
416 Optical Fiber Communication Systems with MATLAB
®
and Simulink
®
Models
therefore,
t
he
N
F
i
s
ex
pected
t
o
b
e
m
uch
h
igher.
F
igure
1
0.11
i
llustrates
t
he
i
mpact
t
hese
c
ongurations
h
ave
o
n
t
otal
N
F.
I
t
s
hows
a
n
i
mprovement
o
f
o
ver
1
0
d
B
f
or
f
orward
p
ump-
ing
c
ongurations.
W
hen
v
arying
t
he
b
ackward
p
umping
r
atio
f
or
d
ifferent
bers
o
ver
t
he
s
pan,
t
he
d
ifferent
v
alues
o
f
N
F
w
ere
d
etermined
a
nd
s
howed
t
hat
f
or
r
educed
R
aman
g
ain
c
oefcient,
R
values, the impact of the pumping scheme, forward to backward, on
t
he
N
F
w
as
r
educed.
A
s
t
he
N
F
i
s
d
ependent
o
n
t
he
p
umping
po
wer
a
nd
t
he
n
et
g
ain,
i
f
i
t
i
s
u
sed
i
n
a
h
ybrid
s
ystem
c
onguration,
a
n
E
DFA
p