masterThesis
Análise de guias de onda ópticos segmentados com sequência quase periódica
Fecha
2018-07-13Registro en:
SEGUNDO, Marcos Túlio Antunes Bezerra. Análise de guias de onda ópticos segmentados com sequência quase periódica. 2018. 63f. Dissertação (Mestrado em Engenharia Elétrica e de Computação) - Centro de Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, 2018.
Autor
Segundo, Marcos Túlio Antunes Bezerra
Resumen
Waveguides with high contrast of refractive indexes between the core and the cladding,
usually present considerable scattering losses in the imperfections of the core walls. A
possible solution to solve this problem can be the stratification of the core, through the
process of segmentation using materials with different refractive indexes. In this work,
the vectorial beam propagation method (VBPM) is applied in the analysis of segmented
waveguides with quasi-periodic sequences. The structure has intercalated refractive indices
along the propagation direction and to obtain a quasi-periodic distribution along the
direction of propagation, the Fibonacci sequence was used. In this case, the non-periodicity
of the sequence was applied in order to reduce scattering losses caused by imperfections in
the walls of the guiding region. Two models of dielectric waveguides were studied. The first
to be analyzed was a rectangular waveguide of pure silicon immersed in a silicon dioxide
substrate. Then, it was analysed a rectangular waveguide of pure silicon with a silicon
dioxide substrate, and an overlay of a photoresist, known as SU-8, was deposited on this
basis. The procedure for analysis is based on the propagation of the transverse modes of the
structure along the guiding region, considering the power variation and the dispersion of
the sequenced guide. The results were obtained using a computational platform with code
written in FORTRAN 2008 in conjunction with the PYTHON programming language.
The results show a good response in the distribution of modes, which results in less power
loss due to imperfections in the sidewalls of the guide core. According to the results, it was
found that the use of the proposed waveguide presents lower insertion losses, decreases
the contrast between the refractive indexes of the core and the cladding and exhibits a
linear dispersion.