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arXiv · 1610.01466

Efficient vortex generation in sub-wavelength epsilon-near-zero slabs

Alessandro Ciattoni·Andrea Marini·Carlo Rizza
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Abstract

We show that a homogeneous and isotropic slab, illuminated by a circularly polarized beam with no topological charge, produces vortices of order two in the opposite circularly polarized components of the reflected and transmitted fields, as a consequence of the difference between transverse magnetic and transverse electric dynamics. In the epsilon-near-zero regime, we find that vortex generation is remarkably efficient in sub-wavelength 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 portion 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/nano fabrication processes and can operate even at very small (ultraviolet) wavelengths.

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Alessandro Ciattoni, Andrea Marini, Carlo Rizza. 2016-10-05. Efficient vortex generation in sub-wavelength epsilon-near-zero slabs. https://doi.org/10.1103/physrevlett.118.104301

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