
184 Optical Fiber Communication Systems with MATLAB
®
and Simulink
®
Models
5.3 Introduction to Optical External Modulation
The modulation of light waves via an external optical modulator can be classied into
t
hree
t
ypes
d
epending
o
n
t
he
s
pecial
e
ffects
t
hat
a
lter
t
he
p
roperty
o
f
l
ight
w
aves,
e
spe-
cially
t
he
i
ntensity
o
r
t
he
p
hase
o
f
t
he
l
ight
w
ave
c
arrier.
I
n
a
n
ex
ternal
m
odulator,
t
he
i
ntensity
i
s
n
ormally
m
anipulated
b
y
m
anipulating
t
he
p
hase
o
f
t
he
c
arrier
l
ight
w
aves
g
uided
i
n
o
ne
p
ath
o
f
a
n
i
nterferometer.
Ma
ch–Zehnder
i
nterferometric
s
tructure
i
s
t
he
most common type [6,22–25]. See also Appendix 1 for some details of electrode arrange- ...