High-performance bifunctional polarization switch chiral metamaterials by inverse design method

Abstract

Multifunctional polarization controlling plays an important role in modern photonics, but their designs toward broad bandwidths and high efficiencies are still rather challenging. Here, by applying the inverse design method of model-based theoretical paradigm, we design cascaded chiral metamaterials for different polarization controls in oppositely propagating directions and demonstrate their broadband and high-efficiency performance theoretically and experimentally. Started with the derivation of scattering matrix towards specified polarization control, a chiral metamaterial is designed as a meta-quarter-wave plate for the forward propagating linearly polarized wave, which converts the x-or y-polarized wave into a nearly perfect left-or right-handed circularly polarized wave; intriguingly, it also serves as a 45°polarization rotator for the backward propagating linearly polarized waves. This bifunctional metamaterial shows a high transmission as well as a broad bandwidth due to the Fabry-Perot-like interference effect. Using the similar approach, an abnormal broadband meta-quarter-wave plate is achieved to convert the forward x-and y-polarized or the backward y-and x-polarized waves into left-and right-handed circularly polarized waves with high transmission efficiencies. The integration of multiple functions in a single structure endows the cascaded chiral metamaterials with great interests for the high-efficiency polarization-controlled applications.npj Computational Materials (2019) 5:93; https://doi.

Photonic and Plasmonic Metasensors

“…[258][259][260] In Figure 5, diagrammatic renderings and SEM images of different types of chiral metamaterials are demonstrated. [261][262][263][264][265][266] Among numerous applications of chiral metamaterials, chiroptical effects have received copious interest recently for designing plasmonic biomolecular sensors. [252,253,[270][271][272][273][274][275] Possessing significant advantages compared to the conventional extinction spectroscopy-based sensing methods, chiral metasensors have been introduced as promising platforms for molecular biosensing purposes.…”

“…h,i) Reproduced with permission. [265] Copyright 2019, Springer Nature. j) Reproduced with permission.…”

Spin‐Encoded Wavelength‐Direction Multitasking Janus Metasurfaces

“…A chiral strategy by involving both in‐plane and out‐of‐plane symmetry breaking was proposed to yield direction‐encoded Janus functionalities and to circumvent the issue of inter‐mode interactions, advancing a significant step over available chirality applications reported only for polarization control in LP state. [ 15,39,40 ]…”

Engineering photonic environments for two-dimensional materials

“…Beyond the coupling in the weak or strong regime, the photonic environments can be engineered to achieve many unique functionalities using metamaterials or metasurfaces that having subwavelength building blocks including metallic, semiconductor, or dielectric metaatoms. The meta-atoms are usually made of plasmonic or dielectric nanoantennas which are deliberately arranged to allow for direct control of the light phase [81,82], amplitude [5,83], and polarizations [84][85][86]. Metamaterials can not only manipulate the light at the far-field region, such as polarization conversion [85], perfect absorption [87], light modulation [88], and bend light direction [89,90], but can also manipulate the EM field at the near-field region [91], electrical and magnetic fields distribution controlment, phase control, etc.…”