High Dimensional Free-space Building-to-Building Link for Last-Mile Communications

I propose a new approach to supplying technologies for the last-mile global communication networks.

High-speed data links are central to an ever-more integrated digital economy where, every day, more and more data is shared on our already over-stretched communications networks. A key challenge is the development of new high-bandwidth, secure communication networks, particularly through the internet. The online multimedia services we use on a daily basis are huge users of network bandwidth. With the number of multimedia users in the UK increasing on a monthly basis, the result is a huge drain on the available network bandwidth. Even in standard definition, watching our favourite TV show uses around 1GB of data per hour (and 3GB per hour for high definition). Beyond multimedia, as cloud-based storage and computing becoming the norm establishing high-bandwidth communication networks will be vital. Core backbone communication networks are regularly upgraded to deal with these demands, however the last-mile network, which takes our Internet services to homes and offices, is difficult and expensive to upgrade. This difficulty arises from the distributed nature of this portion of the network and solutions for cost effective, and sustainable, upgrades are required to be commercially deployed over the next 5-10 years.

This project the aims to develop solutions to implementation of high-speed free-space last-mile networks. Using light beams carrying Orbital Angular Momentum, a single point-to-point link will increase the number of data carrying channels. Using orbital angular momentum in this way is an example of spatial multiplexing. These multiplexing techniques have the potential to offer multiplicative increases in data rates whilst simultaneously increasing the security of the link. A key deliverable will be the development of a last-mile building to building link within our new campus, for the development and testing of prototype novel multiplexing and de-multiplexing technology. Working with Industrial partners Intel and Corning, solutions will be developed in line with their market requirement, allowing near-term commercial uptake.

These industry inspired challenges raise some questions about the fundamental nature of long distance propagation of spatial modes. Hence, along with overcoming the technical hurdles this project aims to investigate the effect of turbulence within the free-space propagation of spatially multiplexed beams. In the early stages of this project, studies into the optical aberrations, and modal cross coupling will be carried out in different environmental settings. This vital data will provide a base to design and develop passive, and active approaches to overcoming the limitations imposed by atmospheric turbulence. Further to these challenges, techniques to allow integration into current installed fibre networks will be developed. The proof-of-principle link will allow real life user testing, where standard internet services will be demonstrated over the link, aiming to providing a commercially viable last-mile link design as a key deliverable of the project.

In the short term (1-5 years), this research will have impact by developing a understanding of the physical challenges, along with the development of commercially viable solutions, through demonstration of a proof-of-principle of a high-dimensional free-space last-mile link. The link characteristic study in it's self will provide a useful set of data for the community on the effects atmospheric turbulence place on different form of optical spatial modes. Beyond this physical study, new bespoke optical tools will be developed that will have use beyond their implementation within communications, with various possible applications in optical metrology. The development of this proof-of-principle link will provide a potentially commercially viable solution for building-to-building last mile communications systems. Working with Intel and Corning, commercialization possibilities will be assessed throughout the development the system, where their input will shape the system to suit the current and future market requirements.

In the medium term (5-10 years), communications providers will have begun their 5G deployment to their installed customer base. This extensive technological role out will have begun to place strain on the large distributed communications networks, where customers are costuming ever more data; spurred on by the increase networks speeds. The desire for fast, secure reliable last-mile networks will become an imminent concern, as end users bandwidth usage will place increased strain on the last-mile portion of the network. The technical outcome from this project will have provided technology that could be installed as part of the 5G role for use with in last-mile network upgrades. High dimensional spatial multiplexed links will be vital in the medium term to relieve the stress on point-to-point communications links.

In the long term (10-50 years), it is likely the network architecture will have drastically changed from that of the current installed systems. Traditional backbone, to local nodes, which are connected to the distributed last-mile network will potentially no-longer be the most efficient network architecture. With the internet of things changing the landscape of what devices are network enabled and integrated, our network will also have taken on a different more natural form. Smart, Adaptive networks will be the norm, where physical network will themself adapt to network usage and failure. Such a rich digital ecosystem will limit the appropriateness of tethered devices, and limit the feasibility of optical fiber for last-mile networking solutions. The last-mile, distributed network could become the main workhorse of the movement of data traffic, managing the best way to route data the network removing the requirement for incredibility high-backbone network links. Developments made now in the technology requirements for high speed spatially multiplexed free-space links will prove formative in the technology utilized in these possible future network architectures.