Study On The Growth And Properties Of KTP Crystals

Potassium titanyl phosphate(KTP for short) crystal is an important member of the phosphate nonlinear optical crystal family.KTP,with its larger nonlinear exponent,a higher laser damage threshold resistance,relatively stable chemical proprieties,rather high frequency-doubling transformation efficiency,and a low cost,is one of the best crystals in terms of the comprehensive properties.To meet the urgent needs of KTP in reality,the experiment is aimed to produce the large-sized single crystals with high optical quality under the available conditions at the moment and figure out its growth conditions and specific growth habit.Thus,the slow-cooling method of high temperature solution is adopted and the KTP crystal is grown in the solution with the temperature ranging from 600℃to 1000℃under the normal pressure.As for the seed crystal grown in the direction of [010],the crystal follows the model of rotation-stop-reverse rotation.According to growth condition,we adopt proper cooling programs which carry out crystal growth and the crystal is taken out through annealing at last.Through the causal analysis of newly-produced KTP crystals why the defects such as inclusions,steps,cloud layers and cracking during their growth process,and a careful observation and analysis of those dislocation etch pit,growth striation and growth hills of different crystal planes by using chemical etching method,the crystal perfection is thus studied.During the growing process of pure-KTP,two doped-KTP were also grown,one of which is Al³⁺with ten percent tool and the other is Al³⁺ with seven percent tool and KF with one percent tool.From the testing and accounting of related characteristics such as lattice parameter,the distribution coefficients,ultraviolet-visible-infrared trans-spectral,powder frequency-doubling,and laser damage threshold,ect.Of these three samples under different testing environments,it turns to be that the doping does not cause any prominent changes of the parameter of crystal structure and the imposes a rather weak impact on ultraviolet-visible-infrared trans-spectra,which demonstrated that the amount of doping ion is not so much that could cause big changes in the crystal structure.The powder frequency-doubling of the Al³⁺doped-KTP crystal shows that its SHG is increased than that of the pure KTP crystal on average,which means the doping of Al³⁺ has an impact on the performance of the crystals.This thesis conducts a relatively systematic research on the growing technology, propriety and performance of the KTP crystal,through which greatly enriched the theoretical foundations and practical experience,however,some issues need further and deeper discussion.