Beam shaping and fibre coupling of high-power diode laser arrays

A technique for coupling the radiation of a high-power diode laser bar into one multimode fibre with high efficiency, easy alignment requirements and low manufacturing costs is demonstrated using a single fibre with 400 mu m core diameter. The principal item of the fibre-coupling system is a pair of micro step-mirrors - a novel design for beam shaping. The overall efficiency from diode-laser to fibre is 71 per cent with 20 W cw laser power through the fibre. Polarisation and wavelength multiplexing renders the system scaleable to higher output power which makes it highly suitable for material processing and pumping of lasers.