William Angerer - Department of Physics and Astronomy - University ...

148
L x
i
d
1
E( 00)
air
GaN
sapphire
(pi! rplO E frl
Figure 6.4: Geometry of nonlinear waves in GaN/AI 2 0 3 . Notation is summarized in
Table 6.3.
nonzero nonlinear waves in air, GaN, and sapphire, and defines phase relationships
between the waves.
Our model includes all factors that affect the calculated second-harmonic signal
by at least 10%. Thus, the model does not include the effect of bound wave reflection
from the GaN / Al 2 0 3 interface because the reflection coefficient is small. i.e.
ITs12(w)12 :::::: 0.03 and IT p 12(W)1 2 :::::: 0.015, where Tsdw) is the Fresnel reflection coefficient
for s-polarized light with 1 (GaN) as the incident medium and 2 (sapphire)
as the substrate medium. T p 12(W) is the Fresnel reflection coefficient for p-polarized
light at the same interface. However, we include E,rl in our analysis, which is the
nonlinear wave that is reflected from the GaN / Ah03 interface and undergoes one
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