高斯激光非准直性对激光会聚铬原子沉积的影响

Effects of Non-Collimation of Gaussian Laser on Laser-Focused Cr Atom Deposition

通过数值计算,仿真研究了高斯激光情况下基片表面不同位置处激光会聚铬原子沉积条纹结构的一致性.研究结果显示高斯激光束构成的光学势阱沿激光中轴线和垂直于激光中轴线两个方向相对于准直高斯激光都有独特的分布结构.这种独特的结构导致铬原子运动轨迹相对于波节位置对称性的破坏,进而导致沉积条纹结构发生变化:在沿激光中轴线方向上,x0从0 mm变化到-50 mm过程中,铬原子的运动轨迹最终的聚集区域相对于波节慢慢失去对称性,并且向x0绝对值较小的一边偏离波节位置;铬原子沉积条纹的半峰全宽、中心峰值和中心线相对于波节的偏移量都随x0的变化而趋向线性变化.其中,半峰全宽约有8 nm的增宽,中心峰值约有50个单位的减少量,中心线相对于波节的偏移量约有15 nm的增大量.

The uniformity of the deposited lines by laser- focusing along the substrate surface is simulated with Gaussian laser. The result shows that the optical potential formed by the Gaussian laser is different from the collimated Gaussian laser either along or perpendicular to the laser axis. This difference results in asymmetry of atomic trajectories related to the laser standing node, and the congregation area is offset to smaller than absolute value of x0 when x0 varies from 0mm to -50mm. Consequently, all the full width at half maximum （FWHM）, center peak and offsets of center of the deposited lines have the linear variations with x0, and each of them has 8nm increase, 50 units decrease and 15nm increase, respectively, when x0 varies from 0mm to -50 mm.