arXiv subjects

Diana C. Skigin

Publications and source records attributed to Diana C. Skigin.

6 recordsLinked to original sources

arXiv2021

Photonics of fungal cell wall

The cell wall serves as a mechanical protection for the fungi and controls the traffic of molecules entering the cell. However, the optical role of the cell wall has not been fully investigated. In this work, we use a computational simulation to evaluate the optical response of the fungal cell wall. The main advantage of this approach is that the scattering structure can be introduced within the simulation via transmission electronic microscope (TEM) images of its cross section which in this case correspond to real fungal cell walls. The obtained results indicate that the reflectivity of the fungal cell wall depends on the incident wavelength, and then, it modulates the light that reaches the interior of the cell. This suggests that the light stimulus that reaches the inner part of the cell could depend on the structural characteristics of the cell wall. Additionally, regarding the analysis of color, our finding opens up a new and interesting approach to investigate the ecological role of UV light in relation to fungal organisms and their microhabitat.

physics.bio-ph↗

arXiv2013

A simulation method for determining the optical response of highly complex photonic structures of biological origin

We present a method based on a time domain simulation of wave propagation that allows studying the optical response of a broad range of dielectric photonic structures. This method is particularly suitable for dealing with complex biological structures. One of the main features of the proposed approach is the simple and intuitive way of defining the setup and the photonic structure to be simulated, which can be done by feeding the simulation with a digital image of the structure. We also develop a set of techniques to process the behavior of the evolving waves within the simulation. These techniques include a direction filter, that permits decoupling of waves travelling simultaneously in different directions, a dynamic differential absorber, to cancel the waves reflected at the edges of the simulation space, a multi-frequency excitation scheme based on a filter that allows decoupling waves of different wavelengths travelling simultaneously, and a near-to-far-field approach to evaluate the resulting wavefield outside the simulation domain. We validate the code and, as an example, apply it to the complex structure found in a microorganism called Diachea leucopoda, which exhibits a multicolor iridescent appearance.

physics.comp-ph↗

arXiv2007

Bandwidth control of forbidden transmission gaps in compound structures with subwavelength slits

Phase resonances in transmission compound structures with subwavelength slits produce sharp dips in the transmission response. For all equal slits, the wavelengths of these sharp transmission minima can be varied by changing the width or the length of all the slits. In this paper we show that the width of the dip, i.e., the frequency range of minimum transmittance, can be controlled by making at least one slit different from the rest within a compound unit cell. In particular, we investigate the effect that a change in the dielectric filling, or in the length of a single slit produces in the transmission response. We also analyze the scan angle behavior of these structures by means of band diagrams, and compare them with previous results for all-equal slit structures.

physics.class-ph↗

arXiv2005

Phase resonances in obliquely illuminated compound gratings

The existence of phase resonances in obliquely illuminated, perfectly conducting compound gratings is investigated. The diffraction problem of a p-polarized plane wave impinging on the structure is solved using the modal approach. The results show that even under oblique illumination, where no symmetry is imposed by the incident field, there are resonant wavelengths that are clearly associated with a certain degree of symmetry in the phase distribution of the magnetic field inside the cavities. New configurations of this phase distribution take place, that were not allowed under normal incidence conditions. It was found that the interior field is intensified in the resonances, and the specularly reflected efficiency is maximized. In particular, this efficiency is optimized for Littrow mount.

physics.optics↗

arXiv2004

Eigenmodes of index-modulated layers with lateral PMLs

Maxwell equations are solved in a layer comprising a finite number of homogeneous isotropic dielectric regions ended by anisotropic perfectly matched layers (PMLs). The boundary-value problem is solved and the dispersion relation inside the PML is derived. The general expression of the eigenvalues equation for an arbitrary number of regions in each layer is obtained, and both polarization modes are considered. The modal functions of a single layer ended by PMLs are found, and their orthogonality relation is derived. The present method is useful to simulate scattering problems from dielectric objects as well as propagation in planar slab waveguides. Its potential to deal with more complex problems such as the scattering from an object with arbitrary cross section in open space using the multilayer modal method is briefly discussed.

physics.optics↗

arXiv2004

Shape resonances in nested diffraction gratings

The diffraction problem of a plane wave impinging on a grating formed by nested cavities is solved by means of the modal method, for $s$ and $p$ polarization modes. The cavities are formed by perfectly conducting sheets that describe rectangular profiles. The electromagnetic response of the grating is analyzed, paying particular attention to the generation of resonances within the structure. The dependence of the resonances on the geometrical parameters of the grating is studied, and results of far and near field are shown. The results are checked and compared with those available in the literature for certain limit cases.

physics.optics↗