Optical Biosensors Based on Photonic Crystals Supporting Bound States in the Continuum

Romano, Silvia; Lamberti, Annalisa; Masullo, Mariorosario; Penzo, Erika; Cabrini, Stefano; Rendina, Ivo; Mocella, Vito

doi:10.3390/ma11040526

Cited by 117 publications

(82 citation statements)

References 44 publications

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“…Indeed, radiated fields with momentum close to the BIC point have a polarization winding in a vortex structure around the BIC core, as also recently experimentally verified [13,14]. A striking feature is that the electromagnetic field of a BIC is characterized by a diverging lifetime, or an infinite radiative Q-factor [3,12], from which light-matter interaction could be highly enhanced [16][17][18][19]. Reciprocity implies that far-field excitation of an ideal (infinite Q-factor) BIC mode is not possible.…”

Section: Introductionmentioning

confidence: 73%

Observation of spin-polarized directive coupling of light at bound states in the continuum

Zito

Romano

Cabrini

et al. 2019

Optica

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Spin-polarized directive coupling of light associated with the photonic quantum spin-Hall effect (QSHE) is a nanoscale phenomenon based on strong spin-orbit interaction that has recently attracted significant attention. Herein, we discuss the experimental manifestation of QSHE intrinsic in the Bloch waves associated with a bound state in the continuum (BIC) of a dielectric photonic crystal metasurface (PhCM). We show numerically that BICs in nanoscale PhCMs have photonic spin angular momentum density transverse to the orbital momentum not only at the interfaces but also inside the confining dielectric medium. Then, we experimentally demonstrate that the fundamental Bloch waves of the BIC mode, macroscopically amplified on resonance, propagate along the symmetry axes of the PhCM obeying spin-momentum locking also at normal incidence, i.e., with no symmetry breaking. This BIC-enhanced spindirective coupling of light may enable versatile implementations of spin-optical structures, paving the way for novel photonic spin multiplatform devices.

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Section: Introductionmentioning

confidence: 73%

Observation of spin-polarized directive coupling of light at bound states in the continuum

Zito

Romano

Cabrini

et al. 2019

Optica

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“…uorescence-based enzyme-linked immunosorbent assay (ELISA), which typically achieves sensitivities of the 3-5 pg/mL [36], yet our label-free and very simple approach is more suited for point-of-care applications. It also represents an improvement by over two orders of magnitude compared to plasmonic nanohole array [16] and is even better than a sandwich assay using metal nanoparticles based on a similar structure [37,38] or based on other dielectric metasurfaces [9,39]. We explain this improvement of performance with the high surface sensitivity, the high values of Q-factor and SNR, together with a sharp Fano resonance, which facilitates easy tracking of the resonance.…”

Section: Nanohole Array For Biosensing Applicationmentioning

confidence: 86%

Dielectric Nanohole Array Metasurface For High-Resolution Near-Field Sensing and Imaging

Conteduca

Barth

Pitruzzello

et al. 2020

Preprint

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Dielectric metasurfaces support resonances that are widely explored both for far-field wavefront shaping and for near-field sensing and imaging. Their design explores the interplay between localised Mie resonances and extended Bragg resonances, with a typical trade-off between Q-factor and light localisation; high Q-factors are desirable for refractive index sensing while localisation is desirable for imaging resolution. Here, we show that a dielectric metasurface consisting of a nanohole array in amorphous silicon provides a favourable trade-off between these requirements. We have designed and realised the metasurface to support two optical modes both with sharp Fano resonances that exhibit relatively high Q factors and strong spatial confinement, thereby concurrently optimizing the device for both imaging and biochemical sensing. For the sensing application, we demonstrate a limit of detection (LOD) as low as 1pg/ml for Immunoglobulin G (IgG); for resonant imaging, we demonstrate a spatial resolution below 1µm and clearly resolve individual E.coli bacteria. The combined low LOD and high spatial resolution opens new opportunities for extending cellular studies into the realm of microbiology, e.g. for studying antimicrobial susceptibility.

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“…The discovery of BICs in optics immediately attracted broad attention (see, e.g., Refs. [4][5][6]) due to high potential in applications in communications [7,8], lasing [9][10][11][12], filtering [13], and sensing [14][15][16]. Recent achievements in the field of BIC are discussed in Refs.…”

Section: Introductionmentioning

confidence: 99%

Multipolar origin of bound states in the continuum

et al. 2019

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Metasurfaces based on resonant subwavelength photonic structures enable novel ways of wavefront control and light focusing, underpinning a new generation of flat-optics devices. Recently emerged all-dielectric metasurfaces exhibit high-quality resonances underpinned by the physics of bound states in the continuum that drives many interesting concepts in photonics. Here we suggest a novel approach to explain the physics of bound photonic states embedded into the radiation continuum. We study dielectric metasurfaces composed of planar periodic arrays of Mie-resonant nanoparticles ("meta-atoms") which support both symmetry protected and accidental bound states in the continuum, and employ the multipole decomposition approach to reveal the physical mechanism of the formation of such nonradiating states in terms of multipolar modes generated by isolated meta-atoms. Based on the symmetry of the vector spherical harmonics, we identify the conditions for the existence of bound states in the continuum originating from the symmetries of both the lattice and the unit cell. Using this formalism we predict that metasurfaces with strongly suppressed spatial dispersion can support the bound states in the continuum with the wavevectors forming a line in the reciprocal space. Our results provide a new way for designing high-quality resonant photonic systems based on the physics of bound states in the continuum.

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Optical Biosensors Based on Photonic Crystals Supporting Bound States in the Continuum

Cited by 117 publications

References 44 publications

Observation of spin-polarized directive coupling of light at bound states in the continuum

Observation of spin-polarized directive coupling of light at bound states in the continuum

Dielectric Nanohole Array Metasurface For High-Resolution Near-Field Sensing and Imaging

Multipolar origin of bound states in the continuum

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