Contemporary and Future Trends in Optics - Optical Signal Processing by Silicon Photonics - page 13

Fig. 2.1 Linear and nonlinear interactions

Table 2.1 Comparison of nonlinear effects
Characteristics

Nonlinear phenomena
Self-phase
modulation

Cross-phase
modulation

Four-wave
mixing

1. Bit-Rate Dependent Dependent Dependent

2. Origin Nonlinear susceptibility Nonlinear

susceptibility

Nonlinear
susceptibility

3. Shape of broadening Symmetrical May be symmetrical -

4. Energy transfer
between medium
and optical pulse

No No No

5. Channel Spacing No effect Increases on

decreasing
the spaces

Increases on
decreasing
the spaces

nonlinear Schrodinger equation is shown when its time domain conversion is
done. The four-wave mixing process for both pulsed and continuous-wave pump-
ing is considered and discussed the circumstances under which wavelength con-
version and parametric amplification can be realized with possible gain in the
telecommunication band.
The nonlinear phenomena of cross phase modulation and SRS were discussed
emphasizing on the effect of free carriers on lasing and Raman amplification. The
main focus of their work was on the Four Wave-Mixing process and its applications.
They also took into account the impact of free carriers first and showed that, besides
the index changes induced by them caused a insignificant impact on Four Wave-
Mixing, efficiency of FWM is effected by FCA such a way that considering the CW
pumping case, a net positive gain cannot be realized in the telecommunication band.