For its SPL BF98-40-5 laser bar Osram Opto Semiconductors has optimised the chip design in terms of beam quality, resulting in a wavelength of 976 nm and high brilliance of 3 W/mm*mrad (per millimetre and per solid angle) at an optical output of 44W.
The laser bar is 5 mm wide and consists of five emitters, each 100 µm wide and each with cavity length of 4 mm. Brilliant laser sources generate a narrow beam of light with extremely small beam divergence and high power density. The lateral divergence of the beam emitted by the SPL BF98-40-5 is between 6° at 30W and approximately 9.5° at 60W, its maximum output. This divergence was calculated for the portion of the laser beam containing 95% of the optical output power. With its excellent electro-optical efficiency of 65% at 44W, the laser diode reduces the level of cooling needed for the laser diode and improves the efficiency of the entire system as well as the ageing stability.
The beam quality of a laser is a crucial factor for coupling laser light into optical fibres. A brilliant light source, as guaranteed by the SPL BF98-40-5, simplifies the design of the optical system and provides more cost-effective systems. Fibre-coupled diode laser systems are used predominantly in the automobile industry for vehicle chassis welding, soldering and coating as well as for pumping fibre lasers. The wavelength of 976 nm is suitable for pumping ytterbium-doped fibre lasers in particular, which can be used for cutting metal thanks to their excellent beam quality.
Osram Opto Semiconductors defined the fundamental principles for developing the high-power high-brilliance laser bar within the HEMILAS project sponsored by the Germany Ministry for Education and Research (BMBF).