Study On The Output Characteristic Of High Power Long-Pluse Solid-State Laser

With the development of laser technology, solid-state lasers have been widely used in laser medicine, laser chemistry, material processing, scientific research and other aspects. Solid-state lasers with high output power and high beam quality are widely used in the field of matel materials processing industry to cut and weld. Becacuse the factors of laser rod material etc, signal-stage laser's output power is limited. The laser need one or more amplifiers to increase the output power when it can not meet the requirements in sometimes. In this paper, we did some research of 600W long-pulse solid-state lasers, it contents three main aspects.The first, we did theoretical analysis and calculation, including: the impact of device parameters and cavity-shape on output laser beam, output Gaussian beam waist radius and far-field divergence angle, the impact on collimation ratio of dynamic changes in active laser alignment system, confirm the largest collimation ratio, we found that the alignment effects of active laser alignment system is better than the passive alignment system. calculated the extraction efficiency in different of input power.The second, according to the demand,we designed the structure of 600W long-pulsed solid-state laser, which contented a laser resonator and an amplifier stage. The resonator cavity contents a plano-concave mirror and a plane mirror and a Nd: YAG rod. Plus xemon lamp, traveling wave amplication. Use thermal lens effect of laser rod, we can make a active laser beam alignment system which use the amplifier stage and a long focal convex lens.The third, build a laser system base on the structure designed. debugging and experiment, contents: measure the thermal focal length of Nd: YAG rod, the output power of the resonator and the amplifier stage, the far-field divergence angle of output laser beam from resonator and it after the collimation system. Under the condition of single-stage pumping 13.2kW, we measured the maximum output power of oscillator stage is 320w, the electro-optical conversion efficency is 2.42%, the output power of amplifierstage is 628w, the total electro electro-optical conversion efficency is 2.38, the result meet the design requirements. Experiments result show that the amplifier stage make the beam quality go bad.