Minimalist Mie coefficient model

Rahimzadegan, Aso; Alaee, Rasoul; Rockstuhl, Carsten; Boyd, Robert W.

doi:10.1364/oe.390331

Cited by 18 publications

(25 citation statements)

References 66 publications

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“…For particles without gain, there is an upper limit of unity to the Mie coefficients of the individual resonators, 42 which sets a limit of 2.2 on the effective Mie coefficients of dimers ( Figure 1 c and Supporting Section S4 ). Accordingly, the fundamental limit of optical chirality is 6.6π|ζ( k 0 l /2)| for a metallic dimer and the significantly higher value of 87.12π 2 |ζ( k 0 l /2)| 2 for a dielectric dimer.…”

Section: Nanodimers In the Electric–magnetic Dipole Approximationmentioning

confidence: 99%

Dual Nanoresonators for Ultrasensitive Chiral Detection

et al. 2021

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The discrimination of enantiomers is crucial in biochemistry. However, chiral sensing faces significant limitations due to inherently weak chiroptical signals. Nanophotonics is a promising solution to enhance sensitivity thanks to increased optical chirality maximized by strong electric and magnetic fields. Metallic and dielectric nanoparticles can separately provide electric and magnetic resonances. Here we propose their synergistic combination in hybrid metal–dielectric nanostructures to exploit their dual character for superchiral fields beyond the limits of single particles. For optimal optical chirality, in addition to maximization of the resonance strength, the resonances must spectrally coincide. Simultaneously, their electric and magnetic fields must be parallel and π/2 out of phase and spatially overlap. We demonstrate that the interplay between the strength of the resonances and these optimal conditions constrains the attainable optical chirality in resonant systems. Starting from a simple symmetric nanodimer, we derive closed-form expressions elucidating its fundamental limits of optical chirality. Building on the trade-offs of different classes of dimers, we then suggest an asymmetric dual dimer based on realistic materials. These dual nanoresonators provide strong and decoupled electric and magnetic resonances together with optimal conditions for chiral fields. Finally, we introduce more complex dual building blocks for a metasurface with a record 300-fold enhancement of local optical chirality in nanoscale gaps, enabling circular dichroism enhancement by a factor of 20. By combining analytical insight and practical designs, our results put forward hybrid resonators to increase chiral sensitivity, particularly for small molecular quantities.

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Section: Nanodimers In the Electric–magnetic Dipole Approximationmentioning

confidence: 99%

Dual Nanoresonators for Ultrasensitive Chiral Detection

et al. 2021

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“…To solve the above equation, we exploit the Mie angles to represent any possible Mie coefficients [103] (Appendix H). Here, we only assume nonabsorbing particles represented with a (detuning) magnetic dipole Mie angle θ M1 .…”

Section: Collective Lattice Resonancesmentioning

confidence: 99%

A Comprehensive Multipolar Theory for Periodic Metasurfaces

Rahimzadegan

Karamanos

Alaee

et al. 2022

Advanced Optical Materials

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Optical metasurfaces consist of 2D arrangements of scatterers, and they control the amplitude, phase, and polarization of an incidence field on demand. Optical metasurfaces are the cornerstone for a future generation of flat optical devices in a wide range of applications. The rapid advances in nanofabrication have made the versatile design and analysis of these ultra‐thin surfaces an ever‐growing necessity. However, a comprehensive theory to describe the optical response of periodic metasurfaces in closed‐form and analytical expressions has not been formulated, and prior attempts are frequently approximate. Here, a theory is developed that analytically links the properties of the scatterer, from which a metasurface is made, to its response via the lattice coupling matrix. The scatterers are represented by their polarizability or T matrix. Explicit expressions for the optical response up to octupolar order in both spherical and Cartesian coordinates are provided, for normal or oblique incidence. Several examples demonstrate that the proposed theoretical approach is a powerful tool for exploring the physics of metasurfaces and designing novel flat optics devices. Novel fully‐diffracting metagratings and particle‐independent polarization filters are proposed, and novel insights into bound states in the continuum, collective lattice resonances, and the response of Huygens’ metasurfaces under oblique incidence are provided.

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“…For such particles, the T-matrix is a diagonal matrix and the elements are the well-known Mie coefficients with a minus sign according to the formulation used in Equations ( 21) and ( 22). [106,111] For a cluster of particles with known T-matrices, the incident field at the local coordinate of one particle is given by the global incident field and the scattered field of all other particles. This requires the representation of local coordinates in each other's frame of reference and, hence, the application of the VSH addition theorem.…”

Section: Methodsmentioning

confidence: 99%

Toward Perfect Optical Diffusers: Dielectric Huygens’ Metasurfaces with Critical Positional Disorder

et al. 2021

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Conventional optical diffusers, such as thick volume scatterers (Rayleigh scattering) or microstructured surface scatterers (geometric scattering), lack the potential for on‐chip integration and are thus incompatible with next‐generation photonic devices. Dielectric Huygens’ metasurfaces, on the other hand, consist of 2D arrangements of resonant dielectric nanoparticles and therefore constitute a promising material platform for ultrathin and highly efficient photonic devices. When the nanoparticles are arranged in a random but statistically specific fashion, diffusers with exceptional properties are expected to come within reach. This work explores how dielectric Huygens’ metasurfaces can implement wavelength‐selective diffusers with negligible absorption losses and nearly Lambertian scattering profiles that are largely independent of the angle and polarization of incident waves. The combination of tailored positional disorder with a carefully balanced electric and magnetic response of the nanoparticles is shown to be an integral requirement for the operation as a diffuser. The proposed metasurfaces’ directional scattering performance is characterized both experimentally and numerically, and their usability in wavefront‐shaping applications is highlighted. Since the metasurfaces operate on the principles of Mie scattering and are embedded in a glassy environment, they may easily be incorporated in integrated photonic devices, fiber optics, or mechanically robust augmented reality displays.

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Minimalist Mie coefficient model

Cited by 18 publications

References 66 publications

Dual Nanoresonators for Ultrasensitive Chiral Detection

Dual Nanoresonators for Ultrasensitive Chiral Detection

A Comprehensive Multipolar Theory for Periodic Metasurfaces

Toward Perfect Optical Diffusers: Dielectric Huygens’ Metasurfaces with Critical Positional Disorder

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