Experiment And Numerical Simulation Of KDP Crystal Grown By The Method Of Temperature Reduction

KDP crystal, as one kind of non-lineal optical material with good qualities, has been applied widely to the high technology fields such as laser frequency conversion, electrooptical modulation, optic switch and so on. Big-sized KDP crystal is the preferred material for ICF (Inertial Confinement Fusion), other materials with better comprehensive performance compared with KDP crystal can not be gained up till now.Because of its spreading usage in these fields, more high-quality KDP crystal is urgent needed. With the development of ICF technology, USA prohibits the export of relative technology and materials. In the international markets the big-sized and high-quality KDP crystal falls into short of supply.The focus of the research on KDP crystal in recent years is trying to increase KDP growth rate, shorten its growth cycle and decrease its cost at the precondition to assuring its high optical quality. The method of temperature reduction is the usual method of KDP crystal growth. It is very important maintaining an appropriate rate of temperature reduction in order that the solution is staying in metastable zone during the period of growth. So, in the process of crystal growth, an appropriate supersaturation of the solution needed be considered pivotally.In this paper, the following results have been obtained by KDP crystal growth experiments and numerical simulation.The initial temperature of solution and rate of temperature reduction have effects on the quantity and rate of crystal growth. Solvent evaporation will accelerate growth but lower its quality. So the vessel of growth solution should enable closed, growth solution should be controlled appropriately by the rate of temperature reduction.The stability and purity of the growing solution have more notable influence on growth rate and quality. The pH value of the growing solution changes the morphology of the grown crystal. pH=4.5 is the appropriate value for KDP crystal growth from solution.The distribution of crystal surface supersaturation trends gradually decreased from the edge to the center position of the crystal. On the same conditions, supersaturation will be lower with the growth rate increasing and supersaturation will be increased with the rotation speed of the seed crystal increasing.