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

Chapter 4
Linear Optical Measurements
Investigation of the optical properties of a material naturally begins with a measurement
of its dielectric constants. The dielectric constants, €{w} = €t(u.:) + i€2(;"'':).
determine the transmission, reflection, and absorption coefficients of light from matter.
Along with the thickness of the medium, these coefficients precisely specify the
propagation of light through a medium. Since the second-harmonic fields generated
in our nonlinear materials are strongly dependent on the linear optical properties
of the media, precise knowledge of linear optical properties is required to extract
x~JL(w'
= 2wo} from our nonlinear optical spectroscopic data.
Previous measurements of Gal'J had not measured the dielectric constant near the
band gap [22. 13. 53]. In order to fully characterize the linear optical properties of
our GaN / A1 2 0 3 films, we performed a series of linear spectroscopic measurements.
which are described in the following sections.
\Ve have described the sample preparation in section 5.5. Briefly, a 0.050 J.Lm layer
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