Advanced Controllable Raman Lasers

Over the last decade, solid-state lasers have been the subject of great interest with a wide range of applications thanks mostly to their superior output-power-to-wall-plug efficiency. However, the limited availability of colours (wavelengths) produced by these lasers forces the user to compromise by utilising a wavelength that is not ideal for the targeted application. Laser systems based on a nonlinear process, called Stimulated Raman Scattering, offer a simple solution to this need. However, the performance and usability of these so-called Raman lasers have traditionally been limited by thermal distortions inherent to the nonlinear process.

This project will, for the first time, investigate the implementation of the adaptive control techniques - typically used in astronomy- inside Raman lasers to significantly alleviate this thermal issue. In this way, the behaviour and performance of the laser can be remotely controlled and optimised resulting in superior performance in terms of output power, beam quality and usability. This offers the prospect of several genuine breakthroughs including a range of world-firsts and world-records as well as the transfer of these laboratory-based systems into an engineering context.

These significantly enhanced systems will address a wide range of applications including astronomy, environmental monitoring, cosmetics and medicine. For instance, the treatment of a variety of skin diseases such as psoriasis or port wine stain removal will strongly benefit from this project.

Finally, knowledge transfer is an important feature of this project with a full strand of activity dedicated to it. The transfer of this technology will be performed within two high profile research groups at Macquarie University, Australia and at the University of Strathclyde. An industrial collaboration with M Squared Lasers will also take place, particularly targeting commercialisation of the final demonstrator.

The project aims to substantially alleviate the main limitation of solid-state Raman lasers (SSRL) enabling significant power scaling (>10W), improved conversion efficiency and automatic optimisation of the laser output. The project also plans to take SSRL from the research lab environment to an engineering context. Therefore, a new generation of SSRL offering a wide range of exotic and in-demand wavelengths while using common doped-dielectric laser materials will be developed. The proposed lasers will not only replace older generation systems but also trigger new uses. Beneficiaries include academic researchers in several disciplines, private companies developing and/or using laser systems, public sector workers in the medical field and their patients, and ultimately, the general public (due to the impact on environment, security and defence). Since the planned work is highly-likely to result in several commercially-significant developments, this project will be monitored and supported by RKES' experts in IP identification and exploitation. Assessment will be made, in an ongoing process, of the optimal IP protection approach.

First, academic and industrial researchers developing SSRL will directly benefit from the research. The potential for pushing back the main barrier in developing high power SSRL with outstanding quality has attracted interest from the world leaders in SSRL, Macquarie University, Australia (Dr. Pask). A new international academic collaboration will result and lead to the implementation of the final demonstrator in a laser platform at Dr. Pask's laboratories. Furthermore, the significant performance improvement and increased functionality of the laser systems will rapidly enable this relatively new and lab-based type of lasers to be used in a wide range of industrial and medical applications. This has been identified by M Squared Lasers who will, in particular, help him bring his research closer to the market.

More widely, the proposed laser systems will impact several fields.
First, the development of high power, compact, efficient yellow lasers with outstanding beam quality will allow the further development of already-existing phototherapeutic techniques as well as triggering a new range of treatments. Dermatological issues such as port wine stains or psoriasis can efficiently be treated with yellow lasers since radiation at this wavelength is absorbed by oxyhaemoglobin while being transparent to skin tissues. In this way, the capillary walls are heated until destruction (at ~70deg.C) and absorbed by the body's natural mechanism. Moreover, laser retinal photocoagulation will benefit from the proposed research. So, the development of efficient, reduced size, lower cost lasers emitting in the yellow waveband will enable phototherapy techniques to be installed in a wider range of hospitals reaching a larger number of patients. The lasers developed will also impact cosmetic applications such as tattoo and hair removal, liposuction and the treatment of benign epidermal pigmented lesions. In particular, the proposed laser sources emitting at ~1200nm of wavelength will match the peak absorption of adipose tissues enabling more efficient lipolysis than the common systems at 1064nm. This will enable a reduction of the duration and cost of the procedure.
The wavelength flexibility and pulse energy of the SSRL developed will enable their use in environmental applications such as the long-range monitoring of pollutant gases and leak detection in pipeline and gas storage facilities. In particular, SSRL could be implemented in a long-distance remote sensing system of HF gas, a by-product of Uranium decomposition in the air, and so, could be used to detect Uranium enrichment facilities. So, the project will strongly impact on security and defence.
Finally, the proposed visible lasers will represent an attractive option for producing laser guide stars used in ground-based telescopes.