A New Simple Analytical Method for a Highly Accurate Determination of the Optical Parameters of a Slab from Transmittance Data

Abstract

To date, determining with high accuracy the optical parameters (extinction coefficient k and refractive index n) of a slab from the sole transmittance data requires an inverse method based on numerical iteration procedures. In this paper, we propose a new inverse analytical method of extracting ( k, n) without numerical iterative processes. The high accuracy of this new inverse method is assessed, and as an application example, the optical parameters of CaF2 and Si substrates are determined in the IR spectral range of 4–8 µm.

Simple Design of Double-Layer Antireflection Coating for Er-Doped Glass Laser Application

“…To such a goal, a convenient spectrophotometric method consists in measuring the transmittances (T 1 and T 2 ) of two samples (of different thicknesses d 1 and d 2 ) of the same material. A simple analytical method published recently [17] allows then the derivation of the optical parameters (k S , n S ) of the substrate from the (T 1 , T 2 ) experimental data. In our case, samples have been prepared with thicknesses d 1 = 2.80 mm and d 2 = 34.98 mm, for which FTIR (Fourier-transform Infrared Spectroscopy) measurements are easy to carry out.…”

“…From the transmittance data, the extinction coefficient k S and the refractive index n S of the Er-glass substrate are easily determined, using analytical expressions [17]. The evolution of k S and n S is shown in Fig.…”