In this article, we analyze the propagation response of Fibonacci based hypercrystals composed by metallic dielectric multilayered metamaterials. The estructure can be engineered to behave as mirrors or stop band filters and absorbers for visible and infrared radiation. The propagation properties of the proposed hypercrystal can be easily tunned and drastically changed by adjusting their geometrical and optical parameters.
The transmittance, reflectance and absorption of silver nanowires metamaterial embedded into a semiconductor matrix with optical gain are numerically investigated. Metamaterials may suffer from appreciable dissipative losses which are inherent for all plasmonic structures. The losses can significantly be reduced by introducing optical gain in the dielectric matrix by placing atomic or molecular impurities which are pumped by an external light source to create a population inversion. We numerically analyzed the optical properties when the semiconductor host material represents a gain medium. We calculate the transmittance, reflectance and absorption at normal incidence in the visible and near infrared ranges. We observed a peculiar behavior of their optical coefficients that can be explained by observing the field redistribution on the metamaterial.
We propose a strategy to design broadband absorbers. It is based on the apodization of a supercell composed of an array of subwavelength metallic-insulator gratings. The proposed absorber consists of grooves with variable depths in a metallic substrate filled with a dielectric material. It was demonstrated that the apodization procedure plays an important role in the required broadband operation of the proposed absorbers. The proposed absorber presented averaged values of absorption of the order of 94% for wavelengths from 700 to 2300 nm. The spectral response of the absorption coefficient, for a plane wave under normal incidence, has been calculated by using an efficient frequency-domain finite-element method.
The absorption and reflection characteristics of multilayered nanoplasmonic gratings with sub wavelength sizes are analyzed in details by using an efficient finite element method. The multilayered structures are composed by several layers of nanoparticles of metals such as Silver, Gold and Aluminum embedded in dielectric such as amorphous silicon over a metallic substrate. The propagations characteristics for several geometrical configurations are obtained and a broadband reflection or absorption covering the near infrared wavelengths has been observed. The proposed nanoplasmonic structures have a great potential for applications in photovoltaic cells or polarizers by improving their reflection or absorption efficiency. Peaks of reflection or absorption larger than 80% were obtained and their performance over the near infrared can be improved by adequately tuning their geometrical parameters, the refractive index and thickness of the layers as well as the nanoparticles shape and size.
Broadband nanostructured metallic-dielectric absorbers and reflectors are of great interest in integrated optics and they
have a great potential for applications like polarizers or reflectors for nanoantennas applications operating in optical
frequencies, covering the interval of the O-E-S-C-L-U bands. In this work, novel geometric and optical configurations
are numerically analyzed. The absorber or reflected central frequencies of the analyzed devices can be easily tuned over
the entire communications wavelength band by varying their geometrics and optical parameters Peaks of absorption
larger than 80% were obtained in optical wavelengths by using metals like silver and gold in combination with silica