PETER DYKES CONNECTIVITY
speck of debris will have a detrimental effect on the signal light path. Similarly, using small diameter cores in dense environments makes alignment ever more difficult. US Conec has developed what it calls “free space” connectors in which the fibre cores do not actually touch in the traditional way and which address both of these issues. Hughes says, “We’re looking at a new kind of optical connector technology that’s lens-based. We do an expanded beam connector interface that allows us to hook up lots of fibres quickly, does not need cleaning and does not need a highly skilled technician to install it.” He explained that by placing a lens in front of each fibre end, the diameter of light beam can be expanded by a factor of four, thereby reducing the effective size of a speck of debris in relation to the beam. Hughes says, “Almost all the connectors we use today are physical contact connectors, which literally bring the fibres together, align them precisely and let them touch, kind of like a temporary splice. If there’s a separation between the cores, we get reflections and attenuation and that’s bad news. So, if the connection is designed to operate in free space, by definition we aren’t bringing them together to touch anymore, which makes us tolerant in the Z axis alignment, which is a big help when it comes to any debris that might be in the mechanical structure. So we typically use collimated light that’s not sensitive to Z axis alignment. The result is we get very forgiving connector technology.” READY FOR 5G? No discussion of connectors would be complete without mentioning 5G and IoT, given that without fibre, they could not be implemented. However, while some existing connector formats will be applicable a degree of standardisation will inevitably be required. The main bodies include IEC, TIA and IEEE. There are also MSA groups for QSFF-DD, OSPF, and SFP-DD technologies and there are discussions on new optical interface within OIF and other consortiums as
well, but as Leonard observes, “In terms of standards, most connectors are either ISO or Telcordia, but there are others, and there are working groups in various countries that are working standards up to ISO. The fact is, standards are constantly evolving and manufacturers often release proprietary solutions which eventually get updated to conform with standards.” So, is the connector industry ready for the future? Senko says, “We are ready in terms of Passive Fibre Optic connectivity solutions. 5G infrastructure is all about fibre. There are challenges such as the cost of network infrastructure deployment and physical spaces to deploy these infrastructures. We believe fibre optic components, even though it is a small portion of entire network, can help operators to address these challenges. The majority of connector form factors from FTTH and data centre markets are already being utilised for 5G infrastructure. At the same time, there are new technologies actively being developed to support 5G and IoT rollout.” Chivers adds, “With 5G and the increase of IoT these are placing challenging new technical demands on the connectivity components that enable these networked devices. The main challenges for connectors in IoT are the ever- increasing data-rate demands and diverse component densities of end devices from consumer electronics to smart meters and manufacturing control
cannot forget about the MPO connector. The multi-fibre push-on connector really allows for the maximisation of fibre density in an optical connector. It is recently gaining more momentum, as manufacturing process control and precision moulding technology continue to improve thus offering improved optical performance yet at an economical point.”
DENSIFICATION DRIVES DEVELOPMENT
One company that has been actively developing the MPO connector format is US Conec, which has a new version of the MPO with a row of 16 fibres where historically a row of 12 or 8 channels were used. Mike Hughes, VP of Product Development at US Conec says, “One of the reasons we’ve got so many MPO formats is the transceiver bandwidth needing additional lanes. For example, the SR8 that we’re doing for 400G short-reach applications, we needed eight transmit and receive lanes via one MPO connector, so to achieve that, we went to a 16-wide connector. The other thing that’s driving new formats is density. So, we see that like in the duplex world, whereas for years we would have seen the LC format used, now we’ve taken another swing at reducing duplex connectivity with a new format called the MDC, which takes us down to about a third the size of the LC format.” Indeed, density is a driver for a number of connector-related technologies, not the least of which is cabling. Ribbon and high-density cables do present certain challenges, although as Senko points out, there are good challenges, that have served as a catalyst to some of the innovative connector designs SENKO has developed, because connector, fibre, and cable technologies have to evolve together. It adds, “It’s important to be asking the right questions and we believe that working in synergy with our suppliers and customers, we can always find new, unexplored solutions.” Leonard agrees that the challenges aren’t great, but some do exist. He says, “Micro-cables down to 8 microns require specially-made ferrules, which is a bit problematic, but it’s relatively easy to adapt existing connectors to the smaller sizes. We’ve been using MPO, MPT and MPX. Ribbon cables don’t really present a problem as we’ve already got them covered with existing products. Multicore, high-density cables are more of a challenge however, insofar as it’s difficult to align the cores.” Alignment, along with cleanliness, are also issues going forward, as connector density increases and a lot of applications in the industry are looking for ways to develop optical connectors that behave more like their electrical counterparts which are simply plugged in and forgotten about. Cleanliness is a problem because as fibre cores get ever smaller, even the tiniest
equipment. IoT devices are being designed for considerably higher operating frequencies than are
commonly used today and these will all require higher data rates at higher speeds and new connector designs. In addition, higher board-level component densities that enable advanced IoT devices also significantly limit both the space allotted for connectors and the minimum co-location distances between components, which is a critical design element for reducing the risk of interference”.
Stephen Chivers Residential Project Director, Glide
Mike Hughes VP Product Development, US Conec
Brian Leonard European Product Manager, Fujikura Europe
www.opticalconnectionsnews.com
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ISSUE 22 | Q4 2020
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