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

149
Symbol
Ebl
Efl
Eflr
E frO
E f2
a
Description
bound wave in GaN
free wave in GaN
free wave in GaN reflected from the GaN/AI 2 0 3 interface
free wave in air reflected from air/GaN interface
free wave in sapphire transmitted
round trip phase acquired by E frl
~ phase acquired by E f2 during round trip of E fr1
Table 6.3: Nonlinear waves and phases
multiple reflection in the GaN film before transmission through the GaN / Al 2 0 3 substrate.
The fields generated at the air/GaN interface and E fr1 propagate from point
.-\ to point C in Fig. 6.4. This field is related to Ef2' which is the nonlinear free waw
initially transmitted through the GaN/Ah03 interface as IEfrtl ~ O.lIEnl. :\"'ote
that the fields generated at the air/GaN interface and E f2 propagate from point .-\
to point B in Fig. 6.4. Contributions of nonlinear waves that undergo more than one
set of reflections in the GaN film affect the total transmitted SHG intensity by less
than ",,2% and are therefore not included in our theory. The interference of E f2 and
E fr1 is computed by summing their respective contributions at points Band C.
In our analysis, we express the nonlinear fields in terms of the wavevectors and
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