Transcript TITLE: Modal analysis of complex dielectric waveguides by rigorous

UW ME MEMS & EE Electromagnetic and Remote Sensing Joint SEMINAR
TITLE: Semiconductor dielectric waveguides, basic theory and design principle
SPEARKER: Hung-Wen Chang and Tuo-Lun Wu
National Sun Yat-Sen University, Institute of Electro-Optical Engr, Kaohsiung , Taiwan
DATE: OCT 14, 3:00PM
PLACE: ME 134
ABSTRACT: Dielectric waveguides are important passive devices in optical communication systems. The dielectric
ridge waveguide is the basic building block for integrated optics. By controlling the shape (width and depth, etc)
of the ridge structure, one can also control the optical field concentration, propagation constant and even the
polarization. Unlike the microwave waveguide, the field distribution is very complex and it is not confined entirely
within the core as in the case of dielectric waveguides. Thus it is very hard to analyze and to design optical circuits.
In this talk we will cover various optical devices made of passive dielectric waveguides such as the loss ARROW
waveguide, Y-branch beam splitter/combiner, directional coupler, polarization converter, polarizer and optical
filters made of arrayed waveguide grating (AWG) and micro-ring cavities.
We will discuss the use of both scalar vectored theory and approximation method for obtaining effective mode
index of the ridged waveguides. Various waveguide design concers including available materials index ranges,
waveguide mode field distribution, mode field confinement (spot size, isolation), mode polarization (critical for
active devices) and waveguide dispersion characteristics will be addressed.
Example includes the complete design of a 64 channel AWG optical mask and optical circuit layout.
MTL
ERSL
UW ME MEMS & EE Electromagnetic and Remote Sensing Joint SEMINAR
TITLE: Modal analysis of complex dielectric waveguides by rigorous transverse mode integral equation formulation
SPEARKER: Hung-Wen Chang and Tuo-Lun Wu
National Sun Yat-Sen University, Institute of Electro-Optical Engr, Kaohsiung , Taiwan
DATE: OCT 13, 2:30PM
PLACE:
EE Room 303
ABSTRACT: Planar light wave circuits (PLC) holds great promise for the future of optical communication systems.
There are many complex integrated photonic waveguide structures that are difficult for commercial software packages
based on BPM, FD-TD and mode-matching method. While no single method will be able to address these problems
independently, the coupled transverse-mode integral-equation method that we have been developing provides reliable
analysis of general rectangular-like dielectric waveguides.
The problem on hand is first separated into (or stair-case approximated by) slices of layered structures. Fields in each
slice can be expanded by both TE to y and TM to y (1-D) layered waveguide modes within that particular slice. The
expansion coefficient vectors are closely related to the y–component electric and magnetic fields on the slice boundaries.
It can be shown these interfacial tangential fields obey a coupled transverse mode integral equation (CTMIE).
These coupled integral equations are then converted into a homogeneous matrix equation via orthogonal projection.
The nontrivial solutions for the matrix equation are used to construct the full-wave modes field distribution as well as
the mode propagation constant for the structure under investigation. Among all the methods mentioned above CTMIE
formulation is the most rigorous and most analytical in nature. Even though the CTMIE formulation is somewhat
complex, it requires the least computational resources. This technique can be extended to study waveguides with more
complex structures and can provide, up to eight accurate digits.
MTL
ERSL