Geometric phase optical elements based on structured anisotropy are widely used for phase shaping via their orientational degree of freedom. To date, amplitude shaping via space-variant retardance is much less investigated, a practical reason being that the spin-orbit interaction of light couples retardance with the dynamic part of the optical phase. Inspired by the complementary diffractive elements associated with Babinet’s principle, a bilayered subwavelength grating design is proposed in order to cancel out the spatial modulation of the dynamic phase usually associated with space-variant birefringent phase retardation. This concept is illustrated in the framework of single-mode Laguerre–Gauss beam shaping.

中文翻译：

---

巴比涅双层几何相位光学元件

基于结构各向异性的几何相位光学元件通过其定向自由度被广泛用于相位整形。迄今为止，通过空间变化延迟进行幅度整形的研究还很少，实际原因是光的自旋轨道相互作用将延迟与光学相的动态部分耦合在一起。受与巴比涅原理相关的互补衍射元件的启发，提出了一种双层亚波长光栅设计，目的是消除通常与时变双折射相位延迟有关的动态相位的空间调制。在单模Laguerre-Gauss波束成形框架中对此概念进行了说明。