Metasurface Optical Characterization Using Quadriwave Lateral Shearing Interferometry

Abstract

An optical metasurface consists of a dense and usually nonuniform layer of scattering nanostructures behaving as a continuous and extremely thin optical component with predefined phase, transmission and reflection profiles. To date, various sorts of metasurfaces (metallic, dielectric, Huygens-like, Pancharatman-Berry, etc.) have been introduced to design ultrathin lenses, beam deflectors, holograms, or polarizing interfaces. Their actual efficiencies depend on the ability to predict their optical properties and to fabricate nonuniform assemblies of billions of nanoscale structures on macroscopic surfaces. To further help improve the design of metasurfaces, precise and versatile postcharacterization techniques need to be developed. Today, most of the techniques used to characterize metasurfaces rely on light intensity measurements. Here, we demonstrate how quadriwave lateral shearing interferometry (QLSI), a quantitative phase microscopy technique, can achieve full optical characterization of metasurfaces of any kind, as it can probe the local phase imparted by a metasurface with high sensitivity and a spatial resolution that reaches the diffraction limit. As a means to illustrate the versatility of this technique, we present measurements on two types of metasurfaces, namely, Pancharatnam-Berry and effective-refractive-index metasurfaces, and present results on uniform metasurfaces, metalenses, and deflectors.

Local Surface Chemistry Dynamically Monitored by Quantitative Phase Microscopy

“…Instead, the use of common path quantitative techniques such as spatial light interference microscopy, [ 28 ] gradient light interference microscopy, [ 29 ] and wavefront sensing such as Shack‐Hartmann, [ 30 ] coded wavefront sensors, [ 31 ] and quadriwave lateral shearing interferometry, [ 32 ] have recently emerged and are gaining momentum owing to their stability and ease of use. They have already proved their potential with in operando studies on biological systems, [ 23,32–34 ] temperature distribution around plasmonic structures, [ 35–38 ] quality control, [ 39 ] characterization of 2D materials, metamaterials and nanoantennas, [ 38,40–42 ] to cite a few examples. Most of these implementations rely, however, on relatively expensive equipment which are not yet widely available, such as spatial light modulators, or complex phase masks manufactured by lithography.…”

Multiobjective Statistical Learning Optimization of RGB Metalens

“…12 in supplementary information section (see Ref. 97 for more details). The x-z experimental intensity maps are depicted in Figs.…”

Quantitative phase microscopy using quadriwave lateral shearing interferometry (QLSI): principle, terminology, algorithm and grating shadow description

“…(h) Examples transmittance and OT images of micro-and nano-objects acquired by QLSI, namely a living cell, 7 a wavefront distortion created by a local micrometric induced temperature temperature in water, 11 a molybdenum disulfide flake, 13 and gold nanoparticle 14 and a metasurface. 15 QLSI is based on the use of a so-called wavefront analyzer that consists of the association of two simple elements: a regular camera and a 2-dimensional (2D) diffraction grating, separated by a couple of millimers from each other (Fig. 1a).…”

“…Albeit conceived in the 90s, the idea of plugging a QLSI device on a microscope is recent. 7 Figure 1h draws an overview of the main applications of QLSI in optical microscopy, namely cell imaging, 7,17 temperature imaging in nanoplasmonics, 10,11 2D-material imaging, 13 single nanoparticle optical characterization 14,18 and metasurface characterization 15 (Figure 1h). QLSI has the ability to become one day a technique of predilection for quantitative phase imaging applications.…”

“…This tilt can be removed by removing the Zernike moment Z 1 1 of the image. 15 A Matlab package for Zernike moment analysis was developed by Amir Tahmasbi.…”