Nonreciprocal optical links based on time-modulated nanoantenna arrays: Full-duplex communication

Salary, Mohammad Mahdi; Jafar‐Zanjani, Samad; Mosallaei, Hossein

doi:10.1103/physrevb.99.045416

Cited by 32 publications

(27 citation statements)

References 90 publications

(118 reference statements)

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“…This creates a new paradigm for designing dynamic metasurfaces with 2π phase span and uniform amplitude. Furthermore, time‐modulated metasurfaces give rise to several exotic space‐time scattering phenomena and can be envisioned for a variety of novel applications such as magnetless nonreciprocal components, Doppler cloaking and illusion, pulse shaping, extreme energy accumulation, and localization of light . Development of all‐dielectric time‐modulated metasurfaces is of particular interest as they can enable directional harmonic generation and manipulation in transmission mode by establishing a Huygens' operation regime, eliminating the bidirectionality of harmonics generated by time‐modulated metasurfaces with single isolated resonances.…”

Section: Introductionmentioning

confidence: 99%

A Dynamically Modulated All‐Dielectric Metasurface Doublet for Directional Harmonic Generation and Manipulation in Transmission

Salary

Farazi

Mosallaei

2019

Advanced Optical Materials

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metasurface to achieve a certain functionality in reflection or transmission mode. Recent years have witnessed the development of phase-gradient metasurfaces with different configurations for a wide range of applications such as beam-steering, focusing, and holography. [1,2] These structures allow for integration of various functionalities into a flat surface thus leading to a dramatic reduction in the footprint of optical systems by replacing conventional bulky optical components.Spatiotemporal control over the phase of transmitted and reflected lights across the 2π span is the key to achieve the desired functionalities. The phase tuning mechanisms of metasurfaces have been mostly based on varying the size of nanoantennas within the resonant scattering regime or rotating half-wave plate elements to imprint a geometric phase shift on the circularly polarized light scattered with the opposite handedness. [3,4] For a nanoantenna supporting a single isolated electric or magnetic resonance, the maximal resonant phase agility is π which hinders full control over the light wavefront without employing a back mirror. Metasurfaces with both electric and magnetic responses can be used to overcome this limitation via spectrally overlapping [5] and interleaving [6] electric and magnetic resonances for operation in transmission and reflection modes, respectively. The spectral overlap of electric and magnetic dipole resonances in a Huygens' metasurface satisfies the first Kerker condition leading to suppressed backward scattering from the elements thus eliminating the reflection and giving rise to maximal transmission with 2π phase agility. Although Huygens' metasurfaces have been constructed using metallic elements in microwave regime, bringing plasmonic Huygens' metasurfaces into optical frequencies is challenging due to their complex geometries and arrangements, and is further hindered by the significant increase in the ohmic loss of plasmonic materials at higher frequencies. [7] All-dielectric metasurfaces consisted of high-index subwavelength elements embedded in a low-index environment can eliminate these limitations in that they can support both electric and magnetic resonances with simple geometries and do not suffer from significant dissipative losses. [8][9][10] Moreover, they are fully compatible with standard In this paper, an electrically tunable all-dielectric metasurface doublet is proposed operating at mid-infrared frequency regime with dynamic 2π phase span in transmission mode. Each layer of the metasurface consists of a periodic array of silicon nanobars configured into p-i-n junctions in which the double carrier injection into the intrinsic region under forward bias allows for tuning of the silicon refractive index. The physical mechanism is based on the spectral overlap of high quality factor guided mode resonances supported by each constituent layer establishing an extreme Huygens' operation regime of nearly reflectionless transmission with steep phase spectrum. The short response time of field-driven car...

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Section: Introductionmentioning

confidence: 99%

A Dynamically Modulated All‐Dielectric Metasurface Doublet for Directional Harmonic Generation and Manipulation in Transmission

Salary

Farazi

Mosallaei

2019

Advanced Optical Materials

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“…The quest for breaking reciprocity is of longstanding interest in EM engineering, and is currently eliciting renewed attention in view of its pivotal role in lifting some fundamental limitations in communication systems as well as energy harvesting and heat management . For instance, in wireless communication systems, a nonreciprocal antenna could radiate a very directive beam without being bound to receiving its reflected echo .…”

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confidence: 99%

“…Other magnetless approaches rely on transistor‐based devices and moving media, but are limited in terms of operating frequency, and are difficult to extend to the optical regime. Time‐varying approaches have emerged as attractive alternatives based on time‐modulated devices, which have smaller size, lower cost, and better integrability. In 2015, Shaltout et al introduced time‐gradient phase discontinuities in time‐varying metasurfaces to control the normal momentum component, thereby breaking the time‐reversal symmetry and Lorentz reciprocity.…”

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confidence: 99%

Breaking Reciprocity with Space‐Time‐Coding Digital Metasurfaces

et al. 2019

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which can manipulate electromagnetic (EM) waves in unconventional ways, and have enabled many exotic physical phenomena and effects, also inspiring novel devices and engineering applications. [1] Their 2D versions, commonly referred to as metasurfaces, are experiencing a strong surge of interest owing to a number of attractive features, including ultrathin thickness, low loss, easy fabrication, and potential conformability. In the wake of the pioneering work by Yu et al. [2] on generalized Snell's laws enabled by imparting an abrupt phase shift, metasurfaces have demonstrated unprecedented capabilities in wavefront engineering, amplitude modulation, and polarization conversion, just to mention a few. [2][3][4][5][6] However, metasurfaces that only impart space-gradient phase discontinuities are inherently constrained by Lorentz reciprocity. This implies, for instance, that the time-reversed version of a reflected wave propagates along the same direction as the original incident wave at the same frequency.The quest for breaking reciprocity is of longstanding interest in EM engineering, and is currently eliciting renewed attention in view of its pivotal role in lifting some fundamental limitations in communication systems as well as energy harvesting and heat management. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] For instance, in wireless communication systems, a nonreciprocal antenna could radiate a very directive beam without being bound to receiving its reflected echo. [20] A common way to attain nonreciprocal effects, especially at microwave frequencies, is to break the time-reversal symmetry by means of biased magnetic materials (e.g., ferrites). These, however, are typically bulky, costly, and difficult to integrate and scale up to optical wavelengths, [10] which motivates the strong interest in magnetless approaches. Some of these are based on nonlinear materials, which are not bound by the reciprocity theorem, but are power-dependent and require sufficiently high signal intensity. [11,12] Other magnetless approaches rely on transistor-based devices [13] and moving media, [14,15] but are limited in terms of operating frequency, and are difficult to extend to the optical regime. Timevarying approaches have emerged as attractive alternatives based on time-modulated devices, [16][17][18][19][20][21][22][23][24] which have smaller size, lower cost, and better integrability. In 2015, Shaltout et al. [19] Metasurfaces are artificially engineered ultrathin structures that can finely tailor and control electromagnetic wavefronts. There is currently a strong interest in exploring their capability to lift some fundamental limitations dictated by Lorentz reciprocity, which have strong implications in communication, heat management, and energy harvesting. Time-varying approaches have emerged as attractive alternatives to conventional schemes relying on magnetic or nonlinear materials, but experimental evidence is currently limited to devices such as circulators and antennas. Here, the recently...

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“…TMMs are in principle 2D metamaterials whose constituent subwavelength building blocks are modulated in time via an external stimulus. These metasurfaces exhibit frequency mixing property and can enable a myriad of novel physical effects [ 49–51 ] such as nonreciprocity, [ 52–62 ] extreme energy accumulation, [ 63 ] wide band impedance matching, [ 64,65 ] camouflaging, [ 66,67 ] generation of dynamic beams, [ 68–70 ] signal amplification, [ 71 ] and pulse shaping. [ 72–74 ] They can also extend the degree of light manipulation through space‐time photonic transitions and local modulation‐induced phase shift.…”

Section: Introductionmentioning

confidence: 99%

“…[ 58,75 ] It has been previously established that the temporal frequency conversion of an optical mode in a spatiotemporally modulated periodic system is accompanied with a correlated change in its spatial frequency which exhibits opposite signs for upward and downward temporal frequency conversion. [ 76,77 ] This phenomenon is referred to as space‐time photonic transition which has been exploited to achieve nonreciprocal responses via transition of guided modes in spatiotemporally modulated waveguides, [ 52 ] leaky‐wave antennas, [ 56,59 ] and metasurfaces. [ 55,58 ] The space‐time transitions of optical modes in TMMs have been recently generalized by introducing a local dispersionless phase shift acquired by light upon undergoing frequency conversion in a TMM that is linearly proportional to the modulation phase delay and harmonic order.…”

Section: Introductionmentioning

confidence: 99%

Topological Space‐Time Photonic Transitions in Angular‐Momentum‐Biased Metasurfaces

Sedeh

Salary

Mosallaei

2020

Advanced Optical Materials

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In this paper, topological space‐time photonic transition of light in angular‐momentum‐biased metasurfaces is established, which yields a superposition of orbital‐angular‐momentum (OAM)‐carrying beams at distinct frequency harmonics upon scattering whose topological charges and frequency shifts are correlated. A reflective dielectric metasurface is considered that consists of silicon nanodisk heterostructures integrated with indium‐tin‐oxide and gate dielectric layers placed on a back mirror forming a dual‐gated field effect modulator. The metasurface is divided into several azimuthal sections wherein the nanodisk heterostructures are interconnected via biasing lines. Addressing each azimuthal section with radio‐frequency biasing signals separately allows for flexible implementation of different spatiotemporal modulation profiles. Active tuning of OAM states with high mode‐purity is demonstrated, which yields minimal cross‐talk between OAM channels in a mode‐multiplexed communication system. Moreover, the role of spatiotemporal modulation profile on the spectral and spatial diversity of OAM states is explored. It is shown that angular‐momentum‐biased metasurfaces allow opportunities for hybridized mode‐division and wavelength‐division multiple access through multiplexing and multicasting across distinct OAM states and wavelengths. The nonreciprocity of topological space‐time photonic transitions across the temporal frequency domain and Hilbert space of OAM states is also investigated giving rise to distinct twisted light channels in up‐ and down‐links.

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Nonreciprocal optical links based on time-modulated nanoantenna arrays: Full-duplex communication

Cited by 32 publications

References 90 publications

A Dynamically Modulated All‐Dielectric Metasurface Doublet for Directional Harmonic Generation and Manipulation in Transmission

A Dynamically Modulated All‐Dielectric Metasurface Doublet for Directional Harmonic Generation and Manipulation in Transmission

Breaking Reciprocity with Space‐Time‐Coding Digital Metasurfaces

Topological Space‐Time Photonic Transitions in Angular‐Momentum‐Biased Metasurfaces

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