
164 Optical Fiber Communication Systems with MATLAB
®
and Simulink
®
Models
where
f
r
denotes the resonant frequency given by
f a v N
I t
I
r
p n
g p
b
= +
( )
−
1
2
1
1 1
0 0
π τ τ
τΓ
( )
(5.24)
and
〈F
S
F
N
〉 denotes cross-correlation given by
F F
V N V S V S
s N
a sd a sd
N
a sd
p
= −
+
+
β
τ τ
( )1
(5.25)
and
c
onstant
Ψ d
enotes
Ψ Γ= +
1
2
1
0
π τ
a v S
g sd
n
(5.26)
The
typical
relationship
between
the
inject
current
injected
into
the
lasing
cavity
and
the
output
intensity
of
the
FP
laser
and
its
variation
with
respect
to
temperature
is
shown
in
Figure 5.13. It is noted that the threshold current varies as the temperature changes. If the
laser
chip
is
not
cooled
by
a