What are MPO connectors?

MPO—Multi-fiber Push On—is a type of optical connector that has been the primary multiple fiber connector for high-speed telecom and data communications networks. It has been standardized within the IEC 61754-7 and TIA 604-5. This connector and cabling system first supported telecommunications systems especially in the Central and Branch offices. Later it became the primary connectivity used in HPC or high-performance computing labs and enterprise datacenters. It has also been heavily used in cloud datacenters but is now being replaced with the lower cost MXC optical connector and cabling systems because of a much more controlled, benign environment versus the rugged Telcordia testing and validation requirements.

Over the years, the MPO connector family has evolved to support a wider range of applications and system packaging requirements. Now there are several more suppliers investing and developing products with new features and fiber counts. Originally a single row 12-fiber connector, there are now 8 and 16 single row fiber types that can be stacked together to form 24, 36 and 72 fiber connectors using multiple precision ferrules. However, the wider row and stacked ferrules have had insertion loss and reflection issues due to the difficulty of holding alignment tolerances on the outer fibers versus the center fibers. USCONEC, a primary MPO supplier, and others offer a higher precision ferrule and alignment version called MTP Elite versus their MTP standard ferrule and connector housing, but at a higher cost/price level.

Optical loss budgets and the number of connections between active equipment types affect and determine the choice of premium or standard MPO connectors. Telecom infrastructure connectivity systems usually have many more passive optical connections versus newer cloud datacenters that have mostly short intra-rack and intra-row between just two devices. Cloud datacenter racks and row of racks have higher density packaging systems that leave much less space for connector plugs versus telecom wiring cabinets and racks. So there are mini-MPO and micro-MPO connector housings to compete against the smaller MXC housing. At this year’s OFC conference and exhibition, Senko and other suppliers had introduced new smaller MPO products. Combined with more flexible strain-reliefs and newer bend insensitive fiber types for both SMF and MMF these new cable assemblies support more confined routing channels.

Industrial automation systems and datacenters also have benefitted from newer designs using circular and rectangular plastic over-shells. Mining and military use MPOs embedded inside circular metal shells.
There are many newer fiber types like 10G performance MMF OM4 that are using color-coded housings like aqua to more easily discern within the rack.

Besides the MXC system, other competing connector and cabling systems now include using a single multi-core fiber with the LC connector. There are up to 12 or more cores within some newer fiber types. Also competing is the Valdor circular 7 fiber ferrule that fits within the SC or LC connector housing and newer E-Shield 19 and 37 fiber circular ferrules that fit within a SC or LC housing. The circular multi-fiber bundle geometry and multi-core fiber solutions help to provide better insertion loss versus the linear single row 16 fiber MPO system.

MPO connectors will still thrive in many market segments while newer multi-fiber connector will also expand their usages and product features and application options.