Study of New Borate Crystal for Ultraviolet Light Generation

主要研究结果如下：在2800 mJ的输入下，分别获得了600 mJ和320 mJ的266 nm和213 nm的紫外激光输出，这是迄今为止纳秒脉冲Nd：YAG激光器非线性光学频率转换产生的最高紫外激光能量。在这项工作中没有应用晶体温度控制。观察到了良好的输出稳定性和圆形光束图案。利用CLBO晶体实现了高功率全固态紫外激光器，研究了掺杂对晶体各项性能的影响。结果表明，Rb掺杂可以缩短CLBO晶体的倍频截止波长（lc），如从10mol%Rb掺杂（Rs/Cd=0.1）熔体中生长的晶体，lc缩短了2nm。然而，Rb掺杂使CLBO更加脆弱。K和Na掺杂也是如此。另一方面，Al的掺杂可以提高CLBO的力学性能。每个数据点表示从每个样品上的多个压痕获得的平均值。未掺杂的CLBO的硬度对于（100）和（001）表面分别为270和180，而掺杂1%Al和掺杂5%Al的CLBO的值对于（100）表面分别为290和310，对于（001）表面分别为220和230。实际上，掺Al的CLBO晶体在多晶时并没有开裂，掺Al的CLBO晶体的吸湿性能变差。将未掺杂和2%Al掺杂的CLBO晶体溶解在20%水和80%甘油的溶液中，研究了掺杂对晶体耐水性的影响。在实验过程中，样品被浸泡在溶液中。该实验表明，Al掺杂的CLBO比未掺杂的CLBO更难溶解。

The results obtained in this research are summarized as followings.We have obtained 266 nm and 213 nm output with a pulse energy of 600 mJ and 320 mJ,respectively, from the input of 2800 mJ.To the best of my knowledge, these have been the highest ever generated UV laser energy through NLO frequency conversion of nanoseconds pulsed Nd : YAG laser. There were no crystal temperature control applied in this work. Excellent output stability and rounded beam pattern were observed. High power all solid state UV laser via CLBO crystal is realized.Effect of doping on the various properties has been studied. It was found that Rb doping could shorten CLBO's SHG cutoff wavelength (lc), for example the lc became 2 nm shorter for the crystal grown from 10 mole % Rb-doped (Rs/Cd=0.1) melt. The Rb doping, however, has made CLBO more fragile. This was also the case for the K and Na doping. On the other hand, the Al doping could give rise to an enhancement of mechanical properties of CLBO.The Vickers hardness as a function of the Al/Cs ratio in the melt. Each data point represents an average value obtained from a number of indents on each sample. The hardness of undoped CLBO was 270 and 180 for (100) and (001) surfaces, respectively, while values for 1% Al-doped and 5% Al-doped CLBO were 290 and 310 for (100) and 220 and 230 for (001) surfaces. Actually, the Al-doped CLBO crystals have not been cracked even when they were the polycrystalline.It was found that the hygroscopic nature of CLBO become less by the Al doping. The undoped and 2%Al doped CLBO crystals were dissoved in the solution of H_2O (20%) and glycerin (80%) in order to investigate the effect of doping on resistance against water. The samples have been dipped in the solution during experiment. This experiment has shown that the Al-doped CLBO is less soluble than undoped CLBO.