Independent phase modulation for quadruplex polarization channels enabled by chirality-assisted geometric-phase metasurfaces

Robust and dynamically polarization-controlled tunable plasmon induced transparency (PIT) resonance in designed finite-array nanostructures metasurface is demonstrated, where sharp resonance is guaranteed by design and protected against large geometrical imperfections even for micro-zone sub-array. By employing the explicit analysis of near-field characteristic in the reciprocal-space based on the momentum matching, and the far-field radiation features with point-scattering approach in real-space sparked from Huygens’s principles, the physics of interference resonance for plane-wave optical transmission and reflection of the metasurface is theoretically and thoroughly investigated. The distinctive polarization-selective and Q-tunable PIT shows robust features to performance degradations in traditional PIT system caused by inadvertent fabrication flaws or geometry asymmetry-variations, which paves way for the development of reconfigurable and flexible metasurface and, additionally, opens new avenues in robust and multifunctional controllable nanophotonics device design and applications.

Section: Discussionmentioning

confidence: 94%

Robust tunable plasmon induced transparency in coupled-resonance finite array of metasurface nanostructure

Liu

2021

“…Metasurfaces control the amplitude, phase, and polarization of local fields by manipulating the shape, geometry, and arrangement of the sub-wavelength polarizable inclusions embedded in a host medium 43 , 44 . The interaction between the incident EM beam and the metasurface absorber can be explained by the induced currents generated from the excited electric and magnetic dipole moments on the unit-cells.…”

Section: Analysis and Designmentioning

confidence: 99%

“…www.nature.com/scientificreports/ Metasurface absorber structure. Artificially engineered metasurfaces find extreme applications in radio, microwave and optical frequency regions as diverse as metalenses, high-gain antennas, energy harvesters, transmit/reflectarrays, absorbers, to name a few [41][42][43][44] . The basic structure of metasurface absorber consists of an array of unit-cells replicated a number of times in the x and y directions.…”

Section: Analysis and Designmentioning

confidence: 99%

An ultra-thin double-functional metasurface patch antenna for UHF RFID applications

Koohestani

Ghaneizadeh

2021

An ultra-thin double-functional metasurface patch antenna (MPA) was proposed, where it can operate not only in the antenna mode but also can simultaneously act as perfect absorber for normal incident waves, suitable for RFID applications in the 868 MHz band. The MPA structure consists of a typical coaxially-fed patch antenna merged, for the first time, with a metasurface absorber acting as artificial ground. A methodology for the unit-cell design of the metasurface is proposed followed by an equivalent circuit model analysis, which makes it possible to transform a low-loss ($$tan\delta =0.0015$$ t a n δ = 0.0015 ) unit-cell with highly-reflective characteristics to a perfect absorber for normal incident waves. It is based on modifying the critical external coupling by properly introducing slits on the unit-cell, allowing to design an ultra-thin ($$\lambda _0/225$$ λ 0 / 225 at 868 MHz) and a very compact structure in comparison to previously developed designs. For validation purposes, the MPA was fabricated and its performances in both functional modes were characterized numerically and experimentally. It is demonstrated that merging the absorber with the patch not only allows obtaining a well-matched ($$|S_{11}|<-30$$ | S 11 | < - 30 dB) antenna with an enhanced gain (by 175.6% compared to a typical patch) at the desired frequency but also leads to an overall thickness of only 2.5 mm ($$\lambda _0/138.1$$ λ 0 / 138.1 at 868 MHz). With an absorber size limited to the MPA dimensions, a reasonable 1.3 dB reduction in powers reflected by the MPA was achieved compared to a similar size metallic sheet. Whilst having the lowest profile among the so far reported RFID readers, the proposed MPA can be conveniently fitted for example within the required volume of smart shelf RFID readers or used in portable RFID readers while being capable of mitigating multipath reflection issues and incorrect reading of RFID.

“…These conventional methods are realized by bulky structures because long distance is needed for phase accumulation. Recently, a lot of investigations have been carried out to design compact and low profile polarization converters for integration and miniaturization purposes 5 – 7 . Metasurfaces which are 2-D arrays of scattering particles are good candidates for design of thin polarization converters 8 .…”

Section: Introductionmentioning

confidence: 99%

Tunable broadband polarization converters based on coded graphene metasurfaces

Khajeh

Hamzavi-Zarghani

Yahaghi

et al. 2021

In this paper, two optimization algorithms (randomly initialized hill climbing and genetic algorithms) are considered to design broadband polarization converters based on coded metasurfaces. A pixeled graphene patch with an elliptic structure is proposed for the initial solution. Each pixel can be 1 and 0 which represents the presence and absence of the graphene. The initial guess tends to the optimum configuration after several optimization processes. Four broadband polarization converters are designed utilizing the optimization algorithms. By changing the chemical potential of graphene, the operation frequency of the polarization converters can be adjusted. Furthermore, the effects of relaxation time of graphene and incident angle on the polarization conversion bandwidth of the four designed structures are investigated.