用液晶空间光调制器产生光阱阵列

液晶空间光调制器能够方便地用于制作各种衍射型光学元件, 但液晶空间光调制器存在分辨率有限的缺点, 本文提出了用液晶空间光调制器制作相位型光栅, 产生一维和二维光阱阵列的新方案, 用迭代傅里叶级数算法优化设计光栅的相位分布, 在不改变空间光调制器硬件参数设置的情况下, 充分利用和发掘了空间光调制器的优点, 同时又能较好地回避其所存在的缺陷. 根据现有的空间光调制器的技术参数, 模拟仿真设计光栅, 计算光强分布, 结果表明: 用大失谐、小功率激光照明, 能够产生具有很高峰值光强和光强梯度的光阱阵列, 囚禁冷原子的光学偶极势达到mK量级, 对原子的作用力远大于原子的重力.

Generation of the array of optical traps by liquid crystal spatial light modulator

Liquid crystal spatial light modulator (LC-SLM) can be readily used to fabricate the diffractive optical elements. However, a disadvantage of the finite resolution always exists in LC-SLM. In this paper, a new scheme of fabricating phase grating with LC-SLM is proposed to produce one-dimensional (1D) and two-dimensional (2D) array of optical traps. The advantage of the LC-SLM is fully utilized and the disadvantage is well avoided in our scheme. The phase distribution of the grating is optimized by using iterative Fourier series expansion. The grating is designed by simulation according to the LC-SLM technique parameters, and the corresponding light intensity distribution is calculated. The results show that the array has very high peak value intensity and big gradient of intensity by illuminating the grating with a large detuning and low power laser. The optical dipole potential of trapping cold atoms achieves the order of mK, and the interaction force between atom and optical field is much greater than the atom gravity.