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

10
the electric fields as
In this thesis, we are concerned principally with second-harmonic generation
(SHG), which is mediated by the second term in equation (2.3) with w = 2w o • i.e.
(2.-1)
Since dipole allowed nonlinearities occur in GaN, the local field approximation is
valid.
Once the second-order nonlinear polarization is determined from the second-order
susceptibility and the incident fields, the nonlinear fields generated within the medium
are determined from boundary conditions and the nonlinear wave equation
€(w) 8 2 47r 8 2 2
'V x 'V x E(w} + --E(w} = ----p( }(w).
Solutions to equation (2.5) must also satisfy
c2 8t 2 c 2 8t 2 (
.) -) _ .. J
'V. D(w) = 0 (2.6)
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