Near-field imaging of optical nanocavities in hyperuniform disordered materials

Granchi, Nicoletta; Lodde, Matteo; Stokkereit, K.; Spalding, Richard; Veldhoven, P.J. van; Sapienza, Riccardo; Fiore, Andrea; Gurioli, Massimo; Florescu, Marian; Intonti, Francesca

doi:10.1103/physrevb.107.064204

Cited by 12 publications

(6 citation statements)

References 37 publications

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“…Interestingly, the high density of modes typical of random systems prevails after the optimization as can be deduced from the presence of many other less prominent peaks in the emission spectrum. This evidences that the optimization of Q does not occur through the formation of a band gap as it is achieved in other disordered systems. − This is further corroborated by the presence, in the final configuration, of other QNMs in spatial and spectral proximity (see Supplementary Figure S4 and S5) and by the very limited change to the hole statistics (see Supplementary Figure S3). The possibility of achieving a Q / V comparable to photonic-crystal cavities while preserving the high density of modes in a small spatial footprint might pave the way to the engineering of multiple Anderson modes in the same structure once the appropriate constraints are provided.…”

Section: Resultsmentioning

confidence: 64%

“…While enhancements of various orders of magnitude in Q can be achieved through intuitive-based approaches and radiation-limited Q s as high as 9 million have been demonstrated in optimized two-dimensional photonic-crystal cavities, progress in the case of random photonic systems has been more limited . Such an issue has been addressed at the ensemble-average level by introducing short-range correlations, − but the Q s of Anderson-localized modes are only on par with engineered cavities in the case of slow-light photonic-crystal waveguides subjected to minute fabrication disorder . On the other hand, the alternative problem of optimizing the Q of a single localized photonic mode in a random system, i.e., to engineer it, has not been tackled.…”

Section: Introductionmentioning

confidence: 99%

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Q-Factor Optimization of Modes in Ordered and Disordered Photonic Systems Using Non-Hermitian Perturbation Theory

et al. 2023

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The quality factor, Q, of photonic resonators permeates most figures of merit in applications that rely on cavity-enhanced light–matter interaction such as all-optical information processing, high-resolution sensing, or ultralow-threshold lasing. As a consequence, large-scale efforts have been devoted to understanding and efficiently computing and optimizing the Q of optical resonators in the design stage. This has generated large know-how on the relation between physical quantities of the cavity, e.g., Q, and controllable parameters, e.g., hole positions, for engineered cavities in gaped photonic crystals. However, such a correspondence is much less intuitive in the case of modes in disordered photonic media, e.g., Anderson-localized modes. Here, we demonstrate that the theoretical framework of quasinormal modes (QNMs), a non-Hermitian perturbation theory for shifting material boundaries, and a finite-element complex eigensolver provide an ideal toolbox for the automated shape optimization of Q of a single photonic mode in both ordered and disordered environments. We benchmark the non-Hermitian perturbation formula and employ it to optimize the Q-factor of a photonic mode relative to the position of vertically etched holes in a dielectric slab for two different settings: first, for the fundamental mode of L3 cavities with various footprints, demonstrating that the approach simultaneously takes in-plane and out-of-plane losses into account and leads to minor modal structure modifications; and second, for an Anderson-localized mode with an initial Q of 200, which evolves into a completely different mode, displaying a threefold reduction in the mode volume, a different overall spatial location, and, notably, a 3 order of magnitude increase in Q.

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Section: Resultsmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Q-Factor Optimization of Modes in Ordered and Disordered Photonic Systems Using Non-Hermitian Perturbation Theory

et al. 2023

Self Cite

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“…This computational study led to the design and fabrication of disordered cellular solids with the predicted photonic band-gap characteristics for the microwave regime, enabling unprecedented free-form waveguide geometries that are robust to defects not possible with crystalline structures [39]. Afterward, stealthy hyperuniform materials were demonstrated to possess singular wave propagation, transport, and elasticity characteristics, including wave transparency [40][41][42][43][44][45][46][47], tunable localization and diffusive regimes [41,48,49], enhanced absorption of waves [50], enhanced solar cell efficiency [51], phononic properties [52][53][54], Luneberg lenses with reduced backscattering [55], extraordinary phased arrays [56,57], optimal sampling array of three-dimensional (3D) ultrasound imaging [58], high quality factor optical cavity [59], and network materials with nearly optimal effective electrical conductivities and elastic moduli [60]. It has been noted that the novel physical properties of disordered isotropic stealthy hyperuniform materials is due to their hybrid liquid-crystal nature, including the fact that they cannot tolerate arbitrarily large holes in the infinite-volume limit, which is Left: Scattering pattern for a crystal.…”

Section: Introductionmentioning

confidence: 99%

Extraordinary optical and transport properties of disordered stealthy hyperuniform two-phase media

Kim,

Torquato

2024

J. Phys.: Condens. Matter

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Disordered stealthy hyperuniform two-phase media are a special subset of hyperuniform structures with novel physical properties due to their hybrid crystal-liquid nature. We have previously shown that the rapidly converging strong-contrast expansion of a linear fractional form of the effective dynamic dielectric constant εe(k1,ω) [Phys. Rev. X 11, 296 021002 (2021)] leads to accurate approximations for both hyperuniform and nonhyperuniform two-phase composite media when truncated at the two-point level for distinctly different types of microstructural symmetries in three dimensions. In this paper, we further elucidate the extraordinary optical and transport properties of disordered stealthy hyperuniform media. Among other results, we provide detailed proofs that stealthy hyperuniform layered and transversely isotropic media are perfectly transparent (i.e., no Anderson localization, in principle) within finitewavenumber intervals through the third-order terms. Remarkably, these results imply that there can be no Anderson localization within the predicted perfect transparency interval in stealthy hyperuniform layered and transversely isotropic media in practicebecause the localization length (associated with only possibly negligibly small higher-order contributions) should be very large compared to any practically large sample size. We further contrast and compare the extraordinary physical properties ofstealthy hyperuniform two-phase layered, transversely isotropic media, and fully 3D isotropic media to other model nonstealthy microstructures, including their attenuationcharacteristics, as measured by the imaginary part of εe (k1 , ω), and transport properties,as measured by the time-dependent diffusion spreadability S(t). We demonstrate thatthere are cross-property relations between them, namely, we quantify how the imaginaryparts of εe(k1,ω) and the spreadability at long times are positively correlated asthe structures span from nonhyperuniform, nonstealthy hyperuniform, and stealthyhyperuniform media. It will also be useful to establish cross-property relations forstealthy hyperuniform media for other wave phenomena (e.g., elastodynamics) as wellas other transport properties. Cross-property relations are generally useful because theyenable one to estimate one property, given a measurement of another property.

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“…[6] At the basis of the control of the Purcell effect [7] is the comprehension and study of two physical quantities: the Q factor and the modal volume V of the cavity. For these reasons, many successful examples in which the Q factor is controlled and optimized both DOI: 10.1002/qute.202300199 theoretically and experimentally [8][9][10][11][12][13] can be brought up. The concept of modal volume, which is less intuitive than the Q factor since it is a function of the position inside the cavity, has been recently clarified by introducing its unavoidable complex-valued nature based on the non-Hermitianicity of open systems.…”

Section: Introductionmentioning

confidence: 99%

Tailoring Fano Lineshape in Photonic Local Density of States by Losses Engineering

Granchi,

Gurioli

2023

Adv Quantum Tech

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Non‐Hermitian theory in photonics revolutionized the understanding of optical resonators, thanks to the concept of quasi‐normal modes (QNM) and to a deep revision of the Purcell factor expression. Counterintuitive effects followed, such as complex modal volumes and non‐Lorentzian local density of states (LDOS) of QNMs. One of the fascinating aspects of non‐Hermitian theory is the analogy with quantum mechanics for autoionizing electronic levels where the absorption cross'section is characterized by Fano lineshapes, caused by interference between the probability of absorption in the continuum and in the bound states. In photonics Fano lineshapes can arise from QNM normalization through the complex modal volume. The link between Fano lineshapes in photonic LDOS of QNMs and in the case of autoionizing states needs to be clarified. Here, by developing an analytical model based on the role of losses in the QNM normalization, they clarify the meaning of the phase of QNM normalized fields (qFano parameter),linking QNMs normalization to the concept of interference among the resonant and the leaky modes. This inspired the design of photonic crystal (PhC) cavity that exhibits LDOS with Fano character inside the itself, providing a proof of principle on how to mold the radiative lifetime by Purcell effect.

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Near-field imaging of optical nanocavities in hyperuniform disordered materials

Cited by 12 publications

References 37 publications

Q-Factor Optimization of Modes in Ordered and Disordered Photonic Systems Using Non-Hermitian Perturbation Theory

Q-Factor Optimization of Modes in Ordered and Disordered Photonic Systems Using Non-Hermitian Perturbation Theory

Extraordinary optical and transport properties of disordered stealthy hyperuniform two-phase media

Tailoring Fano Lineshape in Photonic Local Density of States by Losses Engineering

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