A waveguide metasurface based quasi-far-field transverse-electric superlens

Abstract

The imaging capability of conventional lenses is mainly limited by the diffraction of light, and the so-called superlens has been developed allowing the recovery of evanescent waves in the focal plane. However, the remarkable focusing behavior of the superlens is greatly confined in the near-field regime due to the exponential decay of evanescent waves. To tackle this issue, we design a waveguide metasurface-based superlens with an extraordinary quasi-far-field focusing capability beyond the diffraction limit in the present work. Specifically, we analyze the underlying physical mechanism and provide experimental verification of the proposed superlens. The metasurface superlens is formed by an array of gradient nanoslits perforated in a gold slab, and supports transverse-electric (TE) waveguide modes under linearly polarized illumination along the long axis of the slits. Numerical results illustrate that exciting such TE waveguide modes can modulate not only optical phase but also evanescent waves. Consequently, some high-spatial-frequency waves can contribute to the focusing of the superlens, leading to the quasi-far-field super-resolution focusing of light. Under 405 nm illumination and oil immersion, the fabricated superlens shows a focus spot of 98 nm (i.e. λ/4.13) at a focal distance of 1.49 μm (i.e. 3.68λ) using an oil immersion objective, breaking the diffraction limit of λ/2.38 in the quasi-far field regime. The developed metasurface optical superlens with such extraordinary capabilities promises exciting avenues to nanolithography and ultra-small optoelectronic devices.

Large‐Area Low‐Cost Multiscale‐Hierarchical Metasurfaces for Multispectral Compatible Camouflage of Dual‐Band Lasers, Infrared and Microwave

“…As a 2D version of metamaterials, metasurfaces can enable many novel phenomena and applications, such as catenary optics, [ 17–19 ] large field of view imaging, [ 20,21 ] multi‐dimensions meta‐holography, [ 22–24 ] asymmetric photonic spin‐orbit interactions, [ 25,26 ] tunable multifunctional devices, [ 27,28 ] generalized Pancharatnam‐Berry Phase, [ 29,30 ] and many others. [ 31–33 ] The ability of metasurfaces to arbitrarily control the light wavefronts provides a promising platform for multispectral camouflage technology. [ 34,35 ] Applying an infrared shielding layer with microwave‐transparent property on a microwave absorber is a general way to realize microwave‐infrared compatible camouflage.…”

Terahertz technology in intraoperative neurodiagnostics: A review

“…Another approach similar to solid immersion effect is based on dielectric microspheres 94,117−121 . In this approach, a dielectric particle is introduced in the far field of the microscope (i.e., it is handled in front of the focal plane and can be placed either on the surface of an imaged object 117 or in close proximity to it 122 ) in order to transfer near-field information and to magnify certain regions of the object. Such virtual images formed by each microsphere are collected with conventional objective 10 −2 λ 0.24λ lens of the microscope.…”

“…In ref. 122 white light microscope based on microsphere superlenses demonstrated resolution up to . Since this approach is usually used in transmission light it can be a perspective way for improvement of spatial resolution of THz microscopy of histological brain samples.…”

A planar ultraviolet objective lens for optical axis free imaging nanolithography by employing optical negative refraction

“…based on subwavelength structured materials, has facilitated the rapid progress of planar optics. [6][7][8] As a representation of planar optics, the planar focusing lens starts with the perfect lens proposed by Pendry in 2000. 9 By employing a negative refractive index material slab, a two-dimensional object could be imaged with subwavelength resolution in a point-to-point manner.…”