Property Optimization And Experimental Investigation Of High Power Solid-State Laser

Solid-state lasers with high output power and high beam quality have been wildly usedin the field of materials processing. The thermal effects caused by the optical pumpinginduce a degradation of the beam quality and limit the maximum attainable output power.The main contents of this dissertation are focus on how to get high output power, how toachieve high beam quality and the key technology of laser diode (LD) side-pumpedsolid-state lasers. First, the dynamics characteristics of solid-state lasers were studied by using opticalmatrix and the relationship between the stable range of the lasers and the parameters of theresonators was derived. The result has been testified through experiments. The concept of resonator parameter p was put forward, and the laser beam parametersof a resonator, such as far-field divergence, waist of laser beam and the beam productparameter (BPP) was deduced. The laser beam parameters of some special resonators werecalculated and the beam quality of different resonators were compared. The theoreticalanalysis shows that the quality of the laser beam is proportionally to the inverse of stablerange of resonators, means large stable range cause poor beam quality, or large value ofBPP. The dynamic characteristics of multirods resonators were studied and the stable rangeof multirods resonators were given in details. If a suitable arrangement of rods and mirrorsis used, the output power increases proportionally to the number of rods. The largest rangeof stable oscillation is obtained from a symmetric plane-plane resonation, in which thedistance between two rods is twice as the mirror-rod distance. And the stable range increasewhen the mirror-rod distance reduces. The maximal output power of 840W was achievedwith two rods system and 970W with three rods system in the experiments. The operating characteristics of the LD were measured. The central wavelength of theradiation of LD shifted to the long wave direction with the increase of temperature ofcooling water and the operating current. The mathematic model of the distribution ofpumping light in the Nd:YAG were established and the pumping light distribution of IIIdifference pumping parameters were calculated by ray tracing. Three pump cavities of LD pumped Nd:YAG lasers were designed and the outputpower were 37W, 170W and 800W separately. The maximal optical to optical efficiency of37% was achieved.