Absorção em quasi-cristais fotônicos
After Yablonovitch's pioneering work on Photonic Crystals [1], there was a growing interest in studies on the propagation of electromagnetic waves in periodic multilayers. Mainly because of the possibility of guiding, allowing or prohibiting the propagation of light in certain frequency bands w...
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| Formato: | doctoralThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/44656 |
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| Resumo: | After Yablonovitch's pioneering work on Photonic Crystals [1], there was a growing
interest in studies on the propagation of electromagnetic waves in periodic multilayers.
Mainly because of the possibility of guiding, allowing or prohibiting the propagation
of light in certain frequency bands with the use of band gaps (PBGs). On the other
hand, after Kohmoto's pioneering work [2], the study of photonic quasi-crystals has
received a lot of prominence. The photonic quasi-crystals exhibit long-range order, nontranslational symmetry and a characteristic in the self-similarity optical spectra [3], a
very interesting property in fractal studies. In this doctoral thesis, we will approach a
study on the spectrum of absorption and optical transmission in multilayers, using the
theory of photonic quasi-crystals. The technique that we will use for the calculation
of the optical spectrum will be the technique of the transfer matrix. The photonic
quasi-crystals that we will study will be formed by the sequences of Octonacci and
Dodecanacci. Graphenes are materials that have received a lot of attention for their
optoelectronic properties, even in the absence of a band gap. We intend to use graphene
at the interfaces between the layers to obtain the spectra and compare the results without
graphenes. We will also investigate the e ect of the chemical potential for the control of
band gaps in these structures, as well as the in uence of the oblique incidence. The study
of perfect coherent absorption (ACP) has received a lot of prominence in recent years,
mainly for several technological applications, such as modulators [4], Bragg re ectors [5],
plasmonic structures [6], among others. On the other hand, Hermitian systems, previously present only in quantum mechanics, had their studies expanding to acoustic and electronic
systems. Non-Hermitian systems had their equivalent in optical systems where what we
call the parity-time symmetry (PT symmetry) occurs, where the material's refractive
indices satisfy n(x) = n∗(−x). We calculated the transmission spectrum in a photonic
crystal with PT symmetry, formed by known quasi-periodic sequences: Fibonacci, Thue
Morse and Double Period. In these structures, high transmission peaks arise due to the use of PT symmetry. |
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