Advancements in Silicon Photonics - Optical Signal Processing by Silicon Photonics - page 40

(f) Optical rectification is basically the generation of electric fields that are
quasi-static.
(g) Four-wave mixing (FWM) can also be the result of other nonlinearities.
4.6.2 Linear Versus Nonlinear optics
Linear optics can also be referred as the optics of weak light. It is described as the
light is deflected or delayed without its frequency being unaffected.
NLO is also referred as the optics of intense light; it can be described as the
special effects that the light itself induces and it propagates through the medium.
4.6.3 Other Nonlinear Processes
(a) Cross-phase modulation (XPM)
(b) Four-wave mixing (FWM)
(c) Cross-polarized wave generation (XPW)
(d) Optical Kerr effect
(e) Intensity dependent refractive index
(f) Self-focusing
(g) Kerr-lens modelocking (KLM)
(h) Self-phase modulation (SPM)
(i) Optical solitons
(j) Raman amplification
(k) Optical phase conjugation
(l) Two-photon absorption
(m) Optical phase conjugation
(n) Brillouin scattering
4.7 Silica on Silicon
The waveguides with step index, having symmetric rectangular cross-section are
formed. A layer of SiO 2 wraps the silicon substrate and at core the doped SiO 2
layer is deposited. Photolithography is used to pattern the core and then another
layer of SiO 2 is deposited. Figure 4.7 shows the processing steps. The gray layer
as shown in figure is of silicon substrate and SiO 2 is deposited on it. On top of this
layer, doped SiO 2 shown in dark blue color is deposited, and then lithography and
etching are used to pattern this layer. As a last step the conformal deposition of