FIBRE-LASER PUMPED DIAMOND RAMAN LASERS FOR LIDAR AND CLEAR PLASTICS WELDING

Diamond and fibre are a natural match that provides a platform to take high-power lasers into hitherto unattainable parameter regimes and to serve new applications. Though attractive in its simplicity, this area remains largely unexplored. Here, we propose a partnership that will enable high-impact applications through careful investigation of the underpinning device science. This will lead to fibre-pumped diamond Raman lasers with properties tailored to applications in LIDAR and clear plastics processing. We aim to lay the foundations for this to become the preferred approach for a number of important laser applications.

Fibre lasers are the laser of choice from medicine to materials processing thanks to their reliability, low cost of ownership, proven performance, and outstanding power scalability. While moderate laser parameters and standard wavelengths suffice for many applications, many more require better beam quality, narrower linewidths, specific wavelengths, or well-controlled high-energy pulses - but still at hundreds of watts of output power. Fibre lasers can only rarely simultaneously satisfy these requirements. In this project, we aim to overcome these generic limitations of fibre sources by employing diamond to shift fibre lasers further into infrared via stimulated Raman scattering (SRS) with simultaneous brightness enhancement and, in the case of pulses, spectral narrowing towards the transform-limit.

The UK is established as a world leader in fibre laser research and has played a leading role in pioneering the use of diamond in Raman lasers. Both fibre lasers and diamond are recognized as being superbly power scalable thanks to superior optical and thermal properties. Our approach will harness the advantages of fibre systems - efficiency, compactness, and reliability - while modifying their output to better address key industrial challenges. While the combination of fibre and diamond is a platform solution that can address a wide range of wavelength-specific applications, especially in the near IR range, in this project we aim to prove the technology in two areas that are important for our industrial partners. This proposal will deliver a new type of laser that is uniquely capable of the combination of power, brightness, spectral purity and wavelength required for industrially important applications in LIDAR and clear plastic processing.

It will be vital for the project to engage with a wider industrial audience to ensure potential beneficiaries can access the outcomes of the project and feed into it. Trade press articles will be written - for Laser Focus World and Photonics Spectra internationally, and the magazine of the Association of Industrial Laser Users in the UK. The team will also present to industrially-orientated fora: both those oriented to laser firms (e.g. Photonics West) and the end-users (e.g meeting of the European and American wind energy associations). These will complement a workshop organised by the team at the end-point of the project. The team will also give presentations on company premises, building on recent well-received talks at Selex, Coherent, Element Six, M Squared Lasers and Thales.
The key objective of the impact plan is to build the team required to deliver economic impact. This engagement was at the core of the programme from the beginning. The required partners were identified by the investigators and they then played a key role in shaping the proposal to address systems-level requirements and market pull. At the component level, the key elements of the supply chain are covered by SPI Lasers, a fibre laser supplier, and Element Six, a diamond grower. At the technical level, the combination of the ORC and IoP teams provides coverage of the key technologies in fibre and Raman lasers. At a systems level, SPI Lasers and Thales Optronics already operate in the target markets of materials processing and LIDAR respectively. An active role for these firms is built into the work programme to ensure systems orientated requirements are addressed.
For the clear plastics processing strand, the team will work with SPI Lasers to build a proof-of-principle demonstrator that can be tested at the SPI test facility. On the LIDAR side, Thales has identified the compatibility of the laser design and component choice with the environmental demands on a LIDAR system as the critical hurdle to economic impact. Hence, the team will use Pathways to Impact funding to bring in specialist expertise from the Fraunhofer Centre for Applied Photonics (CAP) to analyse these aspects, with systems level input from Thales, and feed this back into the experimental design. Modelling and roadmapping using CAP's specialist facilities and expertise, in concert with systems-level guidance from Thales, will ensure the research passes through the 'gates' that UK industry typically applies to decide if a technology is sufficiently mature for it to pick up. This will put the coalition in a strong position to apply for industry-led funding (e.g. Innovate UK) to move towards the development of a fully engineered demonstrator. Subsequent to successful demonstrations of critical function, roadmaps for maximising impact will be prepared with input from all the relevant partners.