Generalized Dispersion Properties of Thin-Film Waveguides

The dispersion properties of a thin-film optical waveguide for TE and TM modes are expressed in simple and general analytic forms. These formulas describe the variation of the effective refractive index with respect to any physical parameter with which the refractive index of any layer or the thickness of the guiding layer may vary. Universal curves for both TE and TM modes are given, and applications of the formulas are discussed

Stress in Silicon Oxide Thin Films Grown by Dry Thermal Oxidation

Dry thermal oxidation is performed at 900, 950, 1000, and 1050 C in fused silica tube furnace (Sandvik)for 10, 20, 50, 100 and 200 min. The properties of the thin-films such as refractive index and stress arestudied in this paper. Refractive indexes of the thin-films are obtained using ellipsometer and decreasesfrom 1.78 to 1.46 as the film thickness increases.Stress of the thin-films is theoretically calculated,experimentally measured and then compared.Stress is calculated theoretically using Stoney’s stressequation and Goklaney’s stress equations. Stress is measured experimentally using the profilometer. Ex-perimentally measured stress and refractive indexes are then compared to discuss the density of the thin-films

Determination of Thickness and Optical Parameters of Thin Films from Reflectivity Spectra Using Teaching-Learning Based Optimization Algorithm

In this paper, we report a simple method to extract thickness and refractive index of thin-film from experimentally measured reflectivity spectra using teaching-learning based optimization (TLBO) algorithm. The algorithm finds thickness and refractive index by fitting an experimentally measured reflectivity spectra with theoretically ones generated by transfer matrix approach. The value of refractive index as a function of wavelength is determined by considering sellmeier dispersion relation. The algorithm is implemented by means of an interactive numerical simulation using LabVIEW as a programming tool. To check the effectiveness of the self-developed program, it is tested on different thin-film samples prepared from some commonly used optical materials such as MgF2, Al2O3 and SiO2 using electron beam evaporation technique. The values of thicknesses and refractive index spectra for different thin-film samples obtained by TLBO algorithm are verified using standard spectroscopic ellipsometry measurements. It is found that there is an excellent agreement between the results obtained by the TLBO algorithm and those by ellipsometry. It is also demonstrated that a simple reflectivity measurements give the valuable information about the thickness and dispersive refractive index over a range of wavelengths, which are obtained by our self-developed simulation program based on TLBO algorithm