Ultra-precision optical engineering with short-wavelength semiconductor disk laser technology

It has been 50 years since the first operation of the laser, yet there are still many new applications being made possible by continued innovation in laser technology. A range of exciting optical engineering techniques are currently being developed by scientists and engineers to achieve ever greater precision in sensing, manufacturing, and measurement: from the fabrication of nanometre-scale crystal structures created by laser light patterns to the probing of atomic energy levels to define the time and frequency standards used for communications and navigation. Such visible- and ultraviolet-based (short wavelength) research is very active; however, investigators are currently making do and having to become rather adept at converting current lasers with complex systems for beam shaping, amplification and frequency conversion which generally fall short of the desired wavelength, power and finesse, and confine this technology to the lab. This programme will develop a new class of simplified and tailored short wavelength laser systems in collaboration with these scientists and engineers in order to address a gap in the laser toolbox, dramatically improve capability, and bring these currently specialist techniques out of the lab to the level of widely deployed technology.The core laser technology for the optical engineering systems targeted will be semiconductor disk lasers (SDLs). SDLs are distinct from conventional high performance lasers in that the gain material is engineered on the nanometre scale. Rather than a laser crystal (millimetres long), a flow of dye, or a pressurised tube of gas, light amplification is provided by several quantum wells (QWs): ultra-thin (few nanometres thick) layers of semiconductor, positioned with nanometre-scale accuracy with respect to the light field in the laser. Aside from commercial advantages in terms of compactness, cost and wavelength flexibility, this set-up is fundamentally suited to the very high coherence, low noise laser performance required for ultra-precision optical engineering.Nearly all SDLs operate in the near- or mid-infrared regions of the spectrum; however, many more applications will open up if their full potential for visible and ultraviolet operation is realised. The unique capability in short wavelength SDLs that Dr. Hastie's team has developed over the past 5 years means that she is now in a position to push the technology to target genuine applications for wider benefit. She has identified UK and international research partners for the realisation of high finesse semiconductor laser systems in the visible and UV, together with end users at research institutions in the UK. The Challenging Engineering award will provide the platform necessary to lead this research network and address the identified challenges.Three different optical engineering systems will be targeted initially:* interference lithography - an effective, low-cost method of fabricating nanostructures over a large area and widely deployed in the fabrication of circuits in the semiconductor industry* ultraviolet spectroscopy - for measuring the concentrations of important atmospheric trace gases* optical clocks - for the improvement in time and frequency standards used for communications, satellite navigation and testing of fundamental physics.These areas are complementary in terms of the required laser engineering and performance, will achieve a step-change in capability through the application of short wavelength SDLs, and are sufficiently diverse to provide scope to actively pursue multiple promising research directions and applications, many not yet predicted.

In general the impact of any research will first be felt in academia, followed by take-up in industry, before making a measurable difference to society. The nature of this programme will speed up this transition as the systems will be engineered in collaboration with academic end users and co-located industrial R&D, and a network of further industrial contacts poised to exploit the commercial benefits. Dissemination in the academic community will be achieved via presentation of the results at international conferences and reporting in high impact journals. This work will be presented at the Conference on Lasers and Electro-Optics, Advanced Solid-State Photonics, and Photonics West - the main international events for the reporting of the latest advances in laser technology. In addition the Institute of Photonics (IoP) maintains a presence at exhibitions and trade shows, with stands at Photonics West and at Photonex. Papers will be written for high-impact journals such as Optics Express and Applied Physics Letters addressing a wide readership. Broader communication will be achieved via technological and industrial magazines. One of the most effective means of the communication of ideas, dissemination of results, and interaction with interested parties, is via a custom-built regularly updated website. At the beginning of the programme an online portal will be specially designed and launched for this purpose. The IoP has built a varied funding portfolio including collaborations with both small photonics companies and large multinationals such as Selex, BAE Systems, Samsung and Osram. Industrial relationships are built through the annual IoP Open Day, business seminars, KTN events and the IoP's Industrial Membership Programme. The application of these systems for sensing will be explored through the Strathclyde Sensors Network - an IoP led initiative with strong backing from Honeywell, Selex and Thales. We will actively work with these long-standing partners. The IoP will lead the new Technology and Innovation Centre at the University of Strathclyde which will co-locate academic research with industrial R&D labs, thus providing ample interaction and opportunity to ensure the systems developed are fully exploited. The IoP has a track record of actively managing the IP generated by our research with more than 50% of our patents having already produced commercial outcomes. At the beginning of the collaborative work, joint IP agreements will be drawn up and signed by the IoP, NPL and CUNY with additional interactions similarly managed when they arise. Only two companies worldwide currently make and sell semiconductor disk lasers, and they are both local with well-established links to the IoP: Coherent and Solus Technologies. Indeed, the latter is currently funding an infrared SDL project within our group. In addition, Glasgow-based M Squared Lasers is committed to the delivery of innovative solid-state lasers in order to meet the specific applications of customers. CEO Graeme Malcolm is a current collaborator on SDL technology and will provide funding for a studentship. Another local company, Gilden Photonics, is a rapidly growing SME that designs and manufactures optical spectroscopy systems. In conjunction with the University they have just launched the Hyperspectral Imaging Centre of Excellence. The group at the IoP is therefore in a strong position to exploit the relevant industrial contacts for the systems targeted. To further enhance our capability to engage with industry the position of Technologist was created at the IoP in order to quickly respond to collaboration opportunities. This position is dedicated to short-term projects, funded by industry, that enable fast feasibility studies of IoP research directed to industrial applications. Should the chance arise during the project to apply the SDLs and systems in further collaborations with industry, JEH will work with the technologist to manage this activity.