| 1. |
- Ruder, Alexander, et al.
(författare)
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Mueller matrix ellipsometer using dual continuously rotating anisotropic mirrors
- 2020
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Ingår i: Optics Letters. - : OPTICAL SOC AMER. - 0146-9592 .- 1539-4794. ; 45:13, s. 3541-3544
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate calibration and operation of a single wavelength (660 nm) Mueller matrix ellipsometer in normal transmission configuration using dual continuously rotating anisotropic mirrors. The mirrors contain highly spatially coherent nanostructure slanted columnar titanium thin films deposited onto optically thick gold layers on glass substrates. Upon rotation around the mirror normal axis, sufficient modulation of the Stokes parameters of light reflected at oblique angle of incidence is achieved. Thereby, the mirrors can be used as a polarization state generator and polarization state analyzer in a generalized ellipsometry instrument. A Fourier expansion approach is found sufficient to render and calibrate the effects of the mirror rotations onto the polarized light train within the ellipsometer. The Mueller matrix elements of a set of anisotropic samples consisting of a linear polarizer and a linear retarder are measured and compared with model data, and very good agreement is observed. (C) 2020 Optical Society of America
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| 2. |
- Stokey, Megan, et al.
(författare)
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Brillouin zone center phonon modes in ZnGa2O4
- 2020
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 117:5
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Tidskriftsartikel (refereegranskat)abstract
- Infrared-active lattice mode properties of melt-grown high-quality single bulk crystals of ZnGa2O4 are investigated by combined spectroscopic ellipsometry and density functional theory computation analysis. The normal spinel structure crystals are measured by spectroscopic ellipsometry at room temperature in the range of 100cm(-1)-1200cm(-1). The complex-valued dielectric function is determined from a wavenumber-by-wavenumber approach, which is then analyzed by the four-parameter semi-quantum model dielectric function approach augmented by impurity mode contributions. We determine four infrared-active transverse and longitudinal optical mode pairs, five localized impurity mode pairs, and the high frequency dielectric constant. All four infrared-active transverse and longitudinal optical mode pairs are in excellent agreement with results from our density functional theory computations. With the Lyddane-Sachs-Teller relationship, we determine the static dielectric constant, which agrees well with electrical capacitance measurements performed on similarly grown samples. We also provide calculated parameters for all Raman-active and for all silent modes and, thereby, provide a complete set of all symmetry predicted Brillouin zone center modes.
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