SIMULATION OF LIGHTWAVE PROPAGATION IN PHOTONIC DEVICES
Loading...
Date
2010-06
Authors
MOHD YUSOFF, MOHD HANAPIAH
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
This dissertation focuses on the simulation of lightwave propagation in planar
devices, which include investigation of single mode conditions in rib waveguide,
designs of compact silica polarization rotator and splitters, investigation of multiple
reflections in photonic crystal (PhC) multimode interference couplers and design of
hybrid I-D and 2-D PhC wavelength division multiplexers and channels interleavers.
In the design approach, we have adopted semi-analytical technique which
allows us to incorporate fast optimization process. Global and local simplex search
techniques were extensively used. In the investigation of single mode conditions in
rib waveguide and the design of silica polarization rotator, full vectorial film mode
matching and finite element methods were used. Propagation analysis in the silica
polarization rotator was conducted using finite element eigen-mode expansion
method. The quasi 2-D effective index method with eigen mode expansion method
was used in the design of compact silica grating waveguide polarization splitter,
investigation of multiple reflections in hybrid PhC multi mode interference coupler
and design of hybrid PhC wavelength division multiplexers and channel interleavers.
Basically all the objectives set in the thesis were achieved. In the
investigation of single-mode gallium arsenide/aluminium gallium arsenide
(GaAs/AIGaAs) rib waveguide, single-mode formulation for silicon on silica is
shown to be equally applicable to GaAs/AIGaAs rib waveguide. A direct method of
identifying vertical single-mode cut-off limit is also established by using power
confinement factor in the waveguide. In the design and optimization of polarization
controlling optical components, compact silica polarization rotator and polarization
splitter were investigated. A compact silica polarization rotator of length 790 pm
with slanted sidewall angle of 46° was designed. It has an overall conversion
efficiency of 99%, with very low crosstalk value of -38 dB and a power transfer
efficiency of about 81 %. As for the silica polarization splitter it consisted of a
symmetric three channel directional coupler, with intermediate conventional
waveguide at the center and two grating waveguides on the outside. a compact design
was obtained with an overall length of 340 fJ.m and splitting ratio for the TE and TM
polarized signals obtained at 36 dB and 15 dB respectively.
Finally in this thesis, optical components based on hybrid I-D and 2-D
photonic crystal structure were proposed and investigated. In the investigation of
hybrid photonic crystal multimode interference coupler, the effect of multiple
reflections is observed to be one of the main reasons why image periodicity in the
couple departs from self-imaging principle. And in the proposed wavelength division
multiplexer, an efficient design was proposed for 1.3111.55 pm wavelength, with a
total device length of 12.33 pm. Its power transfer efficiency is 91 % and extinction
ratios of -23.7 dB and -20.8 dB at wavelength l.31 fJ.m and 1.55 fJ.m respectively. For
the channel interleaver, an interaction length of 2800 pm give a channel spacing of
0.8 nm wavelength, with output efficiency of 90%.
Description
Keywords
SIMULATION , DEVICES