Rapid growth of a long-seed KDP crystal

To reduce the seed length while maintaining the advantages of the cuboid KDP-type crystal,a long-seed KDP crystal with size 471 mm×480 mm×400 mm is rapidly grown.With almost the same high cutting efficiency to obtain third harmonic generation oriented samples,this long-seed KDP-type crystal can be grown with a shorter seed than that of the cuboid KDP-type crystal.The full width at half maximum of the high-resolution X-ray diffraction of the(200)crystalline face is 28.8 arc seconds,indicating that the long-seed KDP crystal has good crystalline quality.In the wavelength range of 377–1022 nm,the transmittance of the long-seed KDP crystal is higher than 90%.The fluence for the 50%probability of laser-induced damage(LID)is 18.5 J/cm^2(3 ns,355 nm).Several test points survive when the laser fluence exceeds 30 J/cm^2(3 ns,355 nm),indicating the good LID performance of the long-seed KDP crystal.At present,the growth of a long-seed DKDP crystal is under way.