• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.592-598
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• 2017

A method for estimating the optical characteristics of ceramic materials under high temperature conditions has been applied and evaluated. For that purpose, an interface system combined with a photo-spectrometer was made to keep the samples at the required high temperature. The transmittance of the samples was measured at various temperatures. The measured transmittance data was used to estimate the refractive index using an optical simulation model in conjunction with the Sellmeier equation. The Sellmeier equation parameters were selected by trial-and-error when the transmittance recalculated using the estimated refractive index was compared with the measured transmittance. Furthermore, the estimated refractive indices were checked by a comparison with the reference data at some typical wavelengths at room temperature.

• ETRI Journal
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• v.31 no.6
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• pp.667-674
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• 2009

Terahertz time-domain spectroscopy has been used to study the optical and dielectric properties of three chalcogenide glasses: $Ge_{30}As_8Ga_2Se_{60}$, $Ge_{35}Ga_5Se_{60}$, and $Ge_{10}As_{20}S_{70}$. The absorption coefficients ${\alpha}({\nu})$, complex refractive index n(${\nu}$), and complex dielectric constants ${\varepsilon}({\nu})$ were measured in a frequency range from 0.3 THz to 1.5 THz. The measured real refractive indices were fitted using a Sellmeier equation. The results show that the Sellmeier equation fits well with the data throughout the frequency range and imply that the phonon modes of glasses vary with the glass compositions. The theory of far-infrared absorption in amorphous materials is used to analyze the results and to understand the differences in THz absorption among the sample glasses.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.1-7
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• 2003

We determined the optical constants of organic light emitting material of Alq$_3$ in a spectral range between 1.5 and 6 eV using the physical model introduced by Forouhi and Bloomer［Phys. Rev. B 34, pp. 7018-7026, 1986.］. The initial parameters of $A_i,\;B_i,\;C_i$ of Forouhi-Bloomer dispersion relations were determined from the absorption peaks and widths of absorption spectra of the Alq$_3$ film. The refractive index of substrate, a fused silica, is derived from the Sellmeier equation with the measured transmittance and reflectance spectra. Then, the complex refractive index and thickness of the Alq$_3$ film were calculated by use of a nonlinear least square fitting program with the Forouhi-Bloomer dispersion relation and the measured transmittance and reflectance spectra.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.654-659
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• 1996

Amorphous $TiO_2$ thin films were deposited on silicon substrates by the RF magnetron sputtering under various conditions, and studied by the spectroscopic ellipsometry (SE). To determine the optical constants as a function of photon energy and also to depth-profile the as-deposited $TiO_2$ thin films, we analyzed the ellipsometric spectra using the effective medium approximation and the dispersion equations. Especially, we improved the modeling accuracy by selectively using either the Sellmeier or the Forouhi and Bloomer dispersion equation in different energy regions.