Page 305 - Fiber Optic Communications Fund

286 Fiber Optic Communications

200

150
Pump power (mW) 100

50

0
0 10 20 30 40 50
Length (km)

Figure 6.26 Decay of the Raman pump. The parameters are the same as those of Fig. 6.24.

35

30
P s (0) = –6 dBm
25
P s (0) = 0 dBm
G (dB) 20 P s (0) = 6 dBm

15

10

5
20 22 24 26 28 30
Pump power (dBm)

Figure 6.27 Dependence of gain on the pump power. Gain saturates as the signal power increases. The parameters are
the same as those of Fig. 6.24.

For the backward-pumping scheme, the evolution of signal and pump powers is given by
dP s g r
= P P − P , (6.209)
s s
p s
dz A p
dP p g
p
− =− R P P − P . (6.210)
p p
p s
dz A
s s