腔内倍频Nd^3＋：GdVO4／LBO深蓝456nm激光器的工作特性

Characteristics of Intracavity-Frequency-Doubled Nd^(3+)∶GdVO_4/LBODeep Blue 456nm Laser

在激光二极管(LD)抽运腔内倍频Nd3+∶GdVO4/LBO深蓝456 nm激光器中,为对比激光晶体掺杂浓度对倍频输出功率的影响,利用同样尺寸为3 mm×3 mm×2 mm,稀土离子掺杂原子数分数分别为0.15和0.25的Nd3+∶GdVO4晶体作为对比。实验中利用同样长为20 mm的线性直腔,在使用10 mm长、按基频光为914 nm方向切割的Ⅰ类相位匹配倍频晶体LBO,在抽运功率为2.85 W时,前者获得了输出功率为105 mW的深蓝456 nm激光,明显高于后者。通过对准三能级激光晶体的最佳长度分析表明,掺杂原子数分数为0.15的Nd3+∶GdVO4晶体与0.25的相比,其实际长度更加接近于最佳长度。通过对倍频晶体LBO的最佳切割角和温度控制等分析表明,利用针对914 nm基频光切割的LBO晶体在912 nm激光器中,其切割角的差别可以通过温控的改变得到补偿。

In the experiment of laser diode （LD） pumped intracavity frequency doubled Nd：GdVO4/LBO deep blue 456 nm laser, in order to examine the effect of different neodymium concentrations in laser crystal on output power of frequency-doubled laser, two Nd： GdVO4 crystals with the same size of 3 mm × 3 mm × 2 mm and different neodymium concentrations with Nd^3＋ ion atom fraction of 15% and 25% are compared. In the experiment , the same length of laser cavity of 20 mm and an I -type phase-matched frequency-duobled medium of LBO for 914 nm with the length of 10 mm were used, a output power of 105 mW was obtained at incident pumped power of 2.85 W in the former crystal. In experiment, the laser crystal with higher dopant concentration obtained lower output power relative to that with lower dopant concentration. Through analyzing optimal crystal length in quasi-three-level laser system, the actual length of the 15% Nd^3＋ doped crystal is closer to the optimal length compared with the other crystal. Through analyzing the accurate cut-angle of frequency-doubled medium and temperature control of LBO, the difference of cut-angle for 912 nm and 914 nm may be compensated by controlling the temperature.