本文采用商用532 nm激光器作为基频光源,利用偏硼酸钡(β-BBO)晶体进行外腔倍频,实现了266 nm连续激光的高效输出.文中详细模拟了BBO晶体中的束腰形状对倍频效率的影响,仿真和实验结果均表明椭圆高斯光束可以有效改善走离效应,提高倍频转换效率.通过优化蝶形倍频腔,可以使椭圆高斯光束在腔内共振,当1 W基频光输入时可输出约180 mW的266 nm紫外连续激光,倍频转换效率达到18%.
The 266 nm continuous-wave coherent radiation is generated by the second harmonic generation of a β-BBO crystal placed inside an external enhancement cavity. Its fundamental beam is a 532 nm laser from commercial production of Coherent Company. Impact of focusing shape of the crystal on the conversion eficiency is simulated detailedly.Theoretical and experimental results show that the elliptical focusing can decrease the walk-ofi efiect and improve conversion eficiency of the second harmonic generation(SHG). We obtain experimentally the 266 nm radiation output of 180 mW with elliptical focusing in a BBO crystal using bowtie cavity when the fundamental wave input 1 W. The SHG conversion eficiency reaches 18%.