We have achieved a high-quality beam generation wih highly efficient quasi-cw Nd:YAG laser over 1-kW with a novel side-pumping configuration using micro-lens free diode-stacks as a part of "Advanced Photon Processing and Measurement Technologies" program. We have demonstrated a power scaling of Nd:YAG rod laser over 1 kW while maintaining high-beam-quality and high-efficiency by cascaded-coupling of two identical bifocusing compensation resonators. Laser power of 1050W was obtained with the beam quality of M2 = 8 at the electric-to-optical efficiency of 23%. In this work, we also demonstrated the focusing ability of less than 50 μm diameter on the focal plane by using a f50mm lens (N.A. 0.2). Moreover, with driving AO-Q switch in burst mode operation, over 2MW pulse peek is demonstrated.
We have achieved a high-quality beam generation with highly efficient quasi-cw Nd:YAG laser over 1-kW with a novel side-pumping configuration using micro-lens free diode-stacks as a part of "Advanced Photon Processing and Measurement Technologies" program. We have demonstrated a power scaling of Nd:YAG rod laser over 1-kW while maintaining high-beam-quality and high-efficiency by cascaded-coupling of two identical bifocusing compensation resonators. Laser power of 1050W was obtained with the beam quality of M2 = 8 at the electric-to-optical efficiency of 23%. In this work, we also demonstrated the focusing ability of less than 50 μm diameter on the focal plane by using a f50 mm lens (N.A. 0.2).
KEYWORDS: Nd:YAG lasers, Diode pumped solid state lasers, Copper, Laser drilling, High power lasers, Solid state lasers, Laser processing, Rod lasers, Resonators, Neodymium
We have proposed a highly efficient and high-brightness quasi-cw Nd:YAG rod laser with a novel-side-pumping design using micro-lens free diode-stacks. We achieved 320W output power with 28-% electrical-to-optical efficiency, which is, to our knowledge, the highest efficiency reported for diode- pumped solid-state lasers. We generated the high quality beam of M2equals4 with the output power of 500W while maintaining the electrical-to-optical efficiency of 20%. We also demonstrated through-hole formation of 1mm thick copper plate using the high brightness laser beam and successfully obtained round holes with the diameter of less than 40 micrometers .
We demonstrate a novel method of equalizing laser diode beam into circular beam. The method uses the twist effect of graded index(GI) fiber optics. An asymmetric laser diode beam with the beam qualities of M2=500 in the slow axis and M2=4 in the fist axis is successfully converted into a symmetric circular beam with the beam quality of M2=175. The circular output beam with 92% coupling efficiency is obtained by using a 5m long GI1200 fiber for 2W laser diode array. We have Ibund that the required minimum length of G11200 fiber is 550mm for circular beam equalizing. We extend the experiments to higher power source with higher asymmetric beam qualities of M2=3000/M2=4. By using a large core diameter ofGI10000 fiber, the higher asymmetric beam is not converted into a perct symmetric beam. We consider that the length is too short Ibr this large core fiber. Since the GI1200 fiber required 550mm, the GI10000 fiber should require at least 4583mm, however, the fiber length is limited to 500mm because ofthe production matter. By slightly bending the fiber, however, we have succeeded in generating symmetric beam with improved beam quality of M2=2000. The average beam quality is preserved when the asymmetric ratio is not high and the beam quality degradation ratio is investigated up to asymmetric ratios of 750.
We have proposed a highly efficient and high-brightness quasi-cw Nd:YAG rod laser with a novel-side-pumping design using micro-lens free diode-stacks. We demonstrated 320-W output power with 28-% electrical-to-optical efficiency, which is, to our knowledge, the highest efficiency reported for diode-pumped solid-state lasers. We also achieved the beam quality of M2 =4 with the output power of 500 W by introducing a bifocusing compensation resonator. The corresponding electrical-to-optical efficiency was 20 %.
We have demonstrated a highly efficient quasi-cw Nd:YAG laser with a novel side-pumping configuration using micro-lens free stacked-diode-bars. In this configuration, the fast-axis of the diode bars is arranged in parallel to the rod axis which means highly efficient P-polarization pumping of the Nd:YAG rod. The pumping beams are coupled into a cylindrical diffusive reflector by using wedge lenses (1-dimensional lens duct). The pump radiation in the slow axis direction is focused by the cylindrical surface of the wedge lens, and the radiation in the fast axis direction is transferred by the total internal reflection. Six micro-lens free diode bars are arranged around the Nd:YAG rod. The transfer efficiency of the wedge lens was 89%. Laser power of 270 W was obtained at the beam quality of 20 mm mrad at the electric efficiency of 18.4%. The experimental results are well explained by calculations and we consider further enhancement of the efficiency is possible by optimizing the diffusive cavity design.
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