Calculation of thin-film optical constants by transmittance-spectra fitting

摘要

Our investigation uses the film-interference transmittance spectrum in the computer calculation of thin-film thickness t and complex refractive index n* = n - ik. Titanium oxide films of different thicknesses are studied, and a new approach to determine the film thickness and optical constants is proposed. This new approach is based on the use of numerical optimization methods in transmittance-spectra fitting. Various dispersion equations of the finite-power-series type are used to obtain the best fit between transmittance measurements and calculations. The best-fit results for n（λ) and k(λ) are found to agree with dispersion relations that follow from a quantum theory of light absorption. # 1998 Optical Society of America [S0740-3232(98)00107-0] OCIS codes: 070.4790, 120.4530, 120.5240.