Materiais inovadores em fotônica

Abstract

Science follows several paths, one of them being the discovery of new characteristics in materials. Depending on the paths taken, it is possible to achieve new materials with truly innovative characteristics. We address two types of innovative materials in this thesis. Both are innovative materials in photonics. After an introduction to materials with innovations arising from the manipulation of a common characteristic, the refractive index, we started to verify the behavior of photonic crystals. In literature, the spatial factor is the principal point of the periodicity of optical characteristics in the constituent materials of photonic crystals. However, if the periodic variation occurs temporally, specific phenomena arise as a consequence. One such feature is the appearance of a wave reflected in space after an abrupt (temporal) change in a photonic material. We show that one can expect this behavior when an electromagnetic wave propagates inside material and, suddenly, its electrical permittivity changes value. We also show that if such a change is periodic, we form so-called temporal photonic crystals. Such crystals have a characteristic similar to the spatial case: bands of propagation prohibited inside the material. However, unlike space photonic crystals with propagation prohibited frequency ranges, temporal photonic crystals have propagation prohibited wave vector intervals. The second innovative material in photonics that we deal with in this thesis is one whose design incorporates the so-called PT-symmetry (spatial and temporal inversion symmetry). We use passive PT-symmetry, where the material is carefully designed with only energy loss. Still, it shows typical features of PT-symmetry. The material used for the layers forming the passive PT symmetry are epsilonnear-zero (ENZ), where the electrical permittivity value is near zero. The consequences of this feature are interesting to increase the intensity of the phenomena studied.