Study on directional rapid growth and properties of 90% DKDP crystal

•There is pyramid-prism boundary in DKDP grown by “point-seed” rapid growth method.•A new crystal carrier with no shielding was used to grow DKDP crystal.•Z-plate crystal was used as the seed.•DKDP with 90% deuterium concentration was grown by directional rapid growth method.•The crystal of the sample taken has no pyramid-prism boundary. Due to the obvious pyramid-prism boundary in the deuterated potassium dihydrogen phosphate (DKDP) crystal grown by “point-seed” rapid growth method, the crystal uniformity and utilization rate were poor. In this paper, a DKDP crystal with deuterium concentration of about 90% has been grown using a new crystal carrier, and its deuterium concentration, extinction ratio and transmission spectrum have been measured. At the same time, the optical uniformity of this crystal was compared with that grown by the “point-seed” crystal rapid growth method, and the influence of these two methods on the pyramid-prism boundary of the crystal was studied. The result showed that the average deuterium concentration of the directionally grown DKDP crystal was 90.27%, which met the requirements of the experimental plan. Meanwhile, it was shown that the extinction ratio was up to 4623:1, and both the pyramidal sector and the prismatic sector of the crystal had good transmission performance. The optical uniformity test chart indicated that there was obvious pyramid-prism boundary in the crystal samples obtained by “point-seed” rapid growth method, while there was no pyramid-prism boundary in those by directional rapid growth method.