High-average-power YAG lasers and applications

A novel multi-rod cw Nd:YAG laser with 4 kW output power through an optical fiber has been developed. We adopted a unique YAG rod arrangement which minimizes the distance between adjacent rods. By using such a resonator, the laser output power of 4.8 kW was extracted from the laser resonator at an oscillation efficiency of 3.9%. The fiber power transmission with a fused silica fiber of 1.0 mm diameter is possible for the delivered laser power of 4.4 kW with transmission efficiency of about 92%, which is the same as a theoretical reflection loss at end surfaces. Welding experiments using the developed 4 kW YAG laser with a fiber- connected multi-joint robots showed excellent performance of 10 mm penetration for stainless steel welding and of more than 4 mm penetration for aluminum alloys.