Determination of refractive index, extinction coefficient and thickness of thin films by the method of waveguide mode excitation

We propose a method for measuring simultaneously the refractive index n_f, extinction coefficient m_f and thickness H_f of thin films. The method is based on the resonant excitation of waveguide modes in the film by a TE- or a TM-polarised laser beam in the geometry of frustrated total internal reflection. The values of n_f, m_f and H_f are found by minimising the functional φ = [N^-1Σ^N_i=1(R_exp(θ_i) – R_thr(θ_i))²]^1/2, where R_exp(θ_i) and R_thr(θ_i) are the experimental and theoretical coefficients of reflection of the light beam from the interface between the measuring prism and the film at an angle of incidence θ_i. The errors in determining n_f, m_f and H_f by this method are ±2 × 10^-4, ±1 × 10^-3 and ±0.5%, respectively.