Large area metasurface lenses in the NIR region

Abstract

Metasurfaces have revolutionized the definition of compact optics. Using subwavelength periodic structures of nanostructured dielectrics, the refractive index and absorption properties of metasurfaceswhich are 2D metamaterialscan manipulate light to a degree not possible with conventional bulk glasses and crystals. The phase, polarization, spin (for circularly polarized light), amplitude and wavelength of light can all be manipulated and crafted to user-specified values to mimic the action of a lens, which we refer to as a metalens (ML). MLs have four major advantages over traditional refractive lensessuperior resolution, lighter weight, miniaturization and cost. Many metasurfaces with useful functionalities have been proposed in recent years, yet although novel in their approach have few real-world applications. One such market is the use within infrared laser systems, such as laser designators. In this work, we demonstrate metasurface lenses working at a wavelength of λ = 1064 nm, with aperture d = 1 mm and four different Fnumbers (focal length f = 0.5, 1, 2 and 5 mm). The lenses are composed of 700nm high a-Si pillarsranging from 70-360 nm diameterwhich are fabricated using electron beam lithography (EBL) and reactive ion etching processes, on top of a fused silica substrate. Such lenses are shown to have diffraction-limited performance, with focal spot-size agreeing with theoretical values of λ‧f/d. Furthermore, we have designed large area lenses with aperture d = 10 mm, where the number of pillars per lens exceeds 550 million. By using an efficient Python script, we are able to produce these 100 mm 2 samples with just 14 hours of EBL writing time.

Planar metasurface-based concentrators for solar energy harvest: from theory to engineering

“…Kenney et al demonstrated meta-lenses that operated at 1064 nm, with a 1 mm aperture and four different FLs (0.5 mm, 1.0 mm, 2.0 mm, and 5.0 mm). The meta-lenses were composed of a-Si pillars with a height of 700 nm with a diameter ranging from 70 nm to 360 nm, which were fabricated using electron-beam lithography (EBL) and reactive ion etching (RIE), on top of a fused-silica (SiO 2 ) substrate [194]. The focusing efficiency of the fabricated meta-lens was measured up to 67%.…”

Smart Surface Radio Environments

“…Smart Surface Radio Environments -28/42 ing of the structure geometries [181,183]. However, these require many more steps to fabricate and strongly depend on getting the correct aspect ratio of height vs width.…”