Whitepaper
Multfiber connectors as key components in the passive fiber optic infrastructure
EBO MPE: Why EBO next generation technology is a genuine alternative to MTP®/MPO connectors!
The new expanded beam technique permits singlemode and multimode lensed ferrules
Global data volumes are growing at a furious pace. Driven by increasing levels of digitalization, the requirements placed on data centers are constantly growing. Huge quantities of data have to be transferred quickly, securely and reliably. As a result, the requirements placed on data center components such as plug connectors and, in particular, multifiber connectors are also increasing because these have a decisive influence on signal transmission. High-quality fiber-optic connectors ensure outstandingly high data transmission rates and uninterrupted availability. This makes it all the more important to choose, use and maintain fiber-optic connectors correctly.
Multifiber connectors for a high-performance data network
In order to achieve high data rates, many data center operators are already using 400 Gigabit Ethernet networks. Currently established Ethernet versions for singlemode applications achieve the speeds 400GBASE-FR4 and 400GBASE-DR4. The 400G Multimode OM4 application 400GBASE-SR8, which was introduced in 2019, is now being superseded by 400GBASE-SR4. Both of them require APC 8° obliquely cut OM4 MTP®/MPO plug connections.
Due to the growing bandwidth requirements, the demand for optical 800G transceivers is also increasing, fuelled in particular by the growing popularity of hyperscale data centers. The 800GBASE-R standard defines the base layer for 800G networks. The basis for the 800GBASE-R specification is provided by the existing 106.25G lanes, which were defined in 400G Ethernet applications. To achieve greater bandwidths, the number of total lanes in Physical Coding Sublayers (PCS) will be doubled from 4 to 8.
Standardized transmission methods for singlemode solutions include 800G-DR4, 800G-FR4, 800G-DR8 and 800G-PSM8, while 800G-SR8 is available as a multimode application.
The introduction of ever higher transmission standards makes it clear that the use of parallelization technologies will continue to grow in importance. This is underpinned by the fact that the maximum serial “lane speed” with NRZ coding of multimode transceivers is currently 50 Gigabit/s, whereas it is 100 Gigabit/s with PAM4 coding. Consequently, for the transmission of higher speeds, such as 100, 200, 400 or 800 Gigabit Ethernet, it is necessary to make use of “parallel optic transmission”. These multimode parallel optics transceivers require multimode connectors such as MTP®/MPO, MPE, MMC, SN-MT or 4 or 8 SN® as well as MDC duplex connectors packed closely together at their Media Dependent Interfaces (MDI).
Clean connections for reliable data transmission
The performance capabilities of fiber-optic cabling are crucially dependent on the cleanliness of the fiber ends. This is because only clean plug connections achieve the low insertion losses (IL) needed by the transceivers, coupled with the stable, high return losses (RL) that are becoming increasingly necessary. In particular, the constantly growing data rates make the transmission quality more sensitive to contaminated plug connections. Even small particles of dirt or other contaminants such as grease or dust can significantly impair the transmission properties of a fiber-optic connection. Depending on the structure of the fiber-optic connector, special equipment and the corresponding expertise may be needed for cleaning. However, not all fiber-optic connectors exhibit the same sensitivity to dirt. Connectors in which the expansion of the light signal is achieved while avoiding any physical contact with the end surfaces are less sensitive to contamination and therefore have to be cleaned less often, if at all.
MTP®/MPO connectors - Parallel optics and contamination as a risk factor
The MTP®/MPO is a low-loss multifiber connector with a maximum of 72 fibers. The so-called “by 12” configuration, in which up to 6 rows of 12 fibers each are arranged above one another, has been available since the 1990s, and the so-called “by 16” variant, in which up to 2 rows of 16 fibers are arranged above one another, has been available since 2017. The connector system has been internationally standardized as MPO in the IEC 61754 series and is therefore vendor-independent. This is an advantage in terms of procurement because the connector is non-proprietary and can therefore be ordered from a range of sources.
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In the field of parallel optic data transmission, the MTP®/MPO connector has been the standard plug-in system from the very beginning. This connector should be the solution of choice for anyone opting for parallel optics and who also wants to remain flexible in the future for migration to higher data rates. This is because one forward-looking parallelization solution that enables data centers to provide outstanding data transmission speeds takes the form of multimode MTP®/MPO cabling systems. For 400GBASE-SR8, this is the MTP/MPO 16 SEDECIM Multimode APC 8°, whereas for 400GBASE-SR4, it is the MTP/MPO 4+4 OCTO Multimode APC 8°. In the case of 800G Singlemode DR8 and PSM8, the MTP/MPO 16 SEDECIM Singlemode APC 8° or two parallel MTP/MPO 4+4 OCTO Singlemode APC 8° connectors can be used.
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The great drawback of the MTP®/MPO connector lies in its high sensitivity to dirt. The result of this is that unproblematic acceptance measurements cannot be performed without suitable MTP®/MPO tools and the corresponding expertise.
Eliminating contamination as a risk factor - Tools
MTP®/MPO-compatible video microscope
(Source: 3-EDGE GmbH)
MTP®/MPO-compatible measuring equipment
(Source: AMS Technologies AG)
MTP®/MPO Cleaner
Multifiber expanded beam connector systems with EBO technology - a genuine alternative?!
Multifiber expanded beam connector systems are an alternative way to eliminate the basic problem of the contamination of fiber-optic connector systems. Due to its design, the new Expanded Beam Optical technology patented by 3M™ is inherently less sensitive to contamination and will usher in a range of potential data center applications.
What makes the expanded beam concept so suitable for fiber-optic connectors?
What makes the expanded beam concept so suitable for fiber-optic connectors?
As the name suggests, the concept is based on the technique of expanding the light beam. As a result, the proportion of the surface occupied by a particle of dirt in the beam path is much smaller. Performance deterioration due to dirt particles is therefore significantly reduced.
In contrast to earlier expanded beam methods, the 3M™ EBO ferrule uses a new mirror reflection collimation technology to expand the light path and completely overcome the effect of surface particles on insertion loss and return loss performance.
The 3M™ EBO ferrule is vapour-coated with a special AR coating that very efficiently reduces the reflection of light beams. Tiny deviations in the fiber orientation in plug connections (lateral offset) are all but eliminated.
New expanded beam technology permits singlemode and multimode multifiber lensed ferrules
The new ferrule design, which has been patented by 3M™, not only supports multimode applications but also makes it possible to use the expanded beam in singlemode solutions – a unique market capability for multifiber ferrules.
The 3M™ Expanded Beam Optical (EBO) connector system is equipped with a single ferrule able to accommodate 12 singlemode or multimode fibers. However, the system is scalable and can be used to connect up to 144 fibers. EBO ferrules will soon be available with a 16-fiber design. Depending on the type and size of the connector housing, one or more ferrules can be accommodated in a single connector.
The greatest advantages of expanded beam technology
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The innovative, hermaphroditic structure of the expanded beam ferrule system permits easy installation and extremely high numbers of mating cycles with no loss of performance. And without even having to clean the end surfaces.
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The end surfaces of the lenses are not in physical contact, making expanded beam connections extremely insensitive to contamination. The risk of scratches and damage due to dirt particles is therefore eliminated. At the same time, the solution guarantees excellent IL and RL performance for expanded beam connectors.
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Another major advantage of the system lies in the total reflection, which causes the signals to exit the ferrule rotated through 90° before being captured again on the opposite side. This protects users from laser beams that are harmful to the eyes, because the signals do not exit the connector in a straight line.
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Given the rapidly growing numbers of fiber-optic connectors being used in data centers, these advantages greatly enhance operational reliability. The significantly simplified handling and the elimination of the need for time-consuming inspection and cleaning activities also considerably reduce operating costs.
High-bandwidth fiber-optic technology for many fields of application
Possible applications for the EBO connector principle in data centers are:
- Hyperscale data centers
- AI applications
- Trunk cables
- Patch location
- ToR and EoR distribution
- Ribbon applications to PCBs
- Harnesses
Example: Application in a hyperscale data center
From the MTP®/MPO 12 to the EBO MPE 12 connector - What needs to be considered?
The EBO MPE 12 connector consists of an MPO connector housing with an EBO instead of an MT ferrule, plugged together in a conventional MTP®/MPO connection to form a plug connection. The footprints of MTP®/MPO and EBO MPE connectors are therefore identical.
This makes it possible to continue to use panels with MTP®/MPO connections provided that trunks with the associated patchcords and harnesses with EBO MPE 12 connectors are employed.
Procedure
When switching over from MPO to EBO plug connectors, it is possible to re-use the connections 1:1. Conversion is a simple task due to the hermaphroditic design of the expanded beam ferrule systems.
The passive infrastructure that has already been constructed can therefore be replicated in full using EBO MPE connectors and there may be no need to change the connections. Any pre-existing racks/panels or inserts can be taken over 1:1.
Conversion is currently possible for 12-fiber cabling installations.
Summary:
For more than 20 years, the MTP®/MPO connector has been a basic component of fiber-optic infrastructures in most corporate and hyperscale data centers and is widely used (alongside LC-duplex) in structured database cabling right down to the level of the individual transceiver connections.
In the field of parallel optic data transmission, the MTP®/MPO connector is currently the standard plug-in system. This is because most transceivers currently use MTP®/MPO connectors at their MDIs.
Another highly promising multifiber expanded beam connector system is becoming available on the market in the form of the 3M™ Expanded Beam Optical (EBO) next generation of ferrules. These are supported by numerous transceiver manufacturers that have developed a footprint for the EBO MPE (e.g. HG Genuine, China).
It will be exciting to see whether the innovative EBO technology becomes an established solution for data centers. The availability of singlemode multifiber lens ferrules and compliance with essential quality criteria placed on fiber-optic connector systems mean that this technology is in an excellent position to succeed.
In general, it will be necessary to assess the extent to which the very slightly higher signal attenuation values of multifiber expanded beam connector systems fit within the specific attenuation budget. In addition, it will also be necessary to consider other factors such as the length of the cable path and the number of patches.
As the transmission speeds in data centers continue to increase, so, too, will the need for reliable multifiber connectivity. In the future, the EBO ferrule will be available in a 16-fiber variant. There is therefore no longer anything to prevent EBO technology advancing into the field of data center cabling.
About Rosenberger OSI:
Since 1991, Rosenberger Optical Solutions & Infrastructure (Rosenberger OSI) has been an expert in innovative fiber optic cabling infrastructure and service solutions for Data Centers, Local Networks, Telecom and Industrial. The products and services can be found wherever largest amounts of data have to be transferred quickly and securely. In addition to the development and production of a broad portfolio of fiber optic and copper cabling systems, Rosenberger OSI also offers a variety of services such as planning, installation and maintenance of cabling infrastructure. Rosenberger OSI employs about 800 people and has been a part of the globally operating Rosenberger Group since 1998, a worldwide leading provider of high-frequency-, high-voltage-, and fiber-optic-connection solutions headquartered in Germany.