for statements anddeclarations given in this white paper.
NEUTRIK AG explicitly exonerates itself from all liability for mistakes in this white paper.

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31		 SCOPE

As demand grows for fiber optics, multi fiber
push-on (MPO) and MTP® connectors along withrelated quad small form factor pluggable (QSFP)transceivers have become more important in theprofessional broadcast market.

As opposed to common 1.25 mm and 2.5 mm
ferrules, the MT-ferrule is usually terminated witha fiber band of, for instance, 12x 250µm fibers
in a row called “ribbon fiber” (figure 2) which
improves the efficiency of the termination procedure.

2.1 MPO connector
To avoid polarity failures due to intricate multifiber installations, a standardized wiring structureis essential.
This paper explains the primary differences between generic MPO and MTP® connectors. The
paper also shows and discusses standardized
wiring methods. Further sections explain a suitable wiring suggestion for Neutrik´s rugged multifiber connector system – opticalCON ADVANCED& LITE MTP®.

The MPO is an MT-ferrule based multi-fiberconnector defined by the International Electro
technical Commission (IEC 61754-7) andTelecommunications Industry Association &Electronic Industries Alliance (TIA / EIA 604-5). A
male / female ferrule system ensures appropriate
fiber alignment and low return loss values.
Advantages:• Low insertion loss
• Small form factor• High fiber density

2		 MULTI-FIBER CONNECTOR
2.2 MTP® Connector
Resulting on high fiber density the ferrule design
steps away from conventional cylindrical dimensions as used on generic LC, ST, SC, etc. connectors,
instead using cubical mechanical transfer (MT)ferrules (figure 1) made of plastic materials*. The
fibers are aligned in a V-groove and positioned ina row.

The registered trademark MTP® is an improved
fiber optic connector from the company US Conec
based on a generic MPO design.
MTP® connectors are fully intermateable with conventional MPO connectors due to similar dimensions from the MT-ferrule.
Advantages of the MTP® connector:• Re-polish of MTP® ferrules possible• High mating cycles possible due to tighttolerance on guide pins and MT-ferruleFigure 1

Figure 2*…exact material composite depends on ferrule manufacturer

White Paper – opticalCON MTP ®

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3.2 QSFP Transceiver

3		 TRANSCEIVER

Common transceiver modules contain a transmitting port (TX) and a receiving port (RX). On thetransmission side, the electric signal is converted
to an optical signal and transmitted via a lightsource such as a vertical-cavity surface-emitting
laser (VCSEL) or a light-emitting diode (LED).
The receiving side uses photo detectors to receive
the optical signal before converting it back to anelectrical signal for further processing.

QSFP transceivers contain a multi-fiber interface
to connect MPO or MTP® cables directly, thereby
eliminating breakout cables. This enhances theconnection and reduces the risk of polarity-basedfailures. Using QSFP modules, it is possible to transmit more than 40 Gb/s over a single 12-channel
MPO / MTP® cable (figure 6), in a send / return setup.

Figure 6

Figure 34		 POLARITY

3.1 SFP Transceivers

In general it should be guaranteed that thetransmitter (TX) is always connected to a receiver(RX). In a bi-directional fiber setup including atransceiver (TX / RX) on both sides of the cable, adefined wiring setup is essential to ensure that asignal from the transmitter reaches the appropriate receiver port on the other end (figure 7). TheTIA / EIA 568-D.0 standard defines three different
wiring methods in order to avoid polarity failuresand guarantee correct fiber cabling.

Small form factor pluggable (SFP) transceivers(figure 4) are lightweight and hot pluggable
modules which can be plugged in to an appropriate SFP-cage (figure 5). The cage is typically presoldered on a printed circuit board (PCB).

Figure 4

Figure 5

To maintain the polarity different methods areavailable:• Adapter keying (section 4.1)
• “polarity flip” on the patch cable(section 4.2-4.4)• “polarity flip” on the breakout cables		Figure 7settingstandards

54.1 MPO / MTP® – Adapter keying

4.2 Wiring Method A

Multi-fiber connectors contain “keys” which
maintain defined fiber polarity when the connectors are mated together. MPO / MTP® adapters
contain an asymmetrical housing including an
inverted key to achieve the appropriate fiberpolarity.

Wiring Method A uses Type-A “straight through”
MPO / MTP® cables which are mated using Type-AMTP® adapters. All components in the link are
mated key-up to key-down (figure 10). The polarity flip is executed pairwise on the fan-out side ofjust one MPO / MTP® breakout cable at the end.

On Type A adapters (figure 8), the keys areinverted to ensure that the fiber at position 1 isconnected to position 1 in the MPO / MTP® cableconnector at the opposing end (in case of 12 fiberconnectors).
Key upKey down

Figure 8: Type A adapter

Figure 10

On Type B adapters (figure 9) both keys are oriented facing up in order that both MPO / MTP® cableconnectors are mated “key up” wise. The fiber atposition 1 is connected to position 12 in the MPO/ MTP® connector at the opposing end.
Key upFigure 9: Type B adapter

White Paper – opticalCON MTP ®

Advantage:• Easy to implement• Widely used methodsettingstandards

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4.3 Wiring Method B

4.4 Wiring Method C

Wiring Method B uses Type-B “straight through”
MPO / MTP® - cables (figure 11) which are matedusing Type-B MPO / MTP® adapters. All components in the link are mated key-down to key-down.
As a result, transmitting port TX1 on fiber position
1 at one end is connected to receive port RX1 onfiber position 12 at the other end.

Method C uses Type-C “pair-ﬂipped” MPO /MTP®-cables (figure 12) which are mated using
Type-A MPO / MTP® adapters. All components
in the link are mated key-up to key-down. In
this connectivity method, the polarity flip is done
inside the MPO / MTP®-cable.

Figure 12
Figure 11Disadvantage• Not widely implemented• Not suitable for single-mode APC applications

5		 NEUTRIK’S WIRING METHOD

The opticalCON MTP® chassis connector
NO12FDW-A represents a Type A adapter (section4.1) using a key-up to key-down configuration(figure 13).
The opticalCON ADVANCED MTP® cable contains
a “straight through” configuration to ensure
fiber wiring in accordance with wiring method A,
according section 4.2.

Figure 13

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5.1 opticalCON ADVANCED & LITE MTP®
wiring with SFP (LC) transceivers

5.2 opticalCON ADVANCED & LITE MTP®
wiring with QSFP Transceiver

When connecting pairs of opticalCON chassis connectors with SFP transceivers modules, both chassis connectors are used as Type A adapter with key
up to key-down configurations. The opticalCON
MTP® cable contains a “straight through” configuration. The polarity flip is executed pairwise on
one MPO / MTP breakout cable (figure 14).

By using QSFP transceivers (figure 15), the requirement for multiple SFP modules is eliminated. MPO/ MTP® patch cables replace conventional breakout cables, streamlining cabling and connectorrequirements. The only consideration required isthe fiber polarity of the MPO / MTP® patch cable
just one patch cable per link needs to be of Type B.

Figure 14

Figure 15

5.3 Conclusion
On multi-fiber installations, it is in the interest ofboth the installer and end-user to choose a wiring
method that adheres to the TIA / EIA 568-C.0 standard in order to avoid failures related to incorrect
fiber polarity and minimize costly troubleshooting.
Further, it is highly favorable not combine thewiring methods within a single installation as theTIA / EIA 568-D.0 standards states: “it is recommended that a method be selected in advanceand maintained consistently throughout an installation.” Due to its enhanced cable manageability
as well as its compatibility with angled polishedconnectors, Neutrik has chosen wiring Method A
including “straight through” cable wiring alongwith type A adapters for opticalCON MTP®.
White Paper – opticalCON MTP ®

Germany / Netherlands / Denmark / Austria
Neutrik Vertriebs GmbH, Felix-Wankel-Strasse 1, 85221 Dachau, Germany
T +49 8131 28 08 90, info@neutrik.deGreat Britain
Neutrik (UK) Ltd., Westridge Business Park, Cothey Way
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Associated companies
Contrik AG
Steinackerstrasse 35, 8902 Urdorf, Switzerland
T +41 44 736 50 10, contrik@contrik.ch
H. Adam GmbH
Felix-Wankel-Straße 1, 85221 Dachau, Germany
T +49 08131 28 08-0, info@adam-gmbh.de

www.neutrik.com

opticalCON MTP® White Paper 2016/01 V1 – NWP04 – Data subject to change without prior notice. © 2016 NEUTRIK®. NEUTRIK®, opticalCON MTP® are registered trademarks of NEUTRIK AG. ALL RIGHTS RESERVED.

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