
169Optical Direct and External Modulation
computation
a
nd
i
t
h
as
v
alue
0
.0000001
b
y
d
efault.
I
n
O
CSS
©
, ODE45 with 1e
−7
accuracy is
a
dopted for simulation analysis and listed in Section 5.5.2.
5.2.3.3 Optical
Source Modeling
A
b
lock
d
iagram
o
f
t
he
o
ptical
t
ransmitter
s
ystem
t
o
b
e
c
onsidered
i
s
i
llustrated
i
n
F
igure
5
.16.
I
nput
s
ignals
a
re
e
lectrically
e
ncoded
b
y
u
sing
l
aser
d
rive
c
ircuit.
T
he
op
tical
s
ource
i
s
a
ssumed
t
o
b
e
s
ingle-longitudinal
m
ode
s
emiconductor
l
aser
i
n
w
hich
t
he
i
njected
l
aser
c
urrent
I(t) i
s
a d
igital
p
ulse
w
aveform
I t I A I t kTbias k p
k
( ) = + −
( )
=−∞
∞
∑
(5.28)
where
A
k
is the input data sequence (A
k
= 0 or 1 for ...