Beam shaping laser diode array output for optical pumping and illumination

The typical output divergence of a laser diode bar is about 40 degrees X 10 degrees in the fast and slow axes, which can be difficult to optically couple into a rod or slab-shaped laser host. Depending on the distance from the laser host, a fast axis output of 7 degrees - 10 degrees may be acceptable. For side pumping a thin slab a fast axis output of 1 degrees or less may be required to achieve the desired absorption profile. We have recently lensed 8, 25, and 30 bar stacks of laser diode bars, which were used to side pump Nd:YAG. Not only was the output divergence of each bar required to be lens than 1 degrees, but also the output of each bar was required to be parallel. In most cases optically polished anti-reflection coated cylindrical lenses are used to obtain brightness and uniformity.