774 research outputs found
Hyperuniform disordered structures for selective solar and solar-thermal absorbers
No full textWe explore the ability of hyperuniform disordered structures to enhance light absorption in thin-film solar cells architectures and perform full electromagnetic wave simulations that unveil light trapping techniques capable to attain large absorption enhancements up 85% over the visible spectrum. We predicate this enhancement to the interplay between two key physical phenomena: ultimate control over the light diffraction via a hyperuniformly-patterned surface layer which results in a highly efficient coupling of light to the quasi-guided modes of the absorbing silicon film and a concomitant minimisation of the reflection losses atop of the solar absorber. Our experimental results further validate this approach, showcasing an impressive 65% enhancement in solar light absorption in a freely suspended 1-μm c-Si membrane across the spectral range from 400 to 1050nm. We also explore applications of hyperuniform disordered architectures to high-efficiency solar-thermal absorbers
Local Self-Uniformity in Photonic Networks
No full textComputer simulationsDataset accompanying article with the same title. | Version:
Light confinement in hyperuniform photonic slabs: High-Q cavities and low-loss waveguides
No full textUsing finite-difference-time-domain and band-structure simulations, we demonstrate efficient confinement of TE-polarized radiation and high-Q optical-cavities and low-loss waveguides in planar hyperuniform-disordered (HUD) architectures based on a design strategy that has potential to be a general purpose platform for optical microcircuits. © OSA 2015
Modelling non-Markovian dynamics in photonic crystals with recurrent neural networks
No full textWe develop a recurrent neural network framework to model the non-Markovian dynamics exhibited by two-level atoms interacting with the radiation reservoir of a photonic crystal. Despite the strong non-Markovianity of the atomic dynamics induced by the rapid spectral variation in photonic density of states of the photonic reservoir, our recurrent neural network approach is able to capture precise details in the atomic evolution, including the fractional steady-state atomic population inversion and spectral splitting of the atomic transition. We demonstrate the robustness of the recurrent neural network setup against reduced data sets and its effectiveness to deal with systems of increased complexity
Quantum memory effects in atomic ensembles coupled to photonic cavities
No full textThis article explores the dynamics of many-body atomic systems symmetrically coupled to Lorentzian photonic cavity systems. Our study reveals interesting dynamical characteristics, including non-zero steady states, super-radiant decay, enhanced energy transfer, and the ability to modulate oscillations in the atomic system by tuning environmental degrees of freedom. We also analyze a configuration consisting of a three-atom chain embedded in a photonic cavity. Similarly, we find a strong enhancement of the energy transfer rate between the two ends of the chain and identified specific initial conditions that lead to significantly reduced dissipation between the two atoms at the end of the chain. Another configuration of interest consists of two symmetrical detuned reservoirs with respect to the atomic system. In the single atom case, we show that it is possible to enhance the decay rate of the system by modulating its reservoir detuning. In contrast, in the many-atom case, this results in dynamics akin to the on-resonant cavity. Finally, we examine the validity of the rotating wave approximation through a direct comparison against the numerically exact hierarchical equations of motion. We find good agreement in the weak coupling regime, while in the intermediate coupling regime, we identify qualitative similarities, but the rotating wave approximation becomes less reliable. In the moderate coupling regime, we find deviations of the steady states due to the formation of mixed photon-atom states
Freeform Phononic Waveguides
No full textWe employ a recently introduced class of artificial structurally-disordered phononic structures that exhibit large and robust elastic frequency band gaps for efficient phonon guiding. Phononic crystals are periodic structures that prohibit the propagation of elastic waves through destructive interference and exhibit large band gaps and ballistic propagation of elastic waves in the permitted frequency ranges. In contrast, random-structured materials do not exhibit band gaps and favour localization or diffusive propagation. Here, we use structures with correlated disorder constructed from the so-called stealthy hyperuniform disordered point patterns, which can smoothly vary from completely random to periodic (full order) by adjusting a single parameter. Such amorphous-like structures exhibit large band gaps (comparable to the periodic ones), both ballistic-like and diffusive propagation of elastic waves, and a large number of localized modes near the band edges. The presence of large elastic band gaps allows the creation of waveguides in hyperuniform materials, and we analyse various waveguide architectures displaying nearly 100% transmission in the GHz regime. Such phononic-circuit architectures are expected to have a direct impact on integrated micro-electro-mechanical filters and modulators for wireless communications and acousto-optical sensing applications
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