Nd:YVO_4/Cr^(4+):YAG被动调Q激光器输出特性的提高

Improvement of Cr^(4+):YAG Passively Q-switched Nd:YVO_4 Laser Output Characteristics

针对提高连续激光二极管抽运Nd:YVO4/Cr4+:YAG被动调Q激光器输出特性,进行了理论和实验研究。Nd:YVO4相对于Nd:YAG,具有受激辐射截面很大的特点,因此有利于连续运转,但是泵浦功率一定的情况下储能低,不利于被动调Q运转。基于被动调Q速率方程,分析了可饱和吸收体内光束截面积对输出特性的影响,提出了在谐振腔内加入扩束镜的新方法。放在谐振腔中的扩束镜让饱和吸收体内的光子数密度增大,因而可以提高被动调Q激光器输出特性。在Nd:YVO4/Cr4+:YAG被动调Q激光器试验中用倍率3的扩束镜,将峰值功率提高了一个量级以上,单脉冲能量提高了两倍以上。该方法也可以应用在其他被动调Q激光器中,以便提高激光输出特性。

In order to improve the output characteristics of Nd：YVO4/Cr4＋：YAG passively Q-switched laser pumped by CW LD, theoretical and experimental investigation were carried out. In comparison with Nd：YAG crystal, Nd：YVO4 crystal has a fairly large emission cross section,so it is advantageous in CW laser. But for certain pump power, energy storage of active material is low, so it is disadvantageous in passively Q-switched laser. On the basis of pas-sive Q-switching rate equation,the influence of beam section of saturable absorber on output characteristics of passively Q-switched laser was investigatedand, a new laser resonator configuration was introduced. The main idea of this new method is to place a suitable beam expander in the typical passively Q-switched laser resonator. A beam expander placed in passively Q-switched laser resonator can increase photon density in saturable absorber,so Q-switch laser out-put characteristics could be raised. With the use of a beam expander of which expanding rate is three,the peak power of Nd：YVO4/Cr4＋：YAG passively Q-switched laser pulse was improved more than one order of magnitude and pulse energy more than twice. The method can be easily used not only on Nd：YVO4/Cr4＋：YAG passively Q-switched la-ser,but also on other passively Q-switched laser in order to improve output characteristics.