Singularity in a two-point complex coherence function, known as coherence vortices, represents zero visibility with a helical phase structure. In this paper, we introduce a novel technique to generate the coherence vortices of different topological charges by incoherent source transmittance with exotic structured binary pinholes. The binary pinhole structures have been realized by lithography, followed by wet etching methods. We control the transmittance from the incoherent source plane using these exotic apertures, which finally results in a coherence vortex spectrum that features multiple and pure orbital angular momentum modes. The generation of the coherence vortices is achieved within the two-point complex spatial coherence function. The spatial coherence function exhibits the helical phase profile in its phase part, and its absolute part shows a doughnut-shaped structure. A theoretical basis is developed and validated with simulation, and experimental results. The coherence vortex spectra with OAM modes superposed with opposite topological charges, known as photonic gears, are also generated with the proposed theory.

中文翻译：

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由二元针孔引起的相干涡旋


两点复相干函数中的奇点（称为相干涡旋）表示具有螺旋相结构的零能见度。在本文中，我们介绍了一种新技术，通过具有奇异结构二进制针孔的非相干源透射率来产生不同拓扑电荷的相干涡旋。二元针孔结构已经通过光刻技术实现，然后是湿法蚀刻方法。我们使用这些奇异的孔径来控制来自非相干源平面的透射率，最终产生具有多种纯轨道角动量模式的相干涡旋光谱。相干涡旋的产生是在两点复空间相干函数中实现的。空间相干函数在其相位部分表现出螺旋相位剖面，其绝对部分表现出甜甜圈状结构。通过仿真和实验结果建立并验证了理论基础。该理论还生成了具有 OAM 模式与相反拓扑电荷叠加的相干涡旋谱，称为光子齿轮。