Within the scope of the research project “BlauLas”, funded within the German photonic initiative “EFFILAS”  by the German Federal Ministry of Education and Research (BMBF), Laserline in cooperation with OSRAM aims to realize a cw fiber-coupled diode-laser exceeding 1 kW blue laser power.
In this paper the conceptual design and experimental results of a 700 W blue fiber-coupled diode-laser are presented. Initially a close look had to be taken on the mounting techniques of the semiconductors to serve the requirements of the GaN laser diodes. Early samples were used for extensive long term tests to investigate degradation processes. With first functional laser-modules we set up fiber-coupled laser-systems for further testing. Besides adaption of well-known optical concepts a main task within the development of the laser system was the selection and examination of suitable materials and assembling in order to minimize degradation and reach adequate lifetimes. We realized R&D blue lasersystems with lifetimes above 5,000 h, which enable first application experiments on processing of various materials as well as experiments on conversion to white-light.