管板式电极结构对大功率横流CO_2激光横模的影响

Effect of Tube-Plate Electrodes on Laser Transverse Mode of High Power Transverse-Flow CO_2 Laser

为了研究大功率横流CO_2激光器模式的形成原因及改善途径,理论分析了横流CO_2激光器的管板式电极结构。通过数值求解放电区电势的拉普拉斯方程,得到了电势和电场的空间分布。由场强的分布可以定性地认识放电区电子密度、粒子数密度、光子密度的分布情况,从而定性解释了模式形成的原因和光斑能量分布不均匀的特点。计算结果表明,减小电极距离和增大阴极管径都有助于提高光轴附近场强和均匀性,进而可以提高电子密度,从而达到控制、改善光斑模式的作用。在理论分析的基础上,对激光器的电极和光轴等进行了调整,实测得到了明显改善的光斑模式。

In order to study the formation and improvement of laser modes of high power transverse-flow CO_2 laser, the structure of a tube-plate electrode is analyzed theoretically.A Laplace＇s equation describing the electric potential in the discharge area is numerically solved,and the spatial distributions of the electric potential and field are obtained.Based on the distributions of electric field,the densities of electron,population and photon can be predicted theoretically.These results can be used to analyze the formation reasons of laser modes,as well as to explain the nonuniform characteristic of the laser spot energy.It is also shown by the calculations that with the decreasing of electrodes space and increasing of the tube diameter,the magnitudes and uniformity of electric field near the optic axis are enhanced greatly.As a result,the electron density will be increased and the laser modes can be controlled and improved.Based on the theoretical analysis,laser beam modes are improved through slightly adjusting of the electrodes and the optic axis.