Ultra-thin, entirely flat, Umklapp lenses

Abstract

We design ultra-thin, entirely flat, dielectric lenses using crystal momentum transfer, so-called Umklapp processes, achieving the required wave control for a new mechanism of flat lensing; physically, these lenses take advantage of abrupt changes in the periodicity of a structured line array so there is an overlap between the first Brillouin zone of one medium with the second Brillouin zone of the other. At the interface between regions of different periodicity, surface, array guided, waves hybridise into reversed propagating beams directed into the material exterior to the array. This control, and redirection, of waves then enables the device to operate as a Pendry-Veselago lens that is one unit cell in width, with no need for an explicit negative refractive index. Simulations using an array embedded in a slab of silicon nitride (${\text{Si}}_3{\text{N}}_4$) in air, operating at visible wavelengths between $420-500\text{THz}$ demonstrate the effect.

arXiv comment4 pages, 5 figures. 1 page of supplemental material with 2 additional figures

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Cited by in corpus (3)

• Tailored elastic surface to body wave Umklapp conversion
• Acoustic surface modes on metasurfaces with embedded next-nearest neighbor coupling
• Surface corrugated laminates as elastic grating couplers: splitting of SV- and P-waves by selective diffraction