1.1kW high efficiency LD pumped Nd:YAG laser

Recently, the development of multi-kW all solid-state lasers for industrial applications has been evaluated for the energy saving characteristics. We report the laser oscillator using the LD pumped slab Nd:YAG producing the highest efficiency on the cooling condition of room temperature. The two-side pumping is generally used for realizing symmetrically distributed excitation and temperature in the crystal. However, there exist two demerits coming from the useless LD pump light which is not absorbed in the slab. The first demerit is the fact that this light does not contribute to laser oscillation and the second one that the same light degrades the performances of LDs locating on the opposite side. We have eliminated these demerits by employing the one-side pumping method in which LDs are located on one side of the slab and a highly reflecting mirror is located on the other side. Based on this concept, the LD pumped slab Nd:YAG laser has been developed using a 6 x 25 x 206mm(3) slab crystal. The average output power of 1109W and the peak output power of 4900W have been obtained with the optical efficiency of 40.6% and the electrical efficiency of 15.3% on the cooling condition of 299K.