The Study On Growth In All Three Dimensions And Optical Homogeneity Of DKDP

Due to interesting electrical and nonlinear optical properties, DKDPcrystal is a very important optical component material of high power laser.At present, its optical quality and growth rate have become the hot-point. Depending on the analyses of growth-kinetics and affecting factorsof growth rate in crystal growth experiments, growing crystals insolutions by temperature reduction at a normal temperature through manyexperiments, we obtained the growth techniques as follows: to growcrystals in all three dimensions with point seeds(4× 4×1mm3), the highestreducing temperature initiated at 45.3℃, pD of solution is 3.8-4.3, thelowing rate of temperature was 0.2-1.5℃/day, and the highest averagegrowth rate was 3.1mm/day. We got DKDP crystals with extinction ratio from4115:1 to 6944:1,and laser damage threshold of 2.7-3.7GW/cm2 , It can beseen from the results of experiments, at the growth rate of 0.8-3.1mm/day,growth rate has no effect on optical homogeneity, the purity of rawmaterials has pronounced effects on optical homogeneity and otherproperties. Synchrotron radiation X-ray white-beam topography has been used toinvestigate the defects of crystals, the samples' thickness is 0.4mm,exposure time is 5-7s.Distance between the sample and the film is 90mm.Onthis condition, the number of Laue spot is right, and the film is clear.Put the films under the optical microscope, some defects have beenobserved ,such as striation, inclusions, cracks and dislocation, and soon. The reason of these defects was studied, then influences of variousgrowth conditions and growth phases on crystals integration are discussed,and foundations are provided for perfecting crystals growth techniques. To improve optical homogeneity of crystals, the grown crystals have - II -Abstractbeen treated with annealing at the temperature of 80℃ and 100℃, therising and lowing rate of temperature was 3℃/h, keep the temperature nochange at the high temperature for 24 hours. Transmittance and extinctionratios are both improved after annealing, but damage threshold has nochange. The mechanism of the annealing was discussed elementarily. In a word, growth conditions in all three dimensions and opticalhomogeneity of DKDP crystals were studied systematically, and manymeaningful results were obtained, but some questions still need furtherresearches.