J. Desforges, É. Gaudet, S. Gauvin
Groupe de recherche sur les couches minces et la photonique (GCMP), Département de physique et d’astronomie, Université de Moncton, 18, Avenue Antonine-Maillet, Moncton, N.-B., E1A 3E9, Canada
We describe an exact and new formalism in order to characterize materials of arbitrary absorptance between a substrate and a superstrate, also of arbitrary absorptance. This method consists in correcting the experimental transmittance curves so that the maxima reach a value of 100%. This formalism is particularly simple since, unlike other methods, it only uses information from a single transmittance curve and, if necessary (in the case of extremely absorbent materials or very thin layers that produce few maxima), a reflectance curve. This greatly simplifies the experimental procedure. This method is applied to simulated data (in order to eliminate experimental artefacts, such as noise) and real experimental data. In both cases, the results are excellent. Regarding the simulated data and in order to remain as rigorous as possible in the description of the refractive index, we use the exact Kettler-Helmoltz dispersion relation (Lorentz profile) instead of the approximate Sellmeier relation.