Dielectric metalens for miniaturized imaging systems: progress and challenges

Abstract

Lightweight, miniaturized optical imaging systems are vastly anticipated in these fields of aerospace exploration, industrial vision, consumer electronics, and medical imaging. However, conventional optical techniques are intricate to downscale as refractive lenses mostly rely on phase accumulation. Metalens, composed of subwavelength nanostructures that locally control light waves, offers a disruptive path for small-scale imaging systems. Recent advances in the design and nanofabrication of dielectric metalenses have led to some high-performance practical optical systems. This review outlines the exciting developments in the aforementioned area whilst highlighting the challenges of using dielectric metalenses to replace conventional optics in miniature optical systems. After a brief introduction to the fundamental physics of dielectric metalenses, the progress and challenges in terms of the typical performances are introduced. The supplementary discussion on the common challenges hindering further development is also presented, including the limitations of the conventional design methods, difficulties in scaling up, and device integration. Furthermore, the potential approaches to address the existing challenges are also deliberated.

An Omnidirectional Dual-Functional Metasurface with Ultrathin Thickness

“…Metasurfaces are artificially constructed periodic sub-wavelength microstructures that can achieve a desired dielectric constant and permeability by actively selecting their material, shape, and arrangement so as to effectively manipulate the phase, amplitude, and polarization of electromagnetic waves [ 1 , 2 , 3 , 4 ]. Metasurfaces can precisely tune light–matter interactions at subwavelength scales, effectively excite surface plasmons (SPs), and achieve a variety of novel physical properties such as zero refractive index [ 5 ], negative reflection [ 6 ], super-resolution [ 7 ], and metalens [ 8 , 9 , 10 ]. More recently, many researchers have enabled metamaterials to achieve perfect emission/absorption by properly designing the electrical and magnetic responses, which break the limits of conventional devices and play important roles in the fields of thermal emitters [ 11 ], thermal imaging [ 12 ], energy harvesting [ 13 , 14 ], and gas detection [ 15 ], etc.…”

The design of a beam shaping lens with flat surfaces and ultra-thin thickness to convert a Gaussian beam to a top-hat beam

“…Different from classical lenses, metalens controls light propagation with discontinuous phase changes introduced by artificial subwavelength component structures other than the accumulation of the optical path [9,10]. Therefore, metalens have a great potential for miniaturized optical systems and draws attentions in applications in wearable and portable medical devices [11]. Typical structures adopted for the components of a metalens are nanorodes [12], nanoslits [13], nanoantenas [14] etc.…”

“…Typical structures adopted for the components of a metalens are nanorodes [12], nanoslits [13], nanoantenas [14] etc. These artificial structures introduce abrupt phase changes with the orientations or * lihuiyu@bistu.edu.cn geometrics of the structures [9][10][11][12][13][14]. In the meanwhile, the metalens could be used for conversion of the polarization state and phase distribution simultaneously [15].…”

Correction: Dielectric metalens for miniaturized imaging systems: progress and challenges

“…After the publication of this article 1 , it is brought to our attention that some mathematical expressions contained errors. Details are listed below.…”