2-D layer structure of index in KDP crystal and creation of diffraction grating

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The rapid growing method of water-soluble crystals has been developed. In order to keep a controllability of crystal growth, an automatic growing technology was established by measuring a super-saturation of the solution. The growth rate was increased from 1-2 mm/day in a conventional method to 50 mm/day in the rapid growth method.A selective inclusion of an ionic metal as an impurity in the crystal, such as iron ion, has been studied in the rapid growing method in which a growth rate has been controlled in time. As a result, KDP crystal has been found having a layered structure of index in an a-axis. But, a crystal structure of KDP shows needle-like one at a growth with a high impurity level in a solution.The two dimensional structure of index in a crystal has been achieved of several micron thickness. Optical parameters were investigated as a diffractive optic element. The theoretical properties of a transmission or reflective grating were summarized with a diffraction efficiency, wavelength matching, and allowance of the diffraction.The diffraction effect by layered structure of index was measured in an experiment showing a several-microns structure, then suggesting that 10^<-4>□ 10^<-5> index mismatching was needed for an efficient diffraction.The thermal shock parameter of KDP was measured for increasing strength of crystal at using an average power condition.In conclusion, the basic technology and knowledge have been established for a development of the diffractive optics in use at power laser system such as pulse compression, so on.