Atmospheric monitoring for next generation cable free optical communication technologies

Cable-free optical communication systems are vital for building the communication networks of the future. Traditionally wireless connections have been based on radio or microwave systems. However, the capacity of these systems is substantially less than optical systems. Based on detailed analysis on the network requirements from British Telcom, free-space-optical links that incorporate advanced communication technologies such as space-division multiplexing will need to be deployed alongside more traditional fibre distributions meet the capacity requirements of their network in next 5-10 years. Space division multiplexing (SDM) is a communication scheme where laser beams are shaped in the spatial degree of freedom to offer additional communication channels. SDM is widely considered as the next frontier in high capacity communications, where researchers from around the world are highly active in this field.

In this project, we will focus on the central issue of atmospheric turbulence. This turbulence arises from the temperature and pressure variations that occur in the air and result in changes to position, phase and shape of optical modes as they propagate through the atmosphere. This results in errors within communication systems and must be mitigated for error-free data transmission. In this PhD project, the student will develop new experimental systems for determining the effect of atmospheric turbulence on spatially shaped modes. These beams do not propagate in the same way as Gaussian laser modes, therefore we need to develop detailed models of the effects of atmospheric turbulence on spatially shaped light. These studies will then lead to the development of new adaptive optical schemes to fully mitigate the effects of light propagating in turbulent environments. Supported by post-doctoral researchers with the Structured Photonics Research Group, the student will complete real-world testing of these schemes and will potentially be integrated into prototype communication systems for BT.

Further, working with the University of Frieberg, the student will explore the creation of new spatial mode sets that have increased resilience to turbulence and develop new optical techniques for the demultiplexing of information encoded with these new types of optical modes.

These technologies will have direct application within the research field of optical communications, but will also provide new adaptive optics schemes that could be used within remote sensing and imaging systems that operate over long-distances. Further, environment sensing using spatially shaped light has become a recent hot topic, where the advances made within this PhD project will have a considerable impact on this emerging field.

This project is aligned with the £1.3 m EPSRC project "High Dimensional Wireless Passive Optical Networking for Access Deployment (PON-HD)," that is in collaboration with Aston University, University of Frieberg, and Nokia Bell Labs.

Complementing our Pathways to Impact document, here we state the expected real-world impact, which is of course the leading priority for our industrial partners. Their confidence that the proposed CDT will deliver valuable scientific, engineering and commercial impact is emphasized by their overwhelming financial support (£4.38M from industry in the form of cash contributions, and further in-kind support of £5.56M).

Here we summarize what will be the impacts expected from the proposed CDT.

(1) Impact on People
(a) Students
The CDT will have its major impact on the students themselves, by providing them with new understanding, skills and abilities (technical, business, professional), and by enhancing their employability.
(b) The UK public
The engagement planned in the CDT will educate and inform the general public about the high quality science and engineering being pursued by researchers in the CDT, and will also contribute to raising the profile of this mode of doctoral training -- particularly important since the public have limited awareness of the mechanisms through which research scientists are trained.

(2) Impact on Knowledge
New scientific knowledge and engineering know-how will be generated by the CDT. Theses, conference / journal papers and patents will be published to disseminate this knowledge.

(3) Impact on UK industry and economy
UK companies will gain a competitive advantage by using know-how and new techniques generated by CDT researchers.
Companies will also gain from improved recruitment and retention of high quality staff.
Longer term economic impacts will be felt as increased turnover and profitability for companies, and perhaps other impacts such as the generation / segmentation of new markets, and companies receiving inward investment for new products.

(4) Impact on Society
Photonic imaging, sensing and related devices and analytical techniques underpin many of products and services that UK industry markets either to consumers or to other businesses. Reskilling of the workforce with an emphasis on promoting technical leadership is central to EPSRC's Productive Nation prosperity outcome, and our CDT will achieve exactly this through its development of future industrially engaged scientists, engineers and innovators. The impact that these individuals will have on society will be manifested through their contribution to the creation of new products and services that improve the quality of life in sectors like transport, dependable energy networks, security and communications.

Greater internationalisation of the cohort of CDT researchers is expected from some of the CDT activities (e.g. international summer schools), with the potential impact of greater collaboration in the future between the next generations of UK and international researchers.