Mini laser bars

The latest generation of mini laser bars from Osram Opto Semiconductors gives eight in the 910-1020 nm wavelength. Their output and beam parameters have been closely matched so that the beam, which leaves the small laser aperture at a defined angle, can be perfectly coupled into a small fibre core diameter with a restricted acceptance angle.

The bars have been optimised for fibre injection.

The high brilliance of this laser bar has been achieved by the VLOC epitaxial structure (very large optical cavity) and mirror-coating technology.

The bars are available in various application-specific product families, with fill factors of 10-20% and typical efficiencies of up to 65%. In addition to pumping fibre lasers, the bars are also used for direct micro-material processing, such as marking and micro-welding.

The brilliance of the mini laser bars is exemplified by the SPL BF series which has a fill factor of 10% and provides an output of 8 W per emitter at an emitter width of 100 µm, with a slow-axis divergence of <7° (the value applies to 95% output).

The maximum output compatible with long life is around 12 W per 100 µm emitter. With five emitters, the beam parameter product is 15 mm x mrad. With the aid of simple optics, the light from several mini laser bars can be coupled into a fibre with a core diameter of 200 µm and a numerical aperture of 0.22.

In this way, outputs from the fibre in excess of 200 W can be achieved.