光环晶格的产生与传输研究

Study on the generation and propagation of optical ring lattice

理论和实验研究了单环与多环晶格的产生及空间传输特性。数值结果表明,光环晶格初始产生时共轴叠加的拉盖尔高斯涡旋光束拓扑荷之差决定着光强分布中亮暗花瓣状光斑数量;暗环晶格的相位分布存在奇异点,与光强分布中暗花瓣状光斑数量及位置相互对应,亮环晶格相位分布中无奇异点;随传播距离的增加,光环晶格的亮暗花瓣状光斑均远离光束中心,暗环晶格拓扑荷为正值发生顺时针旋转,为负值则发生逆时针旋转,亮环晶格无旋转特性。实验上,利用反射式空间光调制器产生了光环晶格并使用CCD记录保存,探究了光环晶格的光强分布以及空间传输特性。实验结果与理论结果基本符合,该研究成果为光环晶格的冷原子捕获提供了一定的理论与实验依据。

The generation and propagation of single-ring and multi-ring lattices in free space were studied theoretically and experimentally.Through numerical calculation,it is found that topological charge number difference between coaxial superposition Laguerre-Gaussian vortex beams decides bright or dark petaloid spot number in intensity distribution.Singularities exist in phase distribution of dark ring lattice,they are corresponding to the dark petaloid spots in number and position,but none singularity is found in bright ring lattice.During the propagation of optical ring lattice,dark and bright petaloid spots move away from beam center,clockwise rotation can be observed for dark ring lattice when the topological charge number is positive and anticlockwise rotation for dark ring lattice when the topological charge number is negative.No rotation can be observed for bright ring lattice.In experiment,optical ring lattices are generated by reflective-SLM and captured by a CCD camera,with which the optical intensity distribution and propagation property are studied.The research results can provide some theoretical and experimental foundations for the clod atom trapping of optical ring lattice.