Hisatada Machida

1.7kW high efficiency LD pumped Nd:YAG laser

Material processing kilowatt-class LD pumped solid-state lasers have been actively developed to be used in such industries as automotive, aerospace, electronic and so on. In this development, the key technologies are the following two, i.e. development of high power LD possessing high efficiency and thermal management within the laser crystal.

2.5-kW slab Nd:YAG laser using a 400-mm-long crystal bonded by optical contact method

The optical contact method has been developed to obtain a large volume slab Nd:YAG crystal for achieving a multi-kW output power. The bonded crystal with the dimension of 6 X 25 X 402 mm3 (tip to tip) is mounted in a single laser head and is pumped with four krypton arc lamps. In continuous wave (CW) operation, the maximum output power of 2480 W, the overall efficiency (eta) E-O of 4.0% and the slope efficiency of 5.5% have been obtained. A beam quality which is defined as the product of full divergence angle and diameter of the beam waist is better than 10 mm (DOT) mrad and 80 mm (DOT) mrad in the directions of the thickness and the width of the slab, respectively. The output laser beam was transmitted through a GI type 600 micrometer-core optical fiber completely. This configuration has realized a simple resonator laser producing high processing performance.