
Third-Order Susceptibility 199
Normalized time
Intensity
–2
0.0
0
2
1.50.50.0
1.0
0.5
Figure 3.18 Pulse envelope according to Eq. (3.158) for different values of 3βz/τ
G
.
It should also be noted that SPM in connection with saturation, which
was discussed previously, is a particular example of a time-dependent sample
response. In the case of saturation, there is a memory effect associated with
the change of occupation numbers, with a characteristic time determined by the
corresponding (energy) relaxation time.
3.6.4. Counter-Propagating Pulses and Third-Order
Susceptibility
In a laser cavity, we may encounter the situation where counter-propagating
pulses meet ...