Efficient Vortex Generation in Subwavelength Epsilon-Near-Zero Slabs.
Efficient Vortex Generation in Subwavelength Epsilon-Near-Zero Slabs.
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DOI：
10.1103/physrevlett.118.104301
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发表时间：
2016-10
影响因子：
8.6
通讯作者：
A. Ciattoni;A. Marini;C. Rizza
中科院分区：
文献类型：
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作者：
A. Ciattoni;A. Marini;C. Rizza
我们表明，均匀和各向同性的平板，照射的圆偏振光束没有拓扑电荷，产生的反圆偏振分量的反射场和透射场的顺序2的涡旋，作为旋转不变系统的横向磁和横向电的非对称响应的结果。此外，在ε-近零制度，我们发现，涡的产生是非常有效的亚波长厚板坯的近轴制度。这在物理上源于这样一个事实，即真空傍轴场可以激发ε-近零板内的非傍轴场，因为它在物理上大部分体积上具有缓慢变化的场。我们的理论预测表明，ε-近零介质具有很大的潜力，作为纳米光子元件，用于操纵辐射的角动量，因为它们不需要采用复杂的微米或纳米纤维工艺，甚至可以在非常小的（紫外）波长下工作。
We show that a homogeneous and isotropic slab, illuminated by a circularly polarized beam with no topological charge, produces vortices of order 2 in the opposite circularly polarized components of the reflected and transmitted fields, as a consequence of the transverse magnetic and transverse electric asymmetric response of the rotationally invariant system. In addition, in the epsilon-near-zero regime, we find that vortex generation is remarkably efficient in subwavelength thick slabs up to the paraxial regime. This physically stems from the fact that a vacuum paraxial field can excite a nonparaxial field inside an epsilon-near-zero slab since it hosts slowly varying fields over physically large portions of the bulk. Our theoretical predictions indicate that epsilon-near-zero media hold great potential as nanophotonic elements for manipulating the angular momentum of the radiation, since they are available without resorting to complicated micro- or nanofabrication processes and can operate even at very small (ultraviolet) wavelengths.