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1. Scattering from Dielectric Metasurfaces in Optical and Microwave Ranges

   https://doi.org/10.1109/JPHOT.2019.2908307  

   Jamilan, Saeid; Gandji, Navid Pourramzan; Semouchkin, George; Safari, Fatemeh; Semouchkina, Elena (April 2019, IEEE Photonics Journal)

   Metasurfaces composed of cylindrical dielectric resonators, responding either in optical or microwave ranges, are investigated with the goal of clarifying common features of their electromagnetic responses and their transformations at variations of array lattice constants and resonator heights. It is found that occurrence of dipolar electric resonances in dense metasurfaces is accompanied by full transmission without relation to overlapping of two dipolar resonances. Since electric resonances in dense metasurfaces experience strong coupling, these structures could not be considered as homogenized media of identical meta-atoms. We demonstrate the possibility of scaling metasurfaces, in order to substitute challenging optical experiments by experiments at microwaves. 

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2. Design of Planar Penetrable Metasurfaces on an Irregular Grid Using Point-Dipole Approximation

   Kwon, Do-Hoon (July 2020, International symposium digest antennas and propagation)

   A design technique for free-standing planar metasurfaces comprising an array of subwavelength resonant inclusions on an irregular grid is presented. The local E-field is evaluated as a sum of discrete and continuous contributions from neighboring and far-separated elements, respectively. The dimension of each resonator is determined from the polarizability relation. Free from the limitations associated with unit-cell analysis and design under periodic boundary conditions, the new design technique allows use of irregular grids for functional electromagnetic surfaces. 

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3. Gradient metasurfaces for integrated optics, plasmonics, and optoelectronics

   https://doi.org/10.1063/5.0284959  

   Roueini, Maliheh A; Paiella, Roberto (November 2025, APL Photonics)

   Gradient metasurfaces provide a well-established platform for the wavefront and polarization control of light propagating in free space. More recent studies have also focused on their integration with plasmonic and dielectric waveguides and optoelectronic devices such as light emitters and photodetectors. In this context, metasurfaces can be used to interface guided modes with free-space radiation, for example, to enforce the selective input coupling or detection of light with prescribed characteristics (in terms of direction of propagation, state of polarization, orbital angular momentum, etc.) or to manipulate the properties of the out-coupled or emitted light according to a desired system operation. These functionalities, which normally involve complex combinations of bulky optical elements, have important applications in multiple areas of high technological significance, from optical interconnects to microdisplays and multifunctional image sensors. Here, we provide a tutorial overview of this field of research, including a description of the basic building blocks (meta-atoms) used in integrated gradient metasurfaces, a review of the main capabilities reported to date, and an outlook on future directions of study and technological prospects. 

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4. Time‐Domain Near‐Field Scanning Microscopy of Terahertz Metasurfaces

   https://doi.org/10.1002/adpr.202500268  

   Wei, Ruxue; Petersen, Soren; Zhang, Weili (January 2026, Advanced Photonics Research)

   Metasurfaces have emerged as an ultrathin, versatile method for manipulating terahertz surface plasma waves that are critical for subwavelength optical control but are very challenging to be excited and characterized. This review presents recent advances in terahertz surface plasmon waves, focusing on three functional areas: excitation through resonant coupling, beam shaping through phase gradient design, and complex field encoding using metaholography. To validate and analyze these phenomena, near‐field scanning terahertz microscopy (NSTM) is recently developed as a powerful tool for mapping the field distribution of surface plasmon waves, spin‐ and polarization‐sensitive responses, and vector wavefront structures with subwavelength resolution. Representative metasurfaces architectures are highlighted, including periodic and nonperiodic resonators, dynamic phase modulators, and multiplexed holographic encoders, and summarize how their performance can be directly observed through the NSTM platform. Together, these studies demonstrate the synergy between metasurfaces design and near‐field characterization. The integration of reconfigurable metasurfaces with an advanced near‐field scanning platform will be key to realizing high‐capacity, tunable terahertz photonic devices. 

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5. Graphene metasurfaces for terahertz wavefront shaping and light emission [Invited]

   https://doi.org/10.1364/OME.473110  

   Li, Yuyu; Krisshnamurthi, Mathan Ramaswamy; Luo, Weijun; Swan, Anna K.; Ling, Xi; Paiella, Roberto (January 2022, Optical Materials Express)

   Graphene is a promising materials platform for metasurface flat optics at terahertz wavelengths, with the important advantage of active tunability. Here we review recent work aimed at the development of tunable graphene metasurfaces for THz wavefront shaping (including beam-steering metamirrors and metalenses) and light emission. Various design strategies for the constituent meta-units are presented, ranging from metallic phase-shifting elements combined with a nearby graphene sheet for active tuning to graphene plasmonic resonators providing the required phase control or radiation mechanism. The key challenge in the development of these devices, related to the limited radiative coupling of graphene plasmonic excitations, is discussed in detail together with recently proposed solutions. The resulting metasurface technology can be expected to have a far-reaching impact on a wide range of device applications for THz imaging, sensing, and future wireless communications. 

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