TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE NO
TITLE PAGE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF FIGURES
xi
LIST OF TABLES
xv
LIST OF SYMBOLS
xvi
INTRODUCTION
1
1.1 Objective of this Project
1
1.2 Scope of this Project
3
1.3 Problem Statement
4
1.4 Project Background
5
vii
2
3
4
1.5 Overview of this Project
8
OPTICAL WAVEGUIDES
9
2.1 Optical Fiber transmission
9
2.1.1 Ray Theory
10
2.1.2 Electromagnetic Mode theory
14
2.1.3 Maxwell Equations
14
2.2 Optical waveguide structure
17
2.3 Polymer Waveguides
19
2.3.1 Material Thermal Propagation
20
ASYMMETRIC Y-JUNCTION POWER
SPLITTER
22
3.1 Integrated Optics
22
3.2 Literature Review
24
3.3 Operational Principle
26
3.3.1 Geometry of Y-junction
31
MODELING AND DESIGN OF
WAVEGUIDE
33
4.1 Numerical methods
33
4.1.1 Finite Difference Method
4.1.1.1 Crank Nicolson Method
4.1.2 Finite Element Method
34
36
37
viii
5
4.2 Heat Transfer Equation
40
4.3 Simulation Guide
42
4.3.1 Setting up the model
42
4.3.2 Options and settings
44
4.3.3 Draw Mode
45
4.3.4 Boundary Mode
46
4.3.5 Sub Domain Mode
48
4.3.6 Mesh Mode
49
RESULTS AND DISCUSSION
51
5.1 Project Methodology
51
5.2 Propagation of light through device
54
5.2.1 Light through parallel arms
54
5.2.2 Light through the S-bends
56
5.3 Electric field generated
58
5.4 Thermal Distribution
62
5.5 Optimum Configuration of Y-junction
66
5.5.1 Mode Conversion factor and
Refractive index
66
5.5.2 Crosstalk and Mode Conversion
Factor
68
5.5.3 Attenuation in S-bend and
Heating power
69
ix
5.5.4 Crosstalk and Heating
Power(Coupling Efficiency)
6
70
FUTURE WORK AND CONCLUSION
71
6.1 Thermal Analysis Model
71
6.2 Thermal Coupling Model
72
6.3 Future Work
73
6.3.1 Variable Optical Attenuator
73
6.3.2 Double Digital Optical Switch
(DDOS)
REFERENCES
75
76
x
LIST OF FIGURES
FIGURE NO.
TITLE
2.1
Cross section of a planar waveguide
2.2
Zigzag ray picture for light waves in planar wave
guiding structure showing radiation mode
2.3
11
12
Vector triangle describing the relationship
between β, k and ҝ
2.5a
10
Zigzag ray picture for light waves in a planar wave
guiding structure showing guided modes
2.4
PAGE NO.
13
Typical dielectric waveguides: a)Strip Loaded
waveguide structure. b) Ridge waveguide structure.
c)Air-clad-rib waveguide structure d) Buried type
waveguide structure .e) Embedded
waveguide structure
3.1
18
All of the light couples with the wider channel and
very less light couples with narrower asymmetric
channel.
3.2
28
An electrode used on channel 1 to change its
refractive index leading to thermo coupling.
29
xi
3.3
The vertical cross section through a DOS
4.1
Finite Difference mesh for modeling of a rib
Waveguide
4.2
35
Modeling of a buried waveguide using a
Finite Element mesh
4.5
34
Locating nodes (a) on centre of a mesh cell, or
(b) on mesh points
4.4
31
37
The buried type waveguide is divided into sub
domain region, which are triangles
38
4.6
Model Navigator showing five tabbed pages
42
4.7
Model Navigator showing application modes
43
4.8
Add/Edit Constant dialog box
44
4.9
Axes/Grid settings
45
4.10
Draw Mode for buried type waveguide structure
46
4.11
Boundary settings
47
4.12
Insulated boundaries and uninsulated
boundary (red)
47
4.13
Sub domain settings
48
4.14
Sub domain settings showing the selected domain
(heater in red)
49
4.15
Mesh mode settings
50
5.1
Flowchart defining the procedural work done in
this project
52
xii
5.2
5.3
5.4a)
The top view of the buried type Y-junction power
splitter (using BPM)
54
Simulation for Y-junction
55
The top view of the S-bend of buried type Yjunction power splitter (using BPM)
56
5.4b)
Simulation for parallel arms.
57
5.5a)
The transverse normalized mode field distribution
5.5b)
of mode0 at Ld =2.5mm,Ld is length of the device
.
Mode1 at Ld=4.5mm,X=10µm
5.5c)
The fundamental exclusively excited in the non
heated arm.
5.6
59
60
61
2D thermal distribution with core dimension
2.5µm× 5µm and H= 2.5µm, at heater temperature
300K using FEMLAB 2.0
5.7a)
Temperature profile plot at z=4mm with fixed
heater distance, H=2.5m.
5.7b)
62
63
Graph plotted shows waveguide temperature versus
boundaries of the core (S-bend at z=4mm) with
fixed heater distance, H=2.5m.
5.8a)
64
Temperature profile plot at the gap between two
parallel arms of the waveguide) with fixed heater
distance, H=2.5m.
65
xiii
5.8b)
Graph plotted shows waveguide temperature versus
boundaries of the core (gap between two parallel
arms of the waveguide) with fixed heater distance
, H=2.5m.
5.9a)
Mode conversion factor And Refractive index
Change
5.9b)
68
Plot showing relation between Attenuation in Sbend And Heating Power
5.9d)
67
Plot showing relationship between Crosstalk and
Mode conversion factor
5.9c)
65
69
Plot showing the relationship between Crosstalk
and Heating Power(Coupling Efficiency)
70
6.1
Top view of DOS with S-bend VOA
74
6.2
Evolution from DOS to DDOS
75
xiv
LIST OF TABLES
TABLE NO.
1.1
TITLE
PAGE NO.
The typical properties of waveguide material
used in integrated optics is mentioned in the
tabulated form.
7
3.1
The coupling ratio related to insertion loss
28
5.1
Opto-thermal parameters for utilized
materials (Data Sheet, Technology Evaluation
Report for Optical Interconnections and
Enabling Technologies)
5.2
53
Numerical values for the design parameters of
designed DOS.
53
xv
LIST OF SYMBOLS
A
-
contact area
C
-
heat capacity
d
-
waveguide arm spacing
K
-
thermal coupling estimation
k
-
thermal conductivity
H
-
distance from heater to waveguide core
h
-
thickness of core arm
L
-
Length of device
η
-
refractive index
Q
-
rate of heat flow
t
-
thickness of the substrate
W
-
Heater width
w
-
Core arm width
β
-
propagation constant
µ
-
relative permittivity
∆
-
temperature ratio difference
Φ
-
change in polarizabilty with temperature
xvi
Θ
-
incident angle
λ
-
wavelength
ρ
-
density capacity
ε
-
relative capacity
γ
-
coefficient of volume expansion
Ld
-
Distance of symmetry in waveguide
xvii