• Photonics Research
  • Vol. 9, Issue 7, 1310 (2021)
Zarko Sakotic1、*, Alex Krasnok2, Andrea Alú2、3, and Nikolina Jankovic1
Author Affiliations
  • 1BioSense Institute-Research Institute for Information Technologies in Biosystems, University of Novi Sad, Dr Zorana Djindjica 1a, 21101, Novi Sad, Serbia
  • 2Advanced Science Research Center, City University of New York, New York, New York 10031, USA
  • 3Physics Program, Graduate Center, City University of New York, New York, New York 10016, USA
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    DOI: 10.1364/PRJ.424247 Cite this Article Set citation alerts
    Zarko Sakotic, Alex Krasnok, Andrea Alú, Nikolina Jankovic. Topological scattering singularities and embedded eigenstates for polarization control and sensing applications[J]. Photonics Research, 2021, 9(7): 1310 Copy Citation Text show less

    Abstract

    Epsilon-near-zero and epsilon near-pole materials enable reflective systems supporting a class of symmetry-protected and accidental embedded eigenstates (EEs) characterized by a diverging phase resonance. Here we show that pairs of topologically protected scattering singularities necessarily emerge from EEs when a non-Hermitian parameter is introduced, lifting the degeneracy between oppositely charged singularities. The underlying topological charges are characterized by an integer winding number and appear as phase vortices of the complex reflection coefficient. By creating and annihilating them, we show that these singularities obey charge conservation, and provide versatile control of amplitude, phase, and polarization in reflection, with potential applications for polarization control and sensing.
    tanh(jk1zt)=±Z0Z1,

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    ε1=ε0(1+ωp2ω02ω2jγω),

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    d=nλr2=nc2f0εdsin2θ,n=0,1,2,,

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    d=(2n+1)λr4=(2n+1)c4fENZεdsin2θ,n=0,1,2,.

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    q=12πdϕ.

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    (kxk0)2+(kyk0)2=sin2θ={εd(nλ02d)2,k0=2πλ0εd(nλENZ4d)2,k0=2πλENZ.

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    Ji=[abejδi],J0=[rTEarTMbejδi]=[ABejδ0],

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    δr=δ0δi,

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    Zin=Z1tanh(jk1zt),(A1)

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    r=ZinZ0Zin+Z0,(A2)

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    tanh(jk1zt)=±Z0Z1.(A3)

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    tanh(jk2zd)=Z1Z2[Z1tanh(jk1zt)Z0Z0tanh(jk1zt)Z1].(A4)

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    Ei=EV+EH=[abejδi]ej(k0xx+k0zz),(D1)

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    Ji=[abejδi].(D2)

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    Er=[rTErTETMrTMTErTM][abejδi]ej(k0xxk0zz),(D3)

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    Jo=[rTEarTMbejδi]=[|rTE|a|rTM|ejδrbejδi]=[ABejδo],(D4)

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    Zarko Sakotic, Alex Krasnok, Andrea Alú, Nikolina Jankovic. Topological scattering singularities and embedded eigenstates for polarization control and sensing applications[J]. Photonics Research, 2021, 9(7): 1310
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