Fig. 4.21 An example of the nonlinear differential equation (DE) solution of fourth order for
QWLD in the quasi-stationary mode without taking into account the lag in the optical channel
(DE (4.37)). (a) Instantaneous values of the EMF strength E n (t), y(t) ¼ E n (t) for different initial
conditions and phase portraits {y(t), y
0
(t)}(1,2,3,4); (b) Instantaneous values of the EMF strength y
(t) ¼ E n (t) for different initial conditions in one plot for normalized time. The DE (4.37) for y
(t) ¼ E n (t): y
4
ð Þ þ 0:01y
3
ð Þ þ 2:0001y
00 þ 0:01y
0 þ 1:0001y ¼ À0:5 Á
∂
2
∂t 2
y
1þ0:01y 2
178
4 Semiclassical Theory and Laser Differential Equations for Optoelectronic. . .