vii
TABLE OF CONTENTS
CHAPTER
TITLE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xi
LIST OF FIGURES
xii
LIST OF SYMBOLS
LIST OF ABBREVIATIONS
1
2
PAGE
xviii
xxi
INTRODUCTION
1
1.1
Background of Research
1
1.2
Problem Statement
3
1.3
Objectives of Research
3
1.4
Scope of Research
4
1.5
Significance of Research
5
1.6
Thesis Arrangement
5
THEORY
8
2.1
Introduction
8
2.2
Erbium-Doped Fiber (EDF)
8
2.2.1
Spontaneous and Stimulated Emission
10
2.2.2
The Quasi Three-Level Energy System
12
viii
2.2.3
17
2.3
Principle of Optical Fiber Laser
18
2.4
Nonlinear Effects
20
2.4.1
Stimulated Brillouin scattering (SBS)
21
2.4.1.1
Brillouin Frequency Shift
23
2.4.1.2
Brillouin Gain Coefficient
25
2.4.1.3
Brillouin Threshold
26
2.4.2
3
Gain Measurement of EDFA
Applications of SBS Process
27
2.5
Narrow Linewidth Fiber Laser
28
26
Summary
30
DESIGNS AND CHARACTERIZATION OF FILTERS
FOR ERBIUM DOPED FIBER LASER
32
3.1
Introduction
32
3.2
Erbium Doped Fiber Lasers (EDFLs)
34
3.3
Designs of Tunable Fiber Laser by Employing
Wavelength Selective Filters
39
3.3.1
Tunable Bandpass Filter (TBF)
40
3.3.1.1
Principle of TBF
40
3.3.1.2
Tunable Fiber Laser Using TBF
42
3.3.2
3.3.3
Arrayed Waveguide Grating (AWG)
47
3.3.2.1
Working Principle of AWG
47
3.3.2.2
Tunable Fiber Laser Using AWG
52
Ultra-Narrow Bandwidth Tunable Filter
(UNB-Tunable Filter)
3.3.3.1
Working Principle of UNBTunable Filter
3.3.3.2
62
Summary of the Tunable Fiber Laser Using
Various Wavelength Selective Elements
3.4
60
Tunable Fiber Laser Using UNBTunable Filter
3.3.4
57
Characterization of UNB-Tunable
Filter
3.3.3.3
57
Summary
68
70
ix
4
SINGLE AND MULTIWAVELENGTH
NARROW LINEWIDTH FIBER LASER
71
4.1
Introduction
71
4.2
Single Longitudinal Mode (SLM) Operation
72
4.2.1
Single Mode EDF Fiber Laser Using UltraNarrow Bandwidth Tunable Filter
4.3
Brillouin Fiber Laser
4.3.1
73
81
Generation of Non-Linear Stimulated
Brillouin Scattering Effect
4.3.1.1
82
Effect of Length and Effective
Area for Stimulated Brillouin
Scattering
4.3.1.2
Stimulated Brillouin Scattering
over Pump Power
4.3.1.3
4.3.2
Cavity Designs of Brillouin Fiber Laser
4.3.3
Ultra-Narrow Linewidth SLM Brillouin
Fiber Laser Using Highly Nonlinear Fiber
Multiwavelength Brillouin Fiber Laser
4.4.1
86
Stimulated Brillouin Scattering in
Dispersion Compensating Fiber
4.4
84
89
92
93
102
Analyses of Multiwavelength Brillouin
Brillouin Fiber Laser Using High
Resolution Optical Spectrum Analyzer
4.4.2
103
Tunable Single Stokes Extraction from
20-GHz Brillouin Fiber Laser Using
UNB-Tunable Filter
4.5
5
Summary
110
120
APPLICATION OF NARROW LINEWIDTH FIBER
LASER FOR RADIO FREQUENCY GENERATION
123
5.1
Introduction
123
5.2
Radio Frequency
123
5.3
Tunable, Narrow Linewidth Fiber Laser
126
x
5.3.1
Closely Spaced Dual-Wavelength ErbiumDoped Fiber Laser
5.3.2
126
Tunable Dual Wavelength Erbium-Doped
Fiber Laser
5.3.3
134
Radio Frequency Spectrum for CloselySpaced Dual Wavelength Erbium-Doped
Fiber Laser
5.4
6
Summary
135
137
CONCLUSION AND RECOMMENDATIONS
139
6.1
Introduction
139
6.2
Recommendations
141
REFERENCES
143
Appendices A-B
162-163
xi
LIST OF TABLES
TABLE NO.
2.1
TITLE
The symbols and their respective denotations of atomic
rate equation
3.1
14
The comparison of characterization of wavelength
selective elements used in fiber laser setup
5.1
PAGE
Radio-frequency spectrum band
68
124
xii
LIST OF FIGURES
FIGURE NO.
2.1
TITLE
PAGE
The basic photon-matter interaction process in twoenergy level system; (a) optical absorption , (b)
spontaneous emission, (c) stimulated emission
2.2
Schematic diagram of molecular energy of quasi
three-level system (E.Desurvire, 1994)
2.3
12
13
The experimental configuration for gain measurement
of EDFA
17
2.4
Input power versus gain of EDFA
18
2.5
Schematic diagram of a basic free-space laser
19
system
2.6
The illustration of SBS effect in optical fiber
3.1
The experiment setup of erbium-doped fiber laser
using standard 3 m EDF
3.2
36
The lasing spectrum of EDFL; (a) without optical
isolator; (b) with optical isolator
3.4
35
Output power versus emission wavelength at
different pump power
3.3
22
36
The efficiencies performance for different output
coupler and pump power
38
3.5
The schematic diagram of tunable bandpass filter
41
3.6
Propagation of optical signal through fabry-Perot
etalon with incident angle of θ
3.7
The configuration of tunable single wavelength fiber
41
xiii
laser experimental setup by using TBF as wavelength
tuning element
3.8
Tunable single wavelength EDFL using TBF with Cband tuning range
3.9
43
44
The OSNR of each lasing wavelength of tunable fiber
laser using TBF
45
3.10
Average output power against lasing wavelengths
46
3.11
The 3 dB bandwidth against wavelengths
46
3.12
Schematic diagram of an AWG (H. Yenghaus, 2010)
48
3.13
The details of second slab (second FPR) (H.
Yenghaus, 2010)
3.14
Experimental setup of tunable fiber laser by using
1x16 AWG as wavelength selective mechanism
3.15
52
Tunability of laser spectrum by using an AWG for 16
tuning wavelengths
3.16
50
53
The values of OSNR of tunable single wavelength
tunable fiber laser incorporating 16 different channel
54
of AWG
3.17
The average output power of tunable fiber laser of 16different channel of AWG
55
3.18
The bandwidth of each lasing wavelength using AWG
56
3.19
Schematic diagram of UNB- tunable filter
58
3.20
Measured center wavelength of output spectrum
corresponding to the changed of the screw graduation
3.21
Measured output spectrum bandwidth corresponding to
the changed of the screw graduation
3.22
59
60
Characterization of UNB-tunable filter (a) bandwidth
tunability from 50 - 850 pm. (b) wavelength tunability
from 1485 nm-1615 nm.
3.23
The setup of tunable single wavelength fiber ring laser
using UNB-tunable filter as selective gain medium
3.24
61
Tunable single wavelength fiber laser using UNBtunable filter in which wavelengths randomly selected
63
xiv
over large spectra
3.25
Optical signal-to-noise ratio (OSNR) variation versus
the tuned of output wavelengths
3.26
64
65
The average output power against the tuned singlewavelengths using UNB-tunable filter
66
3.27
The 3 dB bandwidth against the tuned wavelength
67
4.1
Schematic diagram of the SLM EDF laser
74
4.2
Output spectrum observed from 0.02 nm and 0.16 pm
resolutions OSA
4.3
Obtained spectrum with and without filtering by the
tunable, high resolution optical
4.4
75
76
Single mode output spectrum as taken from high
resolution OSA (0.16 pm resolution) whereby the inset
shows the spectrum with 0.10 nm span
4.5
77
RF spectrum of output laser (a) without UNB-tunable
filter, (b) with UNB-tunable filter
78
4.6
Setup for delayed self-heterodyne method
80
4.7
RF beat spectrum using delayed self-heterodyne
method
4.8
Simple configuration for investigate the SBS in the
fiber
4.9
84
Brillouin Stokes power versus different BP wavelength
at fixed BP power of 12 dBm
4.11
83
The Stokes spectrum produced by using different
SMF’s length
4.10
80
86
The changed of output spectrum of 50 km SMF by
varying the BP power at fixed BP wavelength of 1550
nm.
87
4.12
Stokes power against Brillouin pump
88
4.13
The comparison of Brillouin spectrum using DCF and
50 km SMF
4.14
90
The Brillouin spectrums of DCF by varying the BP
power
90
xv
4.15
The Stokes power against Brillouin pump for
determining the threshold power of SBS using DCF
91
4.16
The Brillouin fiber laser designing in linear cavity
92
4.17
The ring cavity of Brillouin fiber laser
93
4.18
Configuration of the Brillouin fiber ring laser using
HNFL
4.19
95
The output spectrum of Brillouin Stokes (BS) at BP
power of ≈ 26 dBm (after amplification) at BP
wavelength of 1550 nm using OSA with the resolution
of (a) 0.02 nm; (b) 0.16 pm.
4.20
97
The output spectrum of Brillouin Stokes (BS) at BP
power of -13 dBm (before being amplified) and 18
dBm (after being amplified) at BP wavelength of 1550
nm (a) using OSA with the resolution of (a) 0.02 nm;
(b)0.16 pm.
4.21
98
The output spectrum after filtration by Fabry-Perot
Filter (inset: the spectrum of Fabry-Perot Filter).
4.22
99
The linewidth measurement from the self-heterodyne
technique for (a) the BP signal alone (TLS) (b) the
SLM Brillouin output
4.23
Proposed
experimental
101
setup
for
generating
multiwavelength double-spacing Brillouin fiber laser
4.24
103
The schematic diagram of the measurement principle
of the high resolution OSA
105
4.25
Optical spectrum obtained from the OSA1
106
4.26
Optical spectrum obtained from the OSA2
107
4.27
The peak power against wavelength for OSA1 and
OSA2
4.28
The Optical signal to noise ratio against the
wavelength for OSA1 and OSA2
4.29
109
The experimental setup of double frequency spaced
multiwavelength Brillouin fiber laser
4.30
108
Spectrum of BP and backward Brillouin scattering of
111
xvi
double frequency spaced Brillouin Stokes when BP is
7.6 dBm at 1550 nm wavelength using OSA1 and
OSA2
4.31
113
Individual stokes spectrum after filtered by UNBtunable filter with the extraction of (a) the Brillouin
pump; and (b)-(f) the first to fifth-Stokes, respectively
4.32
114
The individual anti-Stokes Brillouin spectrum after
being extracted
116
4.33
The individual odd-Stokes after being extracted
117
4.34
The optical-signal-to-noise-ratio against wavelength
118
4.35
The FWHM against wavelength
119
5.1
Experimental setup tunable dual-wavelength spacing
using tunable filter
128
5.2
The reflection spectrum of FBG
129
5.3
The enlarged FBG’s reflectivity output spectrum
observed from OSA1 and OSA2
5.4
Zoom in views (span 0.05 nm) of oscillation modes of
lasing action of EDF ring laser using OSA2
5.5
133
The zoom in views of output spectrum taken from
OSA 1, giving dual-wavelength spacing of 2.0 pm
5.8
132
Output spectrum taken from OSA2, giving a dual
wavelength closely-spacing
5.7
131
The output spectrum obtained from OSA1 after the
insertion of UNB-tunable filter within the cavity
5.6
130
133
Dual-wavelength fiber laser output with different
spacing output spectrum taken from OSA2, a) giving a
dual wavelength spacing of 30.5 pm with OSNR of 57
dB and 50 dB, b) giving a dual wavelength spacing of
32.5 pm with OSNR of 58 dB and 53 dB, c) giving a
dual wavelength spacing of 58.0 pm with OSNR of 57
dB and 53 dB.
5.9
The RF beat spectrum with respect to each different
wavelength spacing ; (a) at dual-wavelength spacing of
135
xvii
2pm giving the beat frequency of 0.251 GHz; (b) at
dual-wavelength spacing of 2pm, 30.5 pm, 32 pm and
58 pm which is equivalent to the beat frequency of
0.251 GHz, 3.82 GHz, 4.07 GHz and 7.27 GHz,
respectively
136
xviii
LIST OF SYMBOLS
Ʋ
-
Frequency
H
-
Planck’s Constant
E
-
Energy
𝑅13
-
Rate of Pumping From 𝐸1 To 𝐸3
𝑅31
-
Rate of Stimulated Emission from 𝐸3 To 𝐸1
W12
-
Absorption Rates
W21
-
Stimulated Emission Rates
𝐴𝑅21
-
Spontaneous Radiative Decay/Emission Rate from 𝐸2 To 𝐸1
𝐴𝑅31
-
Spontaneous Radiative Decay/Emission Rate from 𝐸3 To 𝐸1
𝐴𝑅32
-
Spontaneous Radiative Decay/Emission Rate from 𝐸3 To 𝐸2
𝐴𝑁𝑅
32
-
Spontaneous Nonradiative Decay/Emission Rate from 𝐸3 To 𝐸2
𝐴𝑁𝑅
21
-
Spontaneous Nonradiative Decay/Emission Rate from 𝐸2 To 𝐸1
𝜌
-
Laser Ion Density
𝛾(𝑣)
-
Lorentzian Gain Coefficient
𝑣0
-
Central Frequency
∆𝑣
-
Emission Linewidth
𝛾𝛽 (𝑣)
-
Gaussian Coefficient
∆𝑣𝑠
-
Lorentzian Shape of Width
𝑁0
-
Steady State Population Different
𝜆
-
Wavelength of the Signal
xix
𝜏𝑠𝑝
-
The Spontaneous Lifetime
𝜆𝑝
-
Pump Wavelength
𝑘𝑠
-
Wave Number for Scatter Wavelength
𝑘𝑝
-
Wave Number for Pump Wavelength
𝑘𝑎
-
Wave Number for Acoustic Wavelength
Tb
-
Phonon Lifetime
Δ𝑣𝐵
-
Full-Width at Half-Maximum
𝑝0
-
Material Density
Lcoh
-
Pump Coherence Length
Lint
-
Interaction Length Of Pump
𝐼𝑠 (0)
-
Intensity of Incident Pump At Z=0
𝐴𝑠
-
The Amplitude
𝜔𝑜
-
Carrier Frequency
∅𝑠
-
The Phase
𝐴𝐿𝑂
-
Amplitude of the CWSignal
𝜔𝐿𝑂
-
Frequency of the CW Signal
∅𝐿𝑂
-
Phase of the CW Signal
Δ𝜐𝑠.ℎ𝑜𝑚
-
The Bandwidth in the Self-Homodyne Technique
F
-
The Finesse of the Ring Cavity
𝛼
-
The Loss Coefficient of the Fiber
S
-
Loss of the Electric Field Experienced at the Splices
𝜏𝑑
-
The Delayed Time
Δ𝜈𝑟𝑒𝑠
-
The Resolution of the Interferometric Method
𝐿𝑑
-
Length of the Delay Fiber
L
-
Thickness of Etalon
xx
𝑑
-
Input Waveguide Separation
𝐷
-
Output Waveguide Separation
𝑣𝑝
-
Spacing between Two Adjacent Brillouin Stokes
𝑣𝐴
-
Acoustic Velocity within the Glass
∆Υstokes
-
The Stokes Linewidth
∆Υpump
-
The Pump Linewidth
xxi
LIST OF ABBREVIATIONS
SMFs
-
Single Mode Fibers
EDFA
-
Erbium-Doped Fiber Amplifier
EDFL
-
Erbium-Doped Fiber Laser
SBS
-
Stimulated Brillouin Scattering
OSNR
-
Optical-Signal-to-Noise Ratio
BFLs
-
Brillouin Fiber Lasers
DCFs
-
Dispersion Compensating Fibers
TBF
-
Tunable-Bandpass Filter
AWG
-
Arrayed Waveguide Grating
UNB
-
Ultra-Narrow Bandwidth
FBG
-
Fiber Bragg Grating
HNLF
-
Highly Nonlinear Fiber
OSA
-
Optical Spectrum Analyzer
Nd
-
Neodymium
Yb
-
Ytterbium
BFA
-
Brillouin Fiber Amplifier
TDFs
-
Thulium Doped Fibers
SOAs
-
Semiconductor Optical Amplifiers
LD
-
Laser Diode
WDM
-
Wavelength Division Multiplexer
xxii
TLS
-
Tunable Laser Source
FWM
-
Four-Wave Mixing
CPM
-
Cross-Phase Modulation
SPM
-
Self-Phase Modulation
SA
-
Saturable Absorber
RFSA
-
Radio Frequency Spectrum Analyzer
FSR
-
Free Spectral Range
AOM
-
Acoustic Optical Modulator
OPM
-
Optical Power Meter
FPR
-
Free Propagation Region
OCS
-
Optical Channel Selector
BER
-
Bit Error Rate
PC
-
Polarization Controller
FWHM
-
Full-Width at Half-Maximum
BP
-
Brillouin Pump
SMSR
-
Side Mode Suppression Ratio
RF
-
Radio Frequency
EM
-
Electromagnetic
OFB
-
Optical Feedback
FLP
-
Fiber Loop Mirror
xxiii
LIST OF APPENDICES
APPENDICES
TITLE
PAGE
A
List of Publications with Impact Factor
163
B
List of Paper for Attending Conferences
164