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  • Gender:

    Male

  • Discipline:

    Acoustics. Optics. Condensed Matter Physics

  • Education Level:

    With Certificate of Graduation for Doctorate Study

  • Discipline:

    1 Acoustics;
    1 Optics;
    1 Condensed Matter Physics

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Publications

Current position: English > Research > Publications

Janus Bound States in the Continuum with Asymmetric Topological Charges

  • Time:2025-05-13
  • Hits:

  • Journal:

    Physical Review Letters

  • Abstract:

    We propose a novel topological defect called Janus bound states in the continuum (BICs), featuring asymmetric
    topological charges in upward and downward radiation channels. Our approach involves a photonic crystal slab (PCS)
    that initially exhibits both out-of-plane and in-plane mirror symmetry, and this PCS possesses one BIC at the Γ point
    and two BICs off the Γ point. By introducing certain perturbations that break the out-of-plane mirror symmetry, the
    two off-Γ BICs decompose into four circularly polarized states (C points) with identical topological charges (each with
    half the topological charge of the original BIC) while the at-Γ BIC is preserved. Then, we selectively manipulate the
    four C points associated with the downward radiation channel to converge at the at-Γ BIC, forming a Janus BIC with
    distinct topological charges for upward and downward radiation. By further introducing in-plane mirror symmetry
    perturbation, we can bring two of the C points with the same handedness and identical topological charges for upward
    radiation to merge into the Janus BIC. This process results in a Janus chiral BIC which exhibits large intrinsic chirality
    and an infinite Q factor. Janus BICs can induce distinct Pancharatnam–Berry phase singularities in momentum space for
    different incident channels, providing a new approach to control orbital angular momentum. Janus chiral BICs hold
    promise in enhancing direction-dependent and spin-dependent asymmetric light-matter interaction, opening new
    pathways for improving chirality-dependent operation for on-chip devices.

  • Volume:

    134

  • Issue:

    1

  • Page Number:

    013805

  • Translation or Not:

    no

  • Date of Publication:

    2025-01-10

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