NATAL project had as its primary targets the development of new semiconductor materials and laser technologies for generating high-brightness visible and ultraviolet radiation. The key technologies deployed in the project concentrated on optically pumped semiconductor-disk laser (OP-SDL) architecture, often also referred to as the VECSEL (Vertical-External-Cavity Surface Emitting Laser). Basic research and development, but also field trials and demonstrations, have been developed over a period of three years. This work has been supported by the European Commission with 2.7 million in funding under the 6th R&D Framework Program (FP6). Total investment in the project, including contributions from companies, was 4.1 million .
The project was coordinated by the Optoelectronics Research Centre (ORC), Tampere University of Technology Finland, and was carried out as a collaboration between some of the leading European academic institutions and industrial partners. This research collaboration was driven by novel semiconductor gain material grown by the ORC and the Technical University of Berlin (Germany). Generation of record-high power visible light at the Institute of Photonics, University of Strathclyde (UK), was amongst the highlights of NATAL. For the first time ever, blue laser diodes were used for direct optical pumping of red SDL material highlighting new avenues for the development of compact and powerful lasers with emission in the visible and the UV. Chalmers University of Technology has developed and advanced 3-D simulation tool that takes into account electro-optical and thermal properties of the gain chip but also the effect of external optical elements. These advances represent a major breakthrough in terms of theoretical work on VECSEL design and simulation. Using support provided by OptoCap Ltd., Livingston (UK) and EpiCrystals Ltd. (Finland), the partners achieved the current world record in optical power at 1220 nm. These SDLs could be frequency converted to generate more than 4.5 W of high-brightness radiation at 610 nm. In the project, TOPTICA AG of Munich (Germany) developed early stage demonstrators allowing single frequency operation, tunability, frequency conversion and system integration. As the most eminent commercial result, project partner OSRAM Opto Semiconductors in Regensburg (Germany) has already started to develop VECSELbased technology for low power RGB projection, while EpiCrystals has entered the commercial field with its proprietary DeCIBEL technology.
The NATAL consortium has surely propelled this very exciting field of laser research into new spectral regions, and new power levels in the NIR spectral range, but has also opened up a variety of technologically interesting lines in the visible spectrum, with output powers of up to a few watts demonstrated/achieved through use of compact frequency-doubling set-ups.
NATAL project has helped to generate a significant amount of knowledge and new technologies in Europe in the field of optically-pumped vertical-external-cavity surface-emitting lasers. The industrial partners of NATAL have showed significant effort towards realizing compact volume production lasers based on the technologies developed within the project. In the project TOPTICA developed early stage demonstrators allowing single-frequency operation, tunability, and frequency conversion in a compact system. The most important impact on commercialization of VECSEL technologies is expected to be made by OSRAM, which has engaged in the development of VECSEL-based technology for low power RGB projection. EpiCrystals has also entered the commercial field with its proprietary DeCIBEL technology, a complementary but yet related platform to a VECSEL. At the scientific level NATAL enabled breakthrough results in fabrication of novel compound semiconductor materials application, new laser architectures, and new operation wavelength. First in the world demonstrations of QDs VECSELs, as well as compact red and UV VECSELs have open new research areas. In particular the QD VECSEL approach is currently pursued within the Fast-Dot IP project.