Observation of bound states in the continuum embedded in symmetry bandgaps

Cerjan, Alexander; Jörg, Christina; Vaidya, Sachin; Augustine, Shyam; Benalcazar, Wladimir A.; Hsu, Chia Wei; Freymann, Georg von; Rechtsman, Mikael C.

doi:10.1126/sciadv.abk1117

Cited by 34 publications

(13 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For a metasurface state to be a symmetry-protected BIC (regardless of whether the state is degenerate), the state must be at the center of the Brillouin zone, k ∥ = Γ , and be even with respect to 180° rotation about the out-of-plane axis ( C 2 ) or be at a momentum-space polarization singularity 57 , 58 . The first requirement can be proven as a consequence of the Bragg-diffraction limit and the degeneracy between s- and p-polarized waves in free space 59 , while the latter requirement stems from the fact that the radiative channels at Γ in free space (or any homogeneous and isotropic environment) are always odd with respect to C 2 . In particular, this latter requirement is especially restrictive for symmetry-guaranteed degenerate states, as even though there are a few different possibilities of the metasurface’s in-plane rotational symmetry that allow for symmetry-guaranteed degeneracies, only the presence of six-fold rotational symmetry ( C 6 ) allows for degenerate pairs that are simultaneously even with respect to C 2 (these states form the E 2 irreducible representation regardless of whether reflection or time-reversal symmetry has been added to the system).…”

Section: Resultsmentioning

confidence: 99%

Realizing symmetry-guaranteed pairs of bound states in the continuum in metasurfaces

2022

Self Cite

View full text Add to dashboard Cite

Bound states in the continuum (BICs) have received significant attention for their ability to enhance light-matter interactions across a wide range of systems, including lasers, sensors, and frequency mixers. However, many applications require degenerate or nearly degenerate high-quality factor (Q) modes, such as spontaneous parametric down conversion, non-linear four-wave mixing, and intra-cavity difference frequency mixing for terahertz generation. Previously, degenerate pairs of bound states in the continuum (BICs) have been created by fine-tuning the structure to engineer the degeneracy, yielding BICs that respond unpredictably to structure imperfections and material variations. Instead, using a group theoretic approach, we present a design paradigm based on six-fold rotational symmetry (C6) for creating degenerate pairs of symmetry-protected BICs, whose frequency splitting and Q-factors can be independently and predictably controlled, yielding a complete design phase space. Using a combination of resonator and lattice deformations in silicon metasurfaces, we experimentally demonstrate the ability to tune mode spacing from 2 nm to 110 nm while simultaneously controlling Q-factor.

show abstract

Section: Resultsmentioning

confidence: 99%

Realizing symmetry-guaranteed pairs of bound states in the continuum in metasurfaces

2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, as the periodicity is in the normal direction, the scintillation light is not expected to be well out-coupled with the radiation channels, because of the k z = 0 requirement of the quasi-BIC (confinement is at the Γ point). A better strategy for realizing BIC enhancement in the structure with cm thickness is exploiting the three-dimensional (3D) nanostructures [46], such as with the woodpile architecture [40] (Figure 7). Although, the fabrication of such structures is more challenging than simple 1D or 2D designs, it has been recently shown that they can provide a good platform for BIC type effects.…”

Section: Discussionmentioning

confidence: 99%

Large-Area Photonic Bound State in the Continuum for Ultraviolet and Deep-Blue Emission for Organic, Inorganic, and Perovskite Scintillators

Kowal

Wong

Birowosuto

2023

IEEE Trans. Nucl. Sci.

View full text Add to dashboard Cite

Optimizing the emission properties of materials in ultraviolet and deep blue (UV-DB) is interesting in development of new scintillator devices for the detection of X-ray, γ-ray and radiation particles as those materials can be strong candidates for high light yield and fast scintillators. While their intrinsic material properties are already well studied, photonic enhancement generated through optical confinement could significantly improve their emission characteristics, however one needs to overcome the problem of relatively low refractive indices contrast resulting in poor confinement of UV-DB light. This motivates the search for resonator structures built from readily accessible materials that can boast strong confinement in this spectral regime. Here, we present such a structure, leveraging bound states in the continuum (BICs) to realize large-area confinement of UV-DB light with ultra-high quality factors up to Q ∼10 7 . These ultra-high Q-factors in turn result in strong enhancements in light emission via the Purcell effect. We demonstrate the operation of such a design by simulating the mode shape, Qfactor and emission behaviour in organic, hybrid perovskite and III-V scintillating materials. By tailoring the structure geometry, it can be robustly tuned to match the emission characteristics of chosen materials. We start with considering ideal infinite structure supporting perfect BIC and we extend our model on finite sized structures and we discuss the limitations associated with the self-absorption and thickness of the structure. Our findings pave the way to cost-effective and efficient designs for scintillators in the UV-DB regime.

show abstract

“…Some new attempts to engineer the radiation environment to achieve so-called lines of BICs have emerged quite recently [14]. But the idea and reported results require very complicated geometries [15], which are challenging to fabricate.…”

Section: Introductionmentioning

confidence: 99%

Quasi-guided modes resulting from the band folding effect in a photonic crystal slab for enhanced interactions of matters with free-space radiations

Sun¹,

Cai²,

Levy³

et al. 2023

Beilstein J. Nanotechnol.

View full text Add to dashboard Cite

We elucidate that guided modes supported by a regular photonic crystal slab structure composed of a square lattice of air holes in a silicon slab will transition into quasi-guided (leaky) modes when the radius of every second column of air holes is changed slightly. This intentional geometric perturbation will lead to a doubling of the period in one direction and the corresponding shrinkage of the first Brillouin zone. Because of the translational symmetry in the k-space, leaky waves inheriting the spatial dispersion of the original guided modes, which do not interact with external radiation, will appear with the dispersion curves above the light cone. Our results show that ultrahigh Q-factor resonances with large operating bandwidth can be achieved. Interestingly, the perturbation in only one direction of the photonic lattice will lead to an in-plane wave number-dependent resonance characteristic in both directions. Our numerical results demonstrate a local enhancement of the electric field magnitude by the order of 102, which is even more significant than those in most plasmonic structures. These quasi-guided modes with superior properties will provide a new platform for efficient light–matter interactions.

show abstract

Observation of bound states in the continuum embedded in symmetry bandgaps

Abstract: Designing the photonic environment yields a mechanism for creating bound states in the continuum over a wide range of angles.

Cited by 34 publications

References 55 publications

Realizing symmetry-guaranteed pairs of bound states in the continuum in metasurfaces

Realizing symmetry-guaranteed pairs of bound states in the continuum in metasurfaces

Large-Area Photonic Bound State in the Continuum for Ultraviolet and Deep-Blue Emission for Organic, Inorganic, and Perovskite Scintillators

Quasi-guided modes resulting from the band folding effect in a photonic crystal slab for enhanced interactions of matters with free-space radiations

Contact Info

Product

Resources

About