可控双空心光束的理论方案及实验研究

提出了一种利用双周期弧向非满额相位调制的方法产生双空心光束的方案. 当准直氦氖激光通过1.5 mm半径透光孔照射到该相位图样时, 在200 mm成像透镜像空间获得长30 mm, 间距57.6μm, 单管束宽度0.11–0.14 mm的双空心光束. 该方案结构简单, 产生的双空心光束具有较好的可控性, 双光管间距由相位调制因子p决定, 能够实现从双空心光束到单空心光束的双向演化. 对所提出的方案进行了实验研究并得到与理论相符的结果. 利用多种组合方式讨论了将该方案拓展到蓝失谐光学囚禁势阱, 可以实现可控的空心双光阱、四光阱与光学晶格等, 有望在冷原子、冷分子囚禁与操控等领域的实验研究中发挥重要作用.

Theoretical and experimental study of a controllable double-dark-hollow beam

A novel scheme is proposed for a double-dark-hollow beam (DDHB) based on non-full-range phase modulation with double-period. Upon illumination by a collimated He-Ni laser beam shaped by a round hole with a radius of 1.5 mm, the DDHB with an axial length of 30 mm, a width of 0.11–0.14 mm for each dark hollow beam and their separated distance being 57.6 μm is generated in the image space of lens with a focal length of 200 mm. The proposed scheme has the advantages of simple construction and high controllability, and the separated distance between the two light pipes is only dependent on the factor of phase modulation of p. Under the given conditions, a reversible evolution process from a DDHB to a single dark hollow beam (SDHB) can be realized. Experiments for our scheme are performed, results of which are consistent with the theoretical ones. A valuable expansion of the application of DDHB in blue-detuned optical trapping is also discussed. Double and four well hollow optical traps, even the hollow optical lattices can be obtained by using various spatial combinations of our DDHB. The proposed DDHB is expected to play an important role in the study of trapping and manipulation of cold atoms or molecules.