激光功率对铬原子束一维沉积的影响

Effect of Laser Power on One-Dimensional Deposition of Chromium Atomic Beam

以粒子光学方法为基础,利用适当步长的四阶Runge-Kutta算法模拟研究了准直铬原子束经过波长为425.55 nm,功率分别为3.93 mW和40 mW的一维高斯激光驻波场汇聚作用后所沉积的一维条纹情况。在以上两种激光功率下,沉积条纹沿ox方向的结构质量的周期性相同,而沿着oy方向的结构质量却存在很大的差异:在3.93 mW时,每一根沉积条纹在oy方向上都非常清晰,并且半高宽在[-0.5,0.5](以激光束腰半径为单位)的区域内具有较好的一致性,对比度在[-0.2,0.2]区域内有较好一致性;在40 mW时,每一根沉积条纹呈现出较为复杂的结构,在激光束的中轴区域附近[-1.08,1.08]内,原本在3.93 mW时的一根条纹分裂成三根。另外,3.93 mWH寸y=0的平面内条纹情况和40 mW时y=±1.08平面内情况对应性很好,即平均间距为212.78 nm,半高宽为21.65 nm,对比度为24.78。分析结果表明,较好地沉积条纹与适当激光功率有关。

Deposition of collimated chromium （Cr） atomic beam focused by one-dimensional Gaussian standing-laser field with wavelength of 425.55 nm and powers of 3.93 mW and 40 mW is examined from particle-optics approach, using fourth-order Runge-Kutta algorithm with adaptive step size. The results show that the deposited structure has uniform periodicity along ox direction, while the structure quality has much difference along oy direction with different laser powers. When laser power is 3. 93 mW, each nanoline is very clear, and the full width at half maximum （FWHM） is uniform in range of [-0.5, 0.5], where the unit is one laser waist radius, and the contrast is uniform in range of [-0.2, 0.2] along oy direction. When laser power is 40 mW, the nanostructure has three nano lines at the place where only one nanoline for 3.93 mW in range of [-1.08, 1.08] along oy direction. In addition, the structure in the plane of y=0 for 3.93 mW is similar to that in the plane of y=±1.08 for 40 mW, i.e. the average space is 212.78 nm, FWHM is 21.65 nm, and the contrast is 24.78. So the good deposited structure should correspond to suitable laser power.