双月形圆周阵列超表面生成涡旋光束的研究

Research on the generation of vortex beams by the double-moon-shaped array meta-surface

涡旋光束作为一种近年来新兴的结构化光束,因自身携带轨道角动量的特性,使其在光学微操控、生物医学、光信息传输等领域有着极大的应用前景。在以往生成涡旋光束的报道中,通常存在器件尺寸较大、激发光为圆偏光以及波长单一等问题,本文提出了一种基于双月形金属银单元与二氧化硅基底结合的亚波长尺寸超构表面来实现涡旋光束的生成。此种结构尺寸微小,且可以在偏振方向任意的线偏光入射下,通过调节超表面的双月形金属单元的横向尺寸来实现多种波长的涡旋光束输出。

As a new kind of structured beam in recent years,the vortex beam has great application prospects in optical particle manipulation,bioscience,and optical information transmission because of its orbital angular momentum.In the previous reports on the generation of vortex be ams,there are some problems,such as large device size,circular polarization of excitation light and single wavelength.This paper presents a meta-surface structure for generating a vortex beam.The comb ination of the metal silver unit and the silica substrate enables the output of the vortex beam to ac hieve a highly integrated experimental system.This structure does not dep end on the polarization direction of the excitation light.Compared with other methods that must rely on circular polarization excitation to generate a vortex beam,this structure realizes linear polarizatio n excitation in the simulation and has no special requirements on the polarization direction,which is benefici al to improve system stability and integration.It is also proved by simulation that by changing the lateral dimension of the meta-surface on the meta-surface,the output of the multi-wavelength vortex b eam can be realized separately,which satisfies the researcher′s demand for wavelength diversity.