Numerical modeling of nanophotonic crystal waveguides and waveguide devices

The objective of this thesis is to construct numerical models for various characteristics of nanophotonic crystals (PCs) waveguide based on its geometrical variation and surface perturbation. The first major work of this thesis is to improve the coupling efficiency to the narrow single mode PC waveg...

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Main Author: Khoo, Eng Huat
Other Authors: Li Jing
Format: Theses and Dissertations
Language:English
Published: 2010
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Online Access:https://hdl.handle.net/10356/41850
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-418502023-07-04T16:12:54Z Numerical modeling of nanophotonic crystal waveguides and waveguide devices Khoo, Eng Huat Li Jing Liu Aiqun School of Electrical and Electronic Engineering DRNTU::Engineering::Electrical and electronic engineering::Nanoelectronics The objective of this thesis is to construct numerical models for various characteristics of nanophotonic crystals (PCs) waveguide based on its geometrical variation and surface perturbation. The first major work of this thesis is to improve the coupling efficiency to the narrow single mode PC waveguide (PCWG) by using PC tapered waveguide (PCTW). The tapered curvature is designed to have either linear or nonuniform shape. The curvature of the PCTW is varied by a parameter, alpha. For alpha > 1 (and alpha < 1), concave (and convex) PCTW is solved respectively whereas alpha = 1 gives the linear structure. A numerical model based on the modified step-theory is developed to calculate the transmission efficiency of the various PCTW curvatures. This numerical model is computationally efficiency and sophisticated enough to include the essential field physics for the simulation of field propagation in PCTW. The numerical results show that an average coupling efficiency of greater than 97 % at alpha = 0.5 is obtained for a short taper length of 36a, where a is the lattice constant. The coupling efficiency is higher and the shorter length is much shorter compared to the previous PCTW designs. The coupling mechanisms and loss characteristics in various tapered curvatures are also discussed. To have an in-depth understanding of the coupling mechanism and the behavior of the interaction between the modes in the tapering section, a set of coupling equations is derived from the Maxwell's equation based on the step theory. The newly developed theory, called the exact step-coupling-theory can describe the coupling mechanism and modal interaction behavior between the propagating modes occurred in waveguide structures with geometrical variation. The exact step-coupling-theory is better than the modified step-theory and other previous semi-analytical model because it allows flexibility in the mode characterization as well as in-depth understanding of the modal behavior in the tapering section. The coupling equations are analyzed in detail to obtain a comprehensive knowledge of the mode coupling and interaction behavior in the tapering section. DOCTOR OF PHILOSOPHY (EEE) 2010-08-18T07:38:09Z 2010-08-18T07:38:09Z 2008 2008 Thesis Khoo, E. H. (2008). Numerical modeling of nanophotonic crystal waveguides and waveguide devices. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/41850 10.32657/10356/41850 en 284 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic DRNTU::Engineering::Electrical and electronic engineering::Nanoelectronics
spellingShingle DRNTU::Engineering::Electrical and electronic engineering::Nanoelectronics
Khoo, Eng Huat
Numerical modeling of nanophotonic crystal waveguides and waveguide devices
description The objective of this thesis is to construct numerical models for various characteristics of nanophotonic crystals (PCs) waveguide based on its geometrical variation and surface perturbation. The first major work of this thesis is to improve the coupling efficiency to the narrow single mode PC waveguide (PCWG) by using PC tapered waveguide (PCTW). The tapered curvature is designed to have either linear or nonuniform shape. The curvature of the PCTW is varied by a parameter, alpha. For alpha > 1 (and alpha < 1), concave (and convex) PCTW is solved respectively whereas alpha = 1 gives the linear structure. A numerical model based on the modified step-theory is developed to calculate the transmission efficiency of the various PCTW curvatures. This numerical model is computationally efficiency and sophisticated enough to include the essential field physics for the simulation of field propagation in PCTW. The numerical results show that an average coupling efficiency of greater than 97 % at alpha = 0.5 is obtained for a short taper length of 36a, where a is the lattice constant. The coupling efficiency is higher and the shorter length is much shorter compared to the previous PCTW designs. The coupling mechanisms and loss characteristics in various tapered curvatures are also discussed. To have an in-depth understanding of the coupling mechanism and the behavior of the interaction between the modes in the tapering section, a set of coupling equations is derived from the Maxwell's equation based on the step theory. The newly developed theory, called the exact step-coupling-theory can describe the coupling mechanism and modal interaction behavior between the propagating modes occurred in waveguide structures with geometrical variation. The exact step-coupling-theory is better than the modified step-theory and other previous semi-analytical model because it allows flexibility in the mode characterization as well as in-depth understanding of the modal behavior in the tapering section. The coupling equations are analyzed in detail to obtain a comprehensive knowledge of the mode coupling and interaction behavior in the tapering section.
author2 Li Jing
author_facet Li Jing
Khoo, Eng Huat
format Theses and Dissertations
author Khoo, Eng Huat
author_sort Khoo, Eng Huat
title Numerical modeling of nanophotonic crystal waveguides and waveguide devices
title_short Numerical modeling of nanophotonic crystal waveguides and waveguide devices
title_full Numerical modeling of nanophotonic crystal waveguides and waveguide devices
title_fullStr Numerical modeling of nanophotonic crystal waveguides and waveguide devices
title_full_unstemmed Numerical modeling of nanophotonic crystal waveguides and waveguide devices
title_sort numerical modeling of nanophotonic crystal waveguides and waveguide devices
publishDate 2010
url https://hdl.handle.net/10356/41850
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