Dielectric metasurface based high-efficiency polarization splitters

Guo, Zhongyi; Zhu, Lingling; Shen, Fei; Zhou, Hongping; Gao, Rongke

doi:10.1039/c6ra27741a

Cited by 77 publications

(43 citation statements)

References 34 publications

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“…The common phase shifter elements are dielectric ridge waveguides [59,61,62] and highrefractive-index dielectric scatterers. [63][64][65] The scatterers can be designed to achieve either a polarization-dependent [63,66,67] or a polarization-independent [60,[68][69][70] optical response by changing the cross-section of the structure. The first work on polarization-dependent metalenses based on the propagation phase was reported in ref.…”

Section: Propagation Phasementioning

confidence: 99%

Phase Manipulation of Electromagnetic Waves with Metasurfaces and Its Applications in Nanophotonics

Chen

Zhang

et al. 2018

Advanced Optical Materials

126

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elements. Thus, realizing phase manipulation of EM waves at the nanoscale has become a key pursuit for the development of modern optics and nanophotonics.Metamaterials are 3D artificial nanostructures composed of periodic subwavelength unit cells that resonantly couple to the incident EM waves, exhibiting effective electric and magnetic responses not found in nature. [1][2][3] However, these promising potential applications are hindered in their applications due to the challenges of fabricating the required complex 3D nanostructures and the inherent metallic losses and strong dispersion of plasmonic elements at optical frequencies. Planar metamaterials, or so-called metasurfaces, can be fabricated using existing technologies, such as the lithography method and have attracted increasing attention due to their feasibility, low loss, and ease of fabrication. [4,5] The most prominent advantage of metasurfaces is that they can generate spatial phase discontinuities over the full 2π range with an optically thin interface; moreover, the resolution is less than one wavelength. Thus, wavefronts can be shaped with a distance of much less than the wavelength. With the increasing development of metasurfaces, the aforementioned limitations can be solved using various ultrathin optical devices, which have properties superior to their conventional counterparts. [6][7][8][9][10][11][12] Here, we concentrate on the new capabilities of metasurfaces in recent years in manipulating the phase and propagation behaviors of EM waves. In Section 2, we briefly introduce the underlying mechanisms of three types of phase discontinuities. In Section 3, we review the basic applications of phase modulation using metasurfaces. In Section 4, we review more complex and advanced information photonics that have emerged from metasurfaces. In the last section, we provide concluding remarks and an outlook on future development directions. Three Basic Types of Phase Discontinuities Generated by Metasurfaces Resonance PhaseThe pioneering approach to achieve phase discontinuities was to use the dispersion of various metallic nanoantennas, as shown in the left panel of Figure 1a. The optical energy is coupled to surface EM waves propagating back and forth along the antenna surface. Due to the localized surface plasmon resonance, these waves are accompanied by oscillating free electrons Relative to conventional phase-modulation optical elements, metasurfaces (i.e., 2D versions of metamaterials) have shown novel optical phenomena and promising functionalities with more compact platforms and more straightforward fabrication processes. With the ability to generate a spatial phase variation, optical wavefronts can be manipulated into arbitrary shapes at will, enabling new phenomena and integrated ultrathin optical devices to be explored. This review is focused on recent developments regarding phase manipulation of electromagnetic waves with metasurfaces. Starting from their underlying physics for realizing full 2π phase manipulation, an overview of the applica...

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Section: Propagation Phasementioning

confidence: 99%

Phase Manipulation of Electromagnetic Waves with Metasurfaces and Its Applications in Nanophotonics

Chen

Zhang

et al. 2018

Advanced Optical Materials

126

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“…For a long time, the ability to manipulate the flow of electromagnetic wave (EM wave) at will has fascinated scientists and engineers. The emerging metasurfaces which are ultrathin 2D arrangements composed of carefully designed subwavelength resonators, have been widely explored to direct electromagnetic waves in the desired manner, such as anomalous reflection or negative refraction, beam splitting, polarization control, and cloaking . Specifically, a phase‐gradient metasurface has been widely used as a ubiquitous tool to control the reflection and transmission of a known incidence wave .…”

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confidence: 99%

Angular‐Adaptive Spin‐Locked Retroreflector Based on Reconfigurable Magnetic Metagrating

Jing

Lin

et al. 2019

Advanced Optical Materials

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control, [6,[16][17][18] and cloaking. [19][20][21][22] Specifically, a phase-gradient metasurface has been widely used as a ubiquitous tool to control the reflection and transmission of a known incidence wave. [18,[23][24][25][26][27] The majority of these metasurfaces have been based on the generalized laws of reflection and refraction [26] which provide the gradient surface impedance so that the impinging wave acquires the tangential momentum necessary to be locally rerouted toward the desired direction.One fascinating wavefront control for EM wave is retroreflection that is defined as the reflection of the EM wave propagating back along its incident direction. It is very important for compact optical path setup to achieve ultraflat retroreflector in laser fabrication. Heretofore, a conventional cat's-eye retroreflector is composed of a focusing lens and a concave mirror, which behaves like a cat's-eye device in optics. [28,29] Figure 1a shows this conventional conceptual design schematics for achieving retroreflection. This volumetric retroreflector is bulky and not planar, thus not natively compatible for integration and miniaturization. Shortly afterward, utilizing phase-gradient metasurface, low-weight planar ultrathin retroreflector can be implemented. However, as illuminated in Figure 1b, the tangential momenta added by the gradient metasurface have negligible dependence on the incident angle. [11] As a consequence, the gradient metasurface reflects photons back at a particular incident angle, but Retroreflectors made of gradient metasurfaces have recently attracted intense interests due to their ability in reflecting incident light back to its source. So far, the current retroreflectors can only flip the transverse momenta of incident photons in specific incidence angles and thus have limitations in wide-angle applications. Here, a switchable metagrating based retroreflector is proposed for high-efficient spin-locked retroreflection and suppression of undesired diffractions. Upon reflection, the handedness of the waves is kept the same as the incidence. Furthermore, by mechanically altering the folding state of the reconfigurable retroreflector, adaptive tangential momenta could be imparted to the incidence photons, providing a high-performance retroreflection over a continuous range of incidence angles from 27.3° to 52.5°. As a proof of concept, a magnetic metagrating based retroreflector is fabricated at microwave frequencies and experimental measurements show consistent behaviors at various incidence angles. The proposed retroreflector is compact (overall thickness of 0.204 of the wavelength) and inherently insensitive to the illumination angle. As the design concept introduced in the paper could be extended to terahertz and optical frequencies, the design may serve as a promising platform toward reconfigurable spin-based retroreflection devices for not only interface electromagnetics but also ultraflat photonics.For a long time, the ability to manipulate the flow of electromagnetic wave (EM wave) at...

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“…Metasurfaces are artificially designed ultrathin 2D materials composed of subwavelength resonators, which outperforms natural materials with extraordinary electromagnetic properties. Metasurfaces with subwavelength thickness are capable to tailor the wavefront of the electromagnetic (EM) wave, which has led to various intriguing applications, such as beam deflection, beam splitting, flat lens, waveplates, holograms, cloaking, and so forth. Furthermore, metasurface with spin‐based applications has drawn considerable attention due to the cutting‐edge research field of spin optics .…”

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confidence: 99%

0.2 λ₀ Thick Adaptive Retroreflector Made of Spin‐Locked Metasurface

et al. 2018

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The metasurface concept is employed to planarize retroflectors by stacking two metasurfaces with separation that is two orders larger than the wavelength. Here, a retroreflective metasurface using subwavelength-thick reconfigurable C-shaped resonators (RCRs) is reported, which reduces the overall thickness from the previous record of 590 λ down to only 0.2 λ . The geometry of RCRs could be in situ controlled to realize equal amplitude and phase modulation onto transverse magnetic (TM)-polarized and transverse electric (TE)-polarized incidences. With the phase gradient being engineered, an in-plane momentum could be imparted to the incident wave, guaranteeing the spin state of the retro-reflected wave identical to that of the incident light. Such spin-locked metasurface is natively adaptive toward different incident angles to realize retroreflection by mechanically altering the geometry of RCRs. As a proof of concept, an ultrathin retroreflective metasurface is validated at 15 GHz, under various illumination angles at 10°, 12°, 15°, and 20°. Such adaptive spin-locked metasurface could find promising applications in spin-based optical devices, communication systems, remote sensing, RCS enhancement, and so on.

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Dielectric metasurface based high-efficiency polarization splitters

Abstract: In this paper, a novel polarization splitter has been designed based on the dielectric metasurface consisted of silicon nanobricks array, which can generate two different wavefronts for two orthogonal input polarizations with over 90% transmitted efficiency.

Cited by 77 publications

References 34 publications

Phase Manipulation of Electromagnetic Waves with Metasurfaces and Its Applications in Nanophotonics

Phase Manipulation of Electromagnetic Waves with Metasurfaces and Its Applications in Nanophotonics

Angular‐Adaptive Spin‐Locked Retroreflector Based on Reconfigurable Magnetic Metagrating

0.2 λ₀ Thick Adaptive Retroreflector Made of Spin‐Locked Metasurface

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Dielectric metasurface based high-efficiency polarization splitters

Abstract: In this paper, a novel polarization splitter has been designed based on the dielectric metasurface consisted of silicon nanobricks array, which can generate two different wavefronts for two orthogonal input polarizations with over 90% transmitted efficiency.

Cited by 77 publications

References 34 publications

Phase Manipulation of Electromagnetic Waves with Metasurfaces and Its Applications in Nanophotonics

Phase Manipulation of Electromagnetic Waves with Metasurfaces and Its Applications in Nanophotonics

Angular‐Adaptive Spin‐Locked Retroreflector Based on Reconfigurable Magnetic Metagrating

0.2 λ0 Thick Adaptive Retroreflector Made of Spin‐Locked Metasurface

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Product

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0.2 λ₀ Thick Adaptive Retroreflector Made of Spin‐Locked Metasurface