Shan Xin, Li Zile, Deng Liangui, Dai Qi
Opt Lett. 2020 Apr 1;45(7):1902-1905. doi: 10.1364/OL.387665.
Metasurfaces, acting as arrays of perfect nano-polarizers, provide a promising approach to manipulate the amplitude of an incident light at the sub-wavelength scale. In this Letter, we design and demonstrate continuous amplitude-modulated meta-fork gratings to generate optical vortex beams. More importantly, benefiting from the unique negative amplitude modulation, the unavoidable zero-order light that conventional amplitude-only elements always suffer disappears by carefully adjusting the orientation of each nanobrick. The dramatically dropped zero-order light with only 3% leakage energy verifies our design. With the advantages of continuous amplitude modulation, zero-order extinction, and super-high resolution, the proposed meta-fork grating will have a widespread application in integrated optical vortex manipulation and promote the emergence of many other amplitude-modulated nano-optical devices.
超表面作为完美纳米偏振器阵列，为在亚波长尺度上操纵入射光的振幅提供了一种很有前景的方法。在本信函中，我们设计并展示了连续振幅调制的元叉光栅以产生光学涡旋光束。更重要的是，受益于独特的负振幅调制，通过仔细调整每个纳米砖的取向，传统仅振幅元件总是会遇到的不可避免的零级光消失了。仅3%泄漏能量的大幅下降的零级光验证了我们的设计。凭借连续振幅调制、零级消光和超高分辨率的优点，所提出的元叉光栅将在集成光学涡旋操纵中得到广泛应用，并推动许多其他振幅调制纳米光学器件的出现。
