Lasers fOr Communications AppLications (LOCAL)

The COVID-19 crisis has placed an unprecedented demand on communication networks. The OECD recommends that "Network operators should anticipate increased demand and prevent congestion by upgrading their interconnection capacity" (http://www.oecd.org/coronavirus/policy-responses/keeping-the-internet-up-and-running-in-times-of-crisis-4017c4c9/)

Datacentres require low latency, ultra-high capacity optical data connections. At present data centres are large scale and interconnected by long-haul fibre-optic connections. Within it a data centre has many short range (100-300m), low cost optical links, driven by low cost vertical cavity surface emitting lasers (VCSELs). The long-haul fibre connections (100's-1000's km) are driven by high cost and high-performance edge emitting lasers (EELs).

Future internet of things (IoT) and 5G cellular roll-out will result in sustained growth in the volume of data storage and the volume of data movement which will require changes in the data centre landscape. Initially, an increase in the size of datacentres, requiring longer link lengths is expected. Additionally, low latency and problems in situating centres in urban areas, we expect distributed datacentres, requiring a step up in link-lengths approaching those of current metro networks. This change in system architecture cannot be supported by the present low cost VCSEL technologies as low powers limit the link length to a few hundred metres. Current EEL technologies can offer the required performance but not at the required cost. Following on from the commoditisation of active optical cables for datacentres is another opportunity in future domestic data cables. 8K TV and high speed USB are fighting the limits of copper connectivity, and a switch to optical cabling is now on the horizon. Cost is the ultimate driver for domestic markets, and our establishment in data centre cabling should put us in an ideal position to pursue this large market in the future.

We have developed a new class of laser that due to its unique design allows performance that is better than that of both existing laser types; EELs and VCSELs. It comes with added wavelength agility (i.e. it can be applied to almost any emission wavelength) and has major cost advantage. The cost advantage from surface emission allows for; on-wafer testing, the packaging of only known good die, and the opportunity of on-wafer burn-in. A symmetric low divergence beam further reduces packaging costs beyond the VCSEL. A key element to the high-speed operation of these devices, allowing high data-rate transmission lies in size scalability to reduce the laser volume.

The technology we have developed will allow the UK to be at the heart of the global photonics market. And with Governments increasingly moving to cloud data storage, access to this supply chain is a key strategic capability.