Present day optical integrated circuits contain many continuously
bending waveguides making it important to study EM field profiles of
bending waveguides. The mostly widely used numerical method for
analyzing bending waveguides is the beam propagation method (BPM).
Although it can calculate very fast, BPM results are not accurate enough in
many wide-angle applications due to BPM¡¦s intrinsic paraxial approximation.
Recently, full-wave based finite-difference time-domain technique has
become quite popular and has been used to study many optical devices.
Unfortunately it can not be used to study smoothly bending waveguides due
to huge computational resource requirements needed for these large optical
devices. In the absence of reflection in a bending waveguide, other one
way, wide-angle methods can be applied. In this thesis we propose two
such methods to analyze different kinds of bending waveguides. We use
full eigen-mode expansion technique (FEMET) when reflection is negligible.
In cases where reflection is strong, we propose a cylindrical couple
transverse-mode integral-equation (C-CTMIE) to do the job.
Both FEMET and CTMIE methods are built on complete sets of circular
layered modes of the underlying structure. These modes are not easy to
solve because the standard cylindrical mode solver requires extensive
references to Bessel functions of complex arguments and orders. Here in
this thesis, we proposed to expand cylindrical layered modes from planar
layered modes of an equivalent structure. In essence, we renormalize the
existing planar layered waveguide modes and turn them into desired circular
layered modes. We show that using a matrix eigenvector formulation, this
relatively simple technique is not only quite fast but also produces very
accurate results. Finally using these circular modes various S-bend
waveguides are analyzed. We also present a design to minimize the
radiation loss of a circular waveguide using whisper gallery modes.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0704107-182022 |
| Date | 04 July 2007 |
| Creators | Yang, Yi-cheng |
| Contributors | Hidenori Taga, Hung-wen Chang, Tzyy-sheng Horng, Nai-hsiang Sun |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0704107-182022 |
| Rights | withheld, Copyright information available at source archive |
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