RESUMEN

Microgreens have gained attention for their exceptional culinary characteristics and high nutritional value. The present study focused on a novel approach for investigating the easy extraction of plant samples and the utilization of immersible silicon photonic sensors to determine, on the spot, the nutrient content of microgreens and their optimum time of harvest. For the first time, it was examined how these novel sensors can capture time-shifting spectra caused by the molecules' dynamic adhesion onto the sensor surface. The experiment involved four types of microgreens (three types of basil and broccoli) grown in a do-it-yourself hydroponic installation. The sensors successfully distinguished between different plant types, showcasing their discriminative capabilities. To determine the optimum harvest time, this study compared the sensor data with results obtained through standard analytical methods. Specifically, the total phenolic content and antioxidant activity of two basil varieties were juxtaposed with the sensor data, and this study concluded that the ideal harvest time for basil microgreens was 14 days after planting. This finding highlights the potential of the immersible silicon photonic sensors for potentially replacing time-consuming analytical techniques. By concentrating on obtaining plant extracts, capturing time-shifting spectra, and assessing sensor reusability, this research paves the way for future advancements in urban farming.

Asunto(s)

Brassica , Silicio , Estudios de Factibilidad , Antioxidantes , Nutrientes

RESUMEN

In this Letter, we propose a nonreciprocal heterostructure which combines magnetism and chirality in a simple, easy-to-fabricate design and exhibits at least two orders of magnitude larger magnetochiral dichroism, compared to other proposed metamaterials. This effect stems from the simultaneous lack of time-reversal and space-inversion symmetries and is enhanced by collective slow-photon modes originating from the strong bending of the photonic bands at the Brillouin zone boundaries. We investigate the optical properties of this bianisotropic multilayer heterostructure, consisting of consecutive bilayers of chiral and magnetic materials, embedded in air, and discuss the associated photonic band structure and transmission/absorption spectra obtained by means of full electrodynamic calculations.

RESUMEN

In this Letter we introduce a new class of Fano-resonant all-dielectric metasurfaces for enhanced, high figure of merit magneto-optical response. The metasurfaces are formed by an array of magneto-optical bismuth-substituted yttrium iron garnet nano-disks embedded into a low-index matrix. The strong field enhancement in the magneto-optical disks, which results in over an order of magnitude enhancement of Faraday rotation, is achieved by engineering two (electric and magnetic) resonances. It is shown that while enhancement of rotation also takes place for spectrally detuned resonances, the resonant excitation inevitably results in stronger reflection and low figure of merit of the device. We demonstrate that this can be circumvented by overlapping electric and magnetic resonances of the nanodisks, yielding a sharp electromagnetically induced transparency peak in the transmission spectrum, which is accompanied by gigantic Faraday rotation. Our results show that one can simultaneously obtain a large Faraday rotation enhancement along with almost 100% transmittance in an all-dielectric metasurface as thin as 300 nm. A simple analytical model based on coupled-mode theory is introduced to explain the effects observed in first-principle finite element method simulations.

RESUMEN

Using the rigorous Green's function spectral method, we systematically investigate the scattering resonances of different types of Vogel spiral arrays of point-like scatterers. By computing the distributions of eigenvalues of the Green's matrix and the corresponding eigenvectors, we obtain important physical information on the spatial nature of the optical modes, their lifetimes and spatial patterns, at small computational cost and for large-scale systems. Finally, we show that this method can be extended to the study of three-dimensional Vogel aperiodic metamaterials and aperiodic photonic structures that may exhibit a richer spectrum of localized resonances of direct relevance to the engineering of novel optical light sources and sensing devices.

RESUMEN

We report on the occurrence of strong nonreciprocal magnetochiral dichroism in helical structures of magnetic garnet spheres, which emerges as a result of the simultaneous lack of time-reversal and space-inversion symmetries, by means of rigorous full-electrodynamic calculations using the layer-multiple-scattering method. It is shown that a strong effect appears in flat band regions associated with enhanced natural and magnetic optical activity.